How to Make a Smoke Bomb the Failsafe Way—We Thought!

Sometimes, learning how to make a smoke bomb using colored smoke can be tricky. Even if you already know how!

Because even if you really do already know how to make a smoke bomb, you can still have problems getting your colored smoke to work…problems you may not expect.

How to Make a Smoke Bomb the Failsafe Way—We Thought!

Skylighter has been offering organic powdered dye pre-mixed with the other necessary colored smoke chemicals for years. These premixed colored smoke components make it a lot faster and easier to make smoke grenades and make smoke bombs. We even got Ned Gorski to write an excellent and detailed project article on How to Make Smoke Bombs, complete with color photos, and even videos.

Skylighter sells that pre-mix as “colored smoke mix.” You buy a pound of the colored smoke mix, combine it with a pre-measured amount of just one other chemical, potassium chlorate, load it into a capped tube, and voila. You have a homemade smoke bomb, ready to light.

Usually.

Except, now people were having problems getting their colored smoke to light.

When this problem started to show up repeatedly, I finally decided to roll up my sleeves and look into it. What I found, though anything but earthshaking, is a good little lesson in simple pyrotechnic detective work.

And it is exactly the same kind of problem diagnosis and solution, which anyone who makes fireworks will eventually run into.

So, ride along with me a ways. It won’t take long, and there are a couple of good tips and tidbits that anyone can use.

What we try to do with our colored smoke bomb kits is make it really simple, fast, and idiot-proof to make a smoke bomb. But in trying to make it too simple, we may have overlooked the obvious.

Here was the problem: Customers were mixing the correct weights of the two-part colored smoke components (smoke mix and potassium chlorate) correctly—according to the instructions Skylighter provided. But when they tried to light the stuff it wouldn’t burn. Or it would light, and then go out.

Now when you light colored smoke it is supposed to smolder, not catch on fire.

The key is having exactly the right ratio of the potassium chlorate oxidizer to the smoke mix fuel. Screw the ratio up one way and your mix will burn too fast.

This is very important. If your mix actually burns, you won’t get the colored smoke you want. Just black, brown, or some other characteristic dark color of burning material.

Screw the ratio up the other way, and your colored smoke mix will not ignite at all.

Colored Smoke Detective Work

When we first heard about the problem with a single colored smoke color, we simply took some of our smoke mix here, mixed it properly with the potassium chlorate, and burned some outside.

Hmmm… there is some kind of problem. Perhaps the company, which formulates our colored smoke mixes, changed the brew in some way. They said not, but chemicals can be different, from batch to batch, or year to year. And unless you do time consuming and expensive testing of each batch you get, you might never know. So, we all tend to rely on good suppliers, brands, and model/spec numbers instead.

Making our smoke mixes does involve carefully weighing and blending at least 3 different chemicals.

It did visually appear that the blending/mixing was not as thorough.

But hundreds of pounds of these colored smoke mixes were already out on the street in customers’ hands. What to do?

We found that if we increased the amount of chlorate added to the smoke mix, that we could get it to burn. So that’s what we recommended to people who were having problems. We even sent out additional potassium chlorate at no charge, and replacement smoke bomb kits.

The problem reports continued nonetheless. Some people were not able to add additional chlorate and solve the problem. And then other colors started to have the same problem.

Hmmm… what else could be wrong?

A little background will help here. Because colored smoke dyes are “dirty” to work with, we recommended that folks use “bag mixing” to mix the chlorate and smoke mix.

Basically, this involves dumping the two parts into a big zip-lock, sealing it, and then mushing the contents around for a while until there’s a homogeneously colored powder inside with no lumps.

The theorem I developed was that for reasons unknown, either or both of the two-part smoke mixture had either increased in particle size and/or gotten “clumpy”—a scientific term describing what happens when a chemical gets a little bit of moisture in it.

Well, for sure the chlorate had. You could look at it and tell.

I ran some of our blue smoke through a 30-mesh kitchen strainer and found the same thing. More clumps. Maybe even larger particles.

So, here’s a lesson in pyro 101.

When we first started offering two-part colored smoke kits, it’s a fact that both the colored smoke fuel and the potassium chlorate were very fine (particle size), free flowing powders, something you almost always want in your fireworks chemicals.

And we had no reports of problems igniting the smokes.

Now, with lumpy, clumpy material, what has happened? Well think about it. It’s simple. The particle size of both parts has increased. When particle sizes are larger, surface area is decreased.

Since the pyrotechnic burn we want depends on many little particles of fuel and oxidizer being in close contact with each other AND since we know we had that balance exactly right when the two powders used to be fine powders that were free flowing, then the surface area is no longer adequate for the ratios we were using.

And that’s exactly why adding a little more potassium chlorate had solved the problem for some people. The large surface area problem meant that if we changed the ratio of oxidizer to smoke fuel, we could indeed get the smoke to light again.

But over time as BOTH fuel AND oxidizer got clumpier and clumpier, even that solution didn’t work.

Why? Because the mix was simply too coarse to take fire using the bag mix with the two chemical components we were providing.

The Tests

Experiments proved this out. Armed with the info above and my theorem that it was merely a particle size problem, I set out to solve the problem AND try to do it in a way that would involve the least hassle and expense for both Skylighter and our customers.

It took about two hours. Like most of my testing, I try to work with very small batches. This speeds up the process by reducing weighing, milling, and mixing. And reduces the cost of materials, a lot of which is often wasted doing the testing.

I was pressed for time; so I had the guys in the warehouse, first pre-measure a lot of little baggies of potassium chlorate and colored smoke mixes.

I took the box of this stuff home, realizing only later that the little white powder bags could have brought big smoke down on me, had I been stopped with them. (“No, no, no, ossifer. Those little white powder baggies aren’t what you think at all. Actually, if I mix the white stuff in with this colored stuff, and light it, you will get purple colored smoke! Wait, ossifer, I am not trying to burn the evidence. No, wait. Stop. Those things are too tight on my wrists. I wanna call my mama, ahhh lawyer!”)

First problem was finding someplace that wasn’t windy. I don’t do this stuff indoors in my shop any more, and smoke dyes are easily blown around by even stray puffs of wind.

I found a corner against a shed, out of the wind, and set up my scale, two coffee grinders, some mixing cups, a small kitchen strainer screen, and my trusty pyro notebook.

I aimed for a ratio of 14.2 grams of smoke mix to 5.2 grams of potassium chlorate. That’s the ratio we devised early on that would work with all of our smoke mixes, regardless of color. And we knew from history it used to work.

My test burn container for all experiments was a 9/16” ID x 1-1/2” long tube (called an M80 tube in some circles) with a cardboard plug in one end, the other end open.

FYI, colored smokes do not have to be confined to do their thing. I left one end of each test-tube open for the tests.

Experiment 1: I added the two chemicals together in a zip lock and sqwooshed ‘em together for ten minutes. The now infamous, bag mix method. Filled a test tube, inserted a piece of Visco and lit it. Failed to light. This mix would not even light when directly blasted with a blowtorch.

Experiment 2: I repeated the process in Experiment 1, but with an additional 10% potassium chlorate. Lit the fuse, and it too failed to ignite. Blowtorching the loose mix caused it to light, but it could not sustain the burn, and went out.

Experiment 3: Repeated #2 again adding +10% chlorate, but instead of bag mixing, screened the mix 3 times. Lit the fuse, and the smoke mix ignited, the burn was sustained, but with a “sputtering” burn, and an okay, but not rich blue smoke.

Experiment 4: Since the potassium chlorate was the lumpier of the two components, I used a coffee and spice grinder to grind the chlorate to a fine, fluffy powder, with about 20 seconds of pulse milling. Weighed the two components in the original 14.2/5.2 grams ratio. Screened the two components together 3 times. The mix burned correctly.

Experiment 5: Repeated #4, but I also blade milled the smoke mix for 20-30 seconds as well, before screen mixing together 3 times. The mix burned even better. Full rich blue smoke. The volume of smoke was the greatest of all the test burns.

Conclusion

The particle sizes of both components need to be as small as possible. If there is a problem getting the smoke mix to burn, then milling both components separately to a finer particle size, as well as using a better mixing method will likely solve the problem.

This will not solve all fireworks mix problems. But if you think particle size or clumping may be your problem, the method described above is a quick and simple test to find out.

Cost: Cost to solve the problem at Walmart–$34: 2 coffee mills, $14 each; one small wire strainer, $6. And everything is reusable later on in my fireworks shop.

More on cheap chemical milling using a coffee (blade) mill.

Tell Me What You Think: Was this Article Helpful to You or Not?

Just leave a comment below. Thanks.

- Harry

Fireworking Safety, the Law, and You

I’ve covered many safety issues involved in making fireworks in my introductory essay to Kyle Kelley’s The Pyrotechnist Survival Guide, Bill Ofca’s Fireworks Safety Manual, and Dr. Takeo Shimizu’s treatise on Preventing Accident.

Much physical suffering on our part and that of our loved ones can be avoided if we heed the advice in those pages. I like to go back and review them regularly to see how well my operations are conforming to those recommendations.

But there is another very significant kind of pain and suffering we and our families may have to endure unless we pay attention to a different set of precautions as we embark on this new fireworking hobby.

I’m going to go over what it takes to make fireworks legally, and I’ll even show you how to make a magazine inexpensively to use for legal storage of the fireworks you make.

The US Department of Justice, Bureau of Alcohol, Tobacco, Firearms and Explosives (BATFE) is charged with regulating explosives activities in the United States. Their regulations can be found in ATF Federal Explosives Law and Regulations, commonly called the Orange Book because of its orange cover.

Here is a link to a free online, PDF version of the Orange Book:

http://www.atf.gov/explarson/fedexplolaw/2007edition/index.htm

The book can be obtained from the BATFE directly, also, and from Skylighter.

Individual states either defer to Federal explosives regulations or develop their own explosives laws.

Local governments such as counties, cities, and townships can adopt their own sets of laws governing explosives and their manufacture.

You might be saying right about now, “What am I getting myself into?”

The simple answer is that you’ve gotten yourself into a serious hobby and art form, one which can cause personal injury and property damage, and one in which the government takes an interest, unlike knitting or stamp-collecting.

“Well, the heck with them. I don’t care about their stupid laws,” you might reply.

Well, guess what. The various governments don’t care whether you and I consider the laws stupid. They care about the laws and they care about whether or not we are complying with them. You’d better believe it.

We could sit around for hours or even days, debating this law or that one, which one is just or unjust. But that won’t change the fact of the existence of both the law and the agency, which enforces it.

The question is not whether the law is just or not, or whether or not I agree with the law.

The question becomes a simple one: “Am I willing to suffer the consequences if I am caught breaking the law and prosecuted? Is my family willing to suffer those consequences along with me? Am I willing to ask them if they are willing to suffer those consequences.”

There have been many pyros who have been caught breaking the laws concerning the manufacture and storage of fireworks. They have suffered imprisonment, high attorney fees, exorbitant fines, broken marriages, and loss of property.

In the end a law is simple. “We the people declare this activity, done this way, to be illegal. If you are caught doing it you will suffer these consequences.”

A law states just that and only that. It simply states, such and such an action is illegal, and if you are caught doing it you may suffer this punishment.

So, the choice then becomes simple. “Am I willing to comply with the law, or break it and risk those consequences?”

And, there are several different ways to answer that question.

1) Yep, I’ll comply with the law and not take the risks involved in breaking it.

2) Nope, I’ll not comply with the law. I’m going to engage in this activity in an illegal manner, and I’m willing to risk those consequences. But, I’m not gonna tell my wife I’m taking that risk with our money and property, or give her the choice of whether or not she’s willing to take that risk.

3) Nope, I’ll not comply with the law, and I’m willing to risk those consequences, and I have discussed it with my wife and family and they are willing to back me up in this activity and risk those consequences, too.

But, comply or not, we need to take that action with an awareness of the consequences of our actions, and a willingness to face those consequences like “men”. (Most fireworkers are men, so I’m comfortable using that term. No disrespect to wimmen fireworkers, though.)

I said in my safety essay mentioned in the first paragraph above, “When we first get into this, we really don’t know how serious a pursuit it will become for us, do we? How much should we invest in tools and a workshop if it turns out to be only a passing curiosity? If we progress in the fireworks hobby, our investment in it and in the tools and facility used for it, progresses along with it. Our safety precautions usually end up tagging along a bit behind our activities. That is dangerous.”

Now, in that paragraph simply replace the word “safety” with the word “legal”, as in “our legal precautions usually end up tagging along a bit behind our activities.”

The danger in doing that is that we do indeed risk the sorts of “dangers” mentioned above: imprisonment, high attorney fees, exorbitant fines, broken marriages, and loss of property. As we make choices concerning our activities and whether or not they comply with those laws, it would be wise to become educated about the laws, the consequences of breaking them, and our responsibilities to ourselves and our loved ones.

Fortunately, US Federal law is pretty straightforward and simple when it comes to hobbyist fireworking.

Once again, from the ATF Orange Book:

Page 64, Paragraph 37. “When is a manufacturer’s license required?”

“Persons who manufacture explosives for their personal, non-business use are not required to have a manufacturer’s license. However, no person may ship, transport, cause to be transported, or receive explosive materials unless such person holds a license or permit.”

Page 68, Paragraph 72. “Who must comply with the storage requirements?”

“…all persons who store explosive materials must store them in conformity with the provisions of Subpart K of the regulations…”

Pages 47-53, Subpart K – Storage

This section details storage which is in conformity with the regulations and which will satisfy the BATFE’s requirements.

Because no license is required by the BATFE, this storage might never be known about by them or inspected by them. But if a person is caught storing explosives without such compliant storage, the BATFE then has the right to prosecute that person. And, typically, they do.

These are the cases you hear about in the news if the Feds are prosecuting somebody: they were storing explosives illegally, or they caught the person transporting explosives without a license or permit.

This is another important point. While a person can make explosives for their own personal use, provided that they store them in a compliant manner, they may not transport them legally unless they have an ATF license or permit. And, that’s even across town to the test-shooting site. When traveling to PGI (Pyrotechnics Guild International) or local-club events, often transportation-coverage for members is supplied through the club license and/or permit.

But, man, if you decide to transport your homemade fireworks without a license or permit, and you get stopped and searched for whatever reason, or if you have an accident and the explosives are involved in some destruction, God Help You, because the law won’t.

By the way, the US DOT (Department of Transportation) only regulates “in-commerce” transportation, and does not concern itself with the above mentioned regulations concerning the BATFE’s requirements to only transport explosives under a license or permit. At least, that’s the philosophy they appear to have been operating under so far.

Note: It’s useful to mention that all of this is my best understanding of the current situation under the law. Things can change, and the laws are always up for re-evaluation. I am not a lawyer, just a hobbyist trying to be as informed as possible about the multitude of laws surrounding us, and the numerous “alphabet soup” agencies charged with enforcing those laws. If in doubt, consult an attorney. But remember that unless they are fireworks or explosives specialists, often they can only offer their “best opinion” for you. Quite often the law is simply not all that clear, and is left to the individual “authority on site” to render a personal interpretation of it.

It is impossible for me to even try to address the myriad of local and state laws governing the manufacture of fireworks. Suffice it to say that the same sort of reasoning and responsibilities mentioned above with regard to federal laws, also pertain to state and local laws.

If you don’t research those laws and make informed choices regarding them, you might run afoul of a state or local Fire Marshal who simply does not have a sense of humor about all of this “hobbyist fireworking.”

So, if the Feds do not require us to obtain a license to make explosives for our personal use, as long as the restrictions on storage and transportation mentioned above are complied with, “Why Get One?”

Well, that’s an interesting subject.

We’ve mentioned the BATFE, DOT, State and Local agencies, and now another of those “acronym named” agencies comes into play. The CPSC.

The Consumer Products Safety Commission seems hell-bent on putting hobbyist fireworking and pyrotechnics supply houses out of business. Despite the BATFE’s declaration that no license is required for such activities, the CPSC has repeatedly forced pyro chemical suppliers to not sell more than very limited quantities of certain chemicals and supplies to unlicensed individuals.

On top of that, even though there is a perfectly valid and available “Type 50 – Manufacturer of Fireworks” license available from the BATFE, the CPSC has told the pyro supply houses that only a “Type 20 – Manufacturer of High Explosives” license is acceptable for purchases of certain items.

Go figure. I personally don’t mind trying to get informed about the law and trying to abide by it, but man, sometimes “they” sure don’t make it easy.

So, many pyro-enthusiasts are biting-the-bullet and getting their BATFE Type 20 licenses. A background check is required, and the resulting “Letter of Clearance” must be obtained. Compliant storage, as mentioned above and described in the following section, and a simple approved work-site, such as a picnic table, are necessary.

A form must be filled out and a relatively small fee must be paid. There’s an interview, fingerprinting, and a security check. And that’s about it. You don’t have to “qualify,” be tested, nor have any particular skills or background. The BATFE is not our enemy, and if we are willing to work with them, they definitely don’t view us as their enemy.

The license covers us for materials purchases, for transportation issues, and for general peace-of-mind. I personally consider it to be a good investment, if local and state laws will allow a license to be obtained.

As mentioned already, Subpart K – Storage, in the Orange book details the BATFE’s requirements for storage, regardless of whether we have a license.

Requirements for regular inspection, by the owner, of magazines to ensure that they have not been tampered with, are detailed. Housekeeping, smoking, repair, lighting, and various other issues are also addressed in this section.

Note: Interestingly, the requirements for keeping “Records and Reports” which are detailed on page 37, pertain only to “licensees and permittees.” The questions and answers regarding the requirements for “Recordkeeping,” back on page 67-68, address only licensees and permittees, as well. So while there may not be specific requirements for recordkeeping concerning the stored explosives for a non-licensed hobbyist, it’s probably a good idea to keep a log of the weights of the explosives taken in or out, or at least put in, so that the maximum weight of 50 pounds is never exceeded. A regular inventory of such explosives and their weights could also easily answer any potential questions concerning the weights and types of explosives stored in the magazine.

In general, most hobbyists install some form of a Type 4 storage magazine to comply with these requirements. A Type 4 magazine is a permanent magazine in which “low explosives” (as defined on Page 48) may be stored.

Among common fireworks components and devices, the only things, which cannot be stored legally in a Type 4 magazine, are loose “flash powders” and “bulk salutes.” Bulk salutes are flash devices stored all in one container or box together. If salutes are going to be stored in a Type 4 magazine, they must be mixed in a box with some color shells or similar. Loose flash powder may not be stored in a Type 4, period.

Other than that, a Type 4 is the storage most of us need, even if we are getting a Type 20 license (Manufacturer of High Explosives). In order to comply with CPSC’s requirements, if we explain to ATF why we want that license, and declare that we will not store loose flash powder or bulk-salutes in our Type 4 magazine), then typically the inspectors will tell us that we’re good-to-go with a Type 4.

Just remember, any explosives we manufacture and store must be stored in such a compliant magazine, whether or not we get a license.

Page 51 of the Orange book details the various requirements for the construction of Outdoor and Indoor Type 4 magazines.

Much less expensive than magazines made for just that purpose, metal shipping containers are commonly used to make outdoor Type 4 magazines They can be relatively inexpensively modified to meet the BATFE’s requirements. Page 54 has a table of distances to determine how far an outdoor magazine must be situated from inhabited buildings, highways, railways, and other magazines.

Remember the ATF places limits on the total, maximum weight of explosive material that may be stored in each type of magazine. If one wishes to install/construct an outdoor Type 4 magazine in their area, it’s useful to consult with others in your area who have done so, and with the BATFE to see what their specific recommendations and requirements are.

Many hobbyists install “Indoor” Type 4 magazines to have BATFE compliant storage for their activities. The requirements for these magazines are spelled out on Page 51.

Indoor Type 4 magazines may store a maximum of 50 pounds of actual explosive materials (does not include the weight of the containers, etc.) The magazine must be “fire-resistant and theft resistant.” “No indoor magazine is to be located in a residence or dwelling.”

An indoor magazine must be in a separate structure—not in a residence or dwelling. It appears that there is no minimum distance it must be separated from the residence of the hobbyist. The separate structure may be a garage or shed near a residence, but it may not be attached to it.

“Indoor magazines are to be constructed of masonry, metal-covered wood, fabricated metal, or a combination of these materials. The walls and floors are to be constructed of, or covered with, a non-sparking material. The doors must be metal or solid wood covered with metal.”

Covering any exposed metal to make it non-sparking can be as simple as painting it with a high-quality paint/coating such as epoxy-appliance-paint or rubberized truck-bed-lining/coating.

“Hinges and hasps are to be attached to doors by welding, riveting, or bolting (nuts on inside of door). Hinges and hasps must be installed so that they cannot be removed when the doors are closed and locked.”

“Locks. Each door is to be equipped with (i) two mortise locks; (ii) two padlocks fastened in separate hasps and staples; (iii) a combination of a mortise lock and padlock: (iv) a mortise lock that requires two keys to open; or (v) a three-point lock.”

From Wikipedia: A mortise lock is one that requires a pocket–the mortise–to be cut into the door or piece of furniture into which the lock is to be fitted. In most parts of the world, mortise locks are generally found on older buildings constructed before the advent of bored cylindrical locks, but they have recently become more common in commercial and up market residential construction in the United States.

“Padlocks must have at least five tumblers and a case-hardened shackle of at least 3/8-inch diameter. Padlocks must be protected with not less than 1/4-inch steel hoods constructed so as to prevent sawing or lever action on the locks, hasps, and staples.”

“Indoor magazines located in secure rooms that are locked as provided in this subparagraph may have each door locked with one steel padlock (which need not be protected by a steel hood) having at least five fumblers and a case-hardened shackle of at lease 3/8-inch diameter, if the door hinges and lock hasps are securely fastened to the magazine.”

So, if I have my indoor magazine in a shed, garage, or other building, which has a door, which locks with two mortise locks, the requirements for the lock on my magazine get drastically simplified.

“What the Hell??!!” I can just hear you saying right about now.

“How can I ever comply with all of this, only half of which I sorta understand?”

Well, it turns out it can be pretty simple, really.

An extremely simple indoor Type 4 magazine, which will satisfy these requirements, is a good-quality gun-safe, available at gun shops and sporting-goods stores. Make sure the locks meet the above requirements, and that the building is separated from your residence. Use epoxy appliance spray paint to cover any exposed metal on the inside of the magazine. Install some nice shelving in it. Drill some holes in the bottom and/or back of it to bolt it to the wall and/or floor to make it “theft-resistant.” And, there you have it, presto-chango, BATFE-compliant, Type 4, indoor storage.

Another option, which will come up if you search online for “lockable powder storage container,” is BATFE-compliant black powder storage boxes from sporting-goods outlets such as Cabela’s.

Here’s how you can convert a Ridgid Jobsite Storage Box, from Home Depot, into a legal Type 4 Indoor Storage magazine.

This is just one approach to creating an Indoor Type 4 magazine, compliant with the BATFE’s requirement that “all persons who store explosive materials must store them in conformity with the provisions of Subpart K of the regulations” contained in the Orange Book. (Page 68, Question 72)

Note: Please keep in mind that what follows is my interpretation of the specifications and regulations in the orange book, combined with the advice I have gotten from others. I’m no lawyer or ATF inspector. These regulations are always up to personal interpretation by the individual ATF inspectors in your area. If you have any questions about the below-listed points, it is best to clarify them with your local ATF office.

Let’s review the BATFE’s specifications for “compliant” storage.

Type 4, Indoor magazine:

• Is for storing “Low Explosives.” (no loose flash powder, no bulk salutes, no dynamite) (555.202 (b))
• May not be located in a residence or dwelling. (555.210 (b) Indoor (1))
• May only be used to store up to 50 pounds of explosives. (ditto)
• Need not be any “minimum distance” from residences or road. (555.206 only pertains to “Outdoor Magazines”
• Is to be fire-resistant and theft resistant. Need not be weather-resistant if the building in which it is stored provides protection from the weather. (555.210 (b) Indoor (1))
• Must be constructed of masonry, metal-covered wood, fabricated metal, or a combination of these materials. The walls and floor are to be constructed of, or covered with, a non-sparking material. The door/s must be metal or solid wood covered with metal. (555.210 (b) Indoor (2))
• Hinges and hasps are to be attached to doors by welding, riveting, or bolting (nuts on inside of door). Hinges and hasps must be installed so that they cannot be removed when the doors are closed and locked. (555.210 (b) Indoor (3))
• Each door is to be equipped with (i) two mortise locks; (ii) two padlocks fastened in separate hasps and staples; (iii) a combination of a mortise lock and padlock; (iv) a mortise lock that requires two keys to open; or (v) a three-point lock. (555.210 (b) Indoor (4))
• Padlocks must have at least five tumblers and casehardened shackle of at least 3/8-inch diameter. Padlocks must be protected with not less than 1/4-inch steel hoods constructed so as to prevent sawing or lever action on the locks, hasps, and staples. (ditto)
• Indoor magazines located in secure rooms that are locked as provided in the above specifications may have each door locked with one steel padlock (which need not be protected by a steel hood) (same lock specs as above) if the door hinges and lock hasp are securely fastened to the magazine. (ditto)
• There is to be no smoking, matches, open flames, or spark-producing devices within any room containing an indoor magazine. (555.212)
• The workspace used to manufacture fireworks must be at least 200 feet away from the magazine. Many hobbyist fireworkers maintain a pyro-shed, or a “work area” as simple as a portable table and tent-shelter, separated from the residence and storage magazine by a minimum of 200 feet.

I have a nice shed on my property. It is weatherproof. It is separated from my residence. I can create a “back room” in it, in which there are no spark-producing devices such as light switches, machines, or electrical outlets.

I can install two locks (a keyed entry lock and a deadbolt lock) on each of the doors leading back to the back room: the main entry door and the door to that room.

I can use the “front room” of the shed as a non-pyro workshop, as long as I keep the back room and magazine closed and secured during such operations.

So, given all of the above BATFE requirements and specifications, what sort of Type 4 indoor magazine could I put in the back room of my shed?

My pyro-buddy, Gary Smith recently sent me a picture of such a magazine design that he’s been working on. It got my “wheels turning.”

This is simply a Ridgid Jobsite Storage Box, typically used on construction sites for overnight storage of valuable tools and materials. I bought one of these boxes at my local Home Depot.

This box is constructed per the BATFE’s specifications, is coated completely with heavy orange paint, making it non-sparking, and is fire-resistant and theft-resistant, especially when it is bolted to the floor or wall.

It has two recessed areas for the kind of theft/tamper-resistant locking the BATFE specifies.

For the locks, Home Depot sells Master Lock Magnum locks, Model M5XT. They have 3/8″ thick shackles, measured across the “points” of the octagonal cross-section. The shackles are “boron-carbide,” and the locks are specified as having stainless-steel rust protection. The package indicates “Meets Maximum ASTM Industry Strength Standards,” and one package comes with two locks, which open with the same key.

The locks are specified on the package as having 1-inch of clearance between the shackle and the body of the lock when the locks are locked. The Ridgid job box instructions specify a Master No 5 lock, which has between 7/8 and 1 inch of such clearance.

So, it looks like these locks meet both the BATFE and Ridgid specifications. I’ll keep the lock-package inside the magazine in case a BATFE field inspector ever wants to go over the lock specifications to verify that they do indeed meet his/her interpretation of the agency’s requirements.

The locks are installed in the job box and held in place with u-bolts and nuts, which come with the box. When the door is closed, and the locks are locked, the body of the locks close around L-shaped bars, which project from the door. When the lock is unlocked, the lock-body slides out further in its little compartment and creates enough space for the L-Bar to slide into. (Trust me, it works just fine.)

When the door is closed and locked, the method of protecting the locks from tampering is as specified by the BATFE, including that the box is to be contained in a securely locked building.

Note: I whacked my projecting bars with a mini-sledge hammer to adjust them, so that the maximum length of the L part of the bars is engaged by the locks when they are locked.

I used a hand-held grinder, crowbar, sledgehammer, and wood block to remove the feet from the “bottom” of the box, which is now to be the “back” of the unit when it is installed as a magazine. Grinding the welds to cut them, and prying/pounding on them eventually got them off of the box.

Note: I have heard of serious incidents and accidents where someone using a grinding wheel or other grinder to sharpen tools or grind something else, has set off pyrotechnic compounds or fireworks which were stored nearby. Simply put, Do Not Grind Any Metal Near Pyrotechnics or Fireworks. Please!

I then figured out which way I wanted the door to open in the new box configuration. That then determined which end of the box would be the new “bottom” of it.

I used construction adhesive to reattach the feet to the new bottom, and to glue the swinging handle to the box, so that it would stay out of the way during installation. Placing the feet on the new bottom of the box, will keep the box up far enough off the floor to allow the door to swing freely without hitting the floor while opening and closing.

I allowed the glue to set up and dry completely before going on to the next steps.

I wanted some nice, wood shelves in the magazine, strong enough and far enough apart to support 5-gallon buckets of composition if needed.

I used some 3/4-inch-thick plywood, and some 1-inch X 1.5-inch wood scraps to create this shelving. All the wood is simply held in place with good-quality construction adhesive.

I ran a good bead of glue under the back edge of the shelves where they meet the back of the box to support them and prevent them from bowing under weight. Finally, I installed some wire-mesh “spice racks,” from the shelving department of Home Depot, on the inside of the door to provide some convenient storage for small items like one-pound cans of Goex black powder. These racks were installed so they fit between the wood shelves when the door is closed. The bolt-ends and nuts on the inside of the units were covered with clear caulking to make them non-sparking.

To install the magazine in the back room of the shed, I drilled four 1/2-inch holes in the back of the magazine, and used 1/2-inch lag-bolts and washers to secure the box to the plywood wall.

The heads of the bolts and washers were also covered with clear caulk to ensure they are non-sparking.

So, there you have it, one simple option for a legal magazine complying with the BATFE’s requirement for safe storage of explosives.

If an individual inspector ever disagrees with any of these design criteria, I’d be willing to explain the reasoning behind my “understandings,” and I’d be willing to be further educated on BATFE’s requirements and adjust my operation and magazine accordingly.

Happy fireworking, And stay safe and legal,

Ned

ngorski@skylighter.com

Gary Smith’s Secret to Making Roman Candles

What’s All the Mystery about Making Roman Candle Fireworks?

I really like Roman candles. But even though Roman candles appear to be the simplest of fireworks devices, they are a real challenge to make so that they perform consistently. Especially if you use the traditional methods you’ll find in all the books.

I’m going to show you a secret method for making Roman candles that you haven’t seen before. I promise you absolutely will not find Roman candles made like these in any of the books (at least, not yet!). Best of all, you can use this new method to overcome all the Roman candle problems that traditional candle-making methods create.

Look. Where rubber hits the road is how well your fire works in a fireworks display, right? Well, read on and learn how Roman candles work, what goes wrong, and how to make Roman candles like nobody you know has ever seen.

Here’s a video of one of the first successful Roman candles I made using the method I’m about to teach you.

Notice now consistent the timing is between the shots. One star is coming down and going out, quickly followed by the next shot. That kind of consistency and effect is what I was going for. And that’s what is hardest to achieve using traditional Roman candle fireworks-making techniques.

With all the candles I’ve made using this new method, the timing between shots has been within one second of each other. If you talk with pyrotechnics folks who have made their own Roman candles, they’ll tell you how remarkable that is.

You see, anyone can learn how to make a Roman candle, but making them so that the timing and height of the shots is consistent, well that’s what you don’t see very often.
Of course, Roman candle fireworks are a great way to test the color, burn time, effect and ignitability of your new star compositions. And a single candle is just fun to light, sit back, and enjoy. You can gang multiple candles together, say 7 of them in a bundle, or set them up in a fanned rack to fill the sky from left to right with Roman candles’ shots.

So Why is a Roman Candle Firework Called Roman?

Despite the fact that we Gorskis prefer to call these devices “Polish Candles,” for some reason that name has not caught on yet. So, why were these devices called “Roman candles” to begin with?

It seems that as far back as the early 1800’s, both French and Italian authors were using the term “Roman candles” to describe such devices. Since Italy was one of the countries which greatly influenced the development of fireworks, it is not very surprising that one of its most prominent fireworks devices would have its name associated with its greatest city, and the name of its once-sprawling empire.

Exactly What Is a Roman Candle?

Traditionally, a Roman candle has been thought of as a single-tube fireworks device which fires multiple, consecutive shots of projectiles skyward, and which emits a fountain-like spray of sparks between shots.

Those projectiles can be individual firework stars, comets with various colors and effects, single crossette comets, mine-shots of multiple stars, combination star-and-report devices, or small aerial star shells.

But one comet fired skyward from a mortar is sometimes considered to be a single-shot Roman candle. And indeed, single-shot candles, arranged in fan-shaped mortar racks, have become common in many modern displays.

Consumer-firework Roman candles can be as small as 1/2-inch inside-diameter tubes, and large professional-display candles can be found with a tube ID as large as 3 inches.

I’d suppose if you asked someone, “What are the most common types of fireworks you can think of,” the response would be something like, “Firecrackers, sparklers, bottle-rockets, and Roman candles.”

Certainly Roman candles play a part in many of our childhood fireworks memories. Often they were held in our hands as they fired, but there have been so many mishaps resulting from malfunctioning candles that hand-held Roman candles are now discouraged.

I once made the mistake of thinking I could hold a one-inch display candle in my hand as it fired. The first shot propelled a star skyward, and the rest of the candle backward out of my hand to who-knew-where. I had to quickly find it and stabilize it with my foot as it finished firing. I still haven’t lived that down in my local fireworks guild. I don’t recommend you try any similar stunts.

With these larger Roman candles, it’s best to tape them to a stake and firmly secure them to the ground before ignition.

How Is a Roman Candle Constructed?

The most common, and traditional method of Roman-candle construction involves alternating layers of black-powder lift charge, cylindrical stars, and a slow-burning candle/delay composition, with the bottom of the tube plugged with a clay bulkhead.

If you imagine lighting the candle’s fuse, it will burn down until it ignites the first increment of the delay composition. That rammed increment burns slowly like a gerb (fountain), spraying sparks out of the end of the tube, which would normally be pointing skyward. Of course, when I say “normally be pointing skyward,” this “dog and Roman candle” video from YouTube pops into my mind: http://www.youtube.com/watch?v=i8mDAae7LEY. That one shot just about takes out the kid and the old man at the same time!

When the last part of that first increment of delay composition burns through to the first star, the prime on the star burns quickly and ignites its whole surface. That, in turn, lights the first layer of black-powder lift charge, which propels the star out of the tube. At the same time, the top of the second increment of candle composition is ignited, which begins a repeat of the whole process.

The Roman candle in the sketch is called a “four-ball” Roman candle, since it will sequentially shoot four stars out of the tube. “Ball” refers to the ascending ball of flame each star will produce.

Typically candles are made with pumped, cylindrical stars, which have flat bottoms and tops. The flat bottom holds the black-powder lift charge in place, and the flat top supports the delay composition nicely.

Why Do I Make Roman Candles?

In the past 20 years or so in this hobby, I’ve only tried to make Roman candles a few times, although they are among the most elementary of devices. Quite honestly, in those attempts I was never completely satisfied with the results.

And you know what’s funny? Even though I’d made 16-inch aerial fireworks shells and 36-inch diameter girandolas, I felt like I couldn’t make a consistently performing Roman candle that would live up to my expectations.

One reason I wanted to get good at producing nice little Roman candles is that they can be fired in any location suitable for the discharge of consumer fireworks. Big fireworks devices like big shells and girandolas require a big display site and a display permit. But it’s nice now and then to make a little rocket or Roman candle and be able to take it outside to shoot and see how it performs.

In his 1947 book “Pyrotechnics,” George Weingart has a section on rolling cases (tubes), for Roman candles. He also has instructions for making an individual, 3/8-inch ID, eight-ball Roman candle.

Weingart describes a simple machine for mass-producing consumer-fireworks candles. I have seen the remains of a similar machine at the Rozzi’s Famous Fireworks plant near Cincinnati, Ohio. My understanding is that the machine I saw was the very one Weingart based his sketches and descriptions on.

How to Make a Roman Candle

I’ve seen traditional Roman-candle-making instructions elsewhere, and they seldom differ significantly from the ones in Weingart.

A parallel tube is plugged at the bottom with a rammed increment of clay or with a glued-in section of wooden dowel. A scoop of black-powder lift charge is loosely put into the tube, followed by a star, which fits nicely into the tube. This is capped off with an increment of the candle-composition delay powder, which is rammed “with about six light blows of a small mallet” according to Weingart.

And this is where Roman-candle construction gets tricky. That increment of delay composition must be rammed solidly enough to get it really consolidated and locked into the tube. That is necessary in order to prevent fire from being prematurely blown down the tube past it when the star above that increment is shot out of the tube.

The delay charge must also be in the tube tightly enough that fire cannot creep between it and the inner tube wall as it burns, which would also prematurely ignite the star below it.

If you’ve ever rammed fountain composition in a paper tube, you know it takes a fair amount of force to solidly compact the powder, in order to produce the right effect when the fountain is lit.

But, when one is ramming Roman-candle delay composition, that increment sits on top of a loose star sitting on loosely granulated black-powder lift charge. This is an inherent conflict: not an ideal situation for getting a solidly compacted increment of delay composition.

And here’s what you see as a result–the most commonly seen Roman-candle failures–stars which fire from the tube in a rapid-fire, unevenly-paced manner; sometimes more than one star fires at once; or the paper tube ruptures because of the amount of pyrotechnic material, which ignites everything at once prematurely.

All of this results from not having a solid base on which to ram each increment of candle composition. That makes the construction of these simple devices a real challenge, especially in candles larger than about a half-inch ID. Larger diameter delay increments are harder to solidly compact sufficiently than smaller diameter ones.

There must be a better way.

Enter my pyro buddy, Gary Smith. Recently on Passfire.com Gary posted a video of a fairly complex Roman candle he’d made. The individual shots were color-to-report inserts, which are harder to make than simple stars.

But, what I noticed immediately was that his shots were very evenly spaced apart, and that there was a nice fountain of fire-dust spewing from the mouth of the tube between shots.

This was a very nicely constructed, consistently-performing Roman candle, that I knew from personal experience was hard to achieve. I simply had to know more.
Gary was kind enough to share with you and me the unique method he developed of achieving nicely compacted, traditional delay increments between the shots. And that is what produced the consistent effects, which so impressed me when I first saw his video.

Using Multiple Tubes to Make One Roman Candle

Huh? Say what?

I thought we’d already defined a Roman candle as a “single-tube fireworks device which fires multiple, consecutive shots of projectiles skyward.”

How can we use more than one tube to make a Roman candle?

Well, therein lies Gary’s trick, which hopefully will forever be known as the “Smith Method” of constructing candles.

Looking at the sketch of the Roman candle above once again, you’ll notice there is a recessed, empty space below the clay bulkhead in the paper tube. Putting the tube on a base, which has a ramming nipple, and then dropping loose clay into the tube and ramming it with a drift and mallet creates that void.

Way back in Skylighter Newsletter #89, I gave directions for mixing clay nozzle and bulkhead mixes. I also showed how to ram nozzles and bulkheads, and a photograph of a cutaway tube with a nozzle rammed in it.

Either of those clay mixes is usable for the clay plug at the bottom of a Roman candle. And the photo shows how a clay nozzle or bulkhead locks into a paper tube by slightly expanding the tube in that area.

I can just imagine Gary thinking, “How can I get each delay increment solidly locked into the paper tube the same way the clay plug is?”

And then the light went on in his head: “Cut the tube into sections, ram each delay increment solidly into its section, and then reassemble the tube sections into one solid case.”

I imagine a picture popping into his mind something like the sketch below.

Although the sketch shows a 4-ball candle, additional 2-inch middle sections can be added or removed to increase or decrease the number of shots.

Note: The top, 3-inch or longer tube section creates the first “mortar” out of which the first star is shot. Within certain limits, the length of a mortar determines how high the projectile goes. Technically, 3 inches is the shortest practical tube from which to shoot the first star. But with a tube that short, the first shot will not go as high as the shots that follow it. So, I actually prefer to use a top tube section that’s 5-inches long.

I have arrived at the specific dimensions for this particular Roman candle based on my particular stars and delay composition. To the left of each increment of the delay (candle) comp there is a 1/2-inch void just like the one to the left of the clay plug.

The nipple on the ramming base creates this 1/2-inch recess in each section. A tube section is slipped onto the ramming base. The proper amount of delay composition is loaded into the tube and then rammed with a drift and mallet.

This creates a very solid, securely positioned increment of delay composition, which prevents most types of Roman candle failures.

There it is, simple as that: the Smith secret to Roman candle construction.

Now, here’s how to make a Roman candle using this method to show all the steps involved.

Now, How to Make a Roman Candle

For this Roman candle, I’m going to alternate shots of D1 glitter stars with shots of Willow Diadem silver-streamer stars. First a glitter shot, then a silver streamer, then glitter, silver streamer, etc. The candle in the video at the beginning had only silver-streamer stars.

For the willow diadem stars, I’m still using the total amount of metal that is specified in the formula. But rather than using three different types of metal, I’m only using fine, spherical titanium, Skylighter #CH3010. This long-burning star leaves a nice, long silver tail behind it that “pops” as the bits of titanium catch fire and burn.

The dimensions in the sketch above are based on my primed 5/8-inch diameter, 5/8-inch long pumped stars, which I made the same way I made the gold-glitter comets in Fireworks Tips #111.

I prime the ends and sides of the stars so that fire is transferred as quickly as possible from the top to the bottom of the star. The final primed stars end up being a little under 3/4-inch diameter and about 3/4-inch long.

The star dimensions dictate that I use 3/4-inch ID parallel tubes for this project. Either the extra-strong, 1/8-inch wall Skylighter TU1066 tubes, or the standard, 1/4-inch wall Skylighter TU1065 tubes will work well in this project.

These long tubes work well because they can be marked, and all the Roman candle sections can be cut out of one length of tube. This makes it easy to reassemble the sections later on.

I want to make an 8-shot candle, so I mark and cut a tube as shown below. I write a number on each section, starting with #1 at the bottom of the tube.

The markings will enable me to reassemble the tube sections exactly as they came apart, which will increase the potential for me to arrive at a nice straight finished candle. I allow about 1/16-inch for each of the saw cuts.

In the drawing above, notice that there will be a star at each of the cuts. So I mark 8 cuts, plus the cut at the top of the candle. The bottom section will be 1.5-inches long and the top one will be 3-inches long.

Then I cut the tube into sections.

I use a little sandpaper to smooth the inside and outside edges of each end of the tube sections. Smooth ends make for smooth reassembly later on.

Now I put section #1 on the nipple of the ramming block with the bottom of the tube down.

I made the ramming base and nipple by drilling halfway through a piece of 3/4-inch thick plywood, and epoxying a length of 3/4-inch diameter aluminum rod into the hole. I got the rod from Home Depot (in the nuts-and-bolts aisle where they have a rack of metal rods and angles), and cut it with a hack saw just long enough that 1/2-inch of it projects from the plywood. I used a file to smooth the top end and edges.

I load 10 grams (one flat 1/2-tablespoon) of bulkhead-clay mix through a funnel into the tube. When loading the clay into the short tube through the funnel, I use a 1/2-inch wooden dowel to push the clay through the funnel and slightly compact it into the tube. This helps get all the clay through the funnel and down into the short tube, so it doesn’t spill out over the top.

I ram the clay plug with a 3/4-inch rammer from one of my sets of rocket tooling, and 8 moderate blows with the rawhide mallet. This results in a 1/2-inch thick plug in the tube section. A section of 3/4-inch wooden dowel could certainly be used as a rammer in this project, as shown in the article on making gerbs.

Note: I want to fully consolidate the clay and lock it into the tube without damaging or splitting the tube. This takes a bit of practice. With the softer, standard tubes, a slight bulge will form in the tube, which can be felt if one runs their fingers up and down the tube.

Now it’s time to ram the delay-composition increments into the other sections of the tube. I have played with a variety of delay compositions, from relatively fast-burning ones to those that are slower burning. I like to keep the delay increments about 1-inch long between the stars. This provides a nice, solid plug, which does not allow fire to pass prematurely around it.

So, the burning speed of those 1-inch increments determines how much time there is between shots of the Roman candle. With the stars I am using, I prefer the timing I get using the following candle delay composition (This is a classic star formula which can be found in various books).

Chrysanthemum 8 (from Shimizu) Delay Composition

Chemical	%	79-gram batch
Potassium nitrate	0.49	35 grams
Charcoal (airfloat)	0.40	29 grams
Sulfur	0.06	4 grams
Dextrin	0.05	4 grams
Water	+0.10	7 grams
Total	1.10	79 grams

Note: The weights have been rounded off, and this size batch will make enough composition for the 8-shot Roman candle I’m making.

I grind the potassium nitrate in a blade-type coffee mill fine enough to pass a 100-mesh screen. I do the same with the sulfur. The charcoal and dextrin are already that fine.

25-50% of the airfloat charcoal can be replaced with 80-mesh or even coarser charcoal for longer hanging sparks in the fountain plume between candle shots.

The chemicals are put in a sealed plastic tub and shaken to mix them. Then they are worked through a 20-mesh screen or kitchen colander 3 times to thoroughly mix them and break up any remaining clumps of chemical.

Using a spray bottle, I spritz the composition with water as it sits in a plastic tub on a scale, until 7 grams of water has been added. Between every couple of spritzes, I swirl the comp in the tub to spread the water around.

I work the water into the powder with gloved hands and then push the damp composition through the 20-mesh colander twice to really integrate the water.

Then, just as I did with the increment of the clay in tube section #1, I ram increments of the still-damp delay composition into the remaining tube sections. I always place each section with its bottom down on the ramming nipple. This creates that 1/2-inch void in the bottom of each section as shown in the sketch.

Sections #2 through #8 now get 10 grams of the composition rammed into them. Ramming that amount of comp yields delay increments that are 1-inch long in each section. Finally, I ram 5 grams of the composition in tube section #9, which produces a 1/2-inch long delay increment.

Then I allow the delay increments to dry overnight, using my drying box. They would dry in a few days if they were put in a warm location of the storage area.

Note: Often, directions for making candles specify ramming dry, granulated delay composition. At first I wondered if I should granulate and dry the comp, and I discussed this with Gary. His theory is that damp composition slightly wets the adhesive layer inside a paper tube, and when it dries it really glues the delay increment in place. Makes sense to me, and ramming it damp really creates a dense, hard plug of composition.

Once the tube sections and delay increments are dry, it’s time to assemble the sections of the Roman candle, with lift charges and stars installed as I go along.

One homemade jig really helps at this stage, and ensures the assembled Roman candle ends up perfectly straight. I took this tip from one of the photos of Gary’s process, and expanded upon it for my own purposes.

The jig is made up of two, 36-inch long pieces of 1-inch by 1-inch aluminum angle channel from the same section of Home Depot mentioned above. One of the pieces has two 1/4-inch diameter, 2-inch long carriage bolts and nuts installed in each end to act as feet to stabilize the channel during use.

I lay out the now-dry candle tube sections in numerical order on the jig. I also lay out my stars in the order in which I want them fired, along with a cup of FFg sporting-grade black powder from a gun shop.

Of course, with a bit of dialing in, I could also use my homemade black powde for the lift.

I’ll be using Elmer’s glue to assemble the candle and a 1/4-teaspoon kitchen scoop to measure the black powder lift charges.

I have cut out little disks of tissue paper the same diameter as the tube OD to go between the stars and the lift powder. The tissue prevents the black powder from migrating up past the star between the star and the inner wall of the tube. I want to keep all the lift powder down below the star to maximize the star’s propulsion out of the tube.

To assemble section #1, I stand it, bottom down, on my workbench, and drop 1/4-teaspoonful of the black powder into the top of that section through a little funnel. I place a tissue paper disk over the top of the tube and push a star and the tissue down into the tube, seating it firmly against the black powder. Then I apply a thin ring of Elmer’s glue around the top edge of that section.

I then push section #2, bottom down, onto the glued section #1, and wipe any excess glue off with a paper towel. Then, while I’m pressing those sections together, I pick them up and lay them into the trough of the alignment jig. Pushing them down on the jig ensures that they are perfectly aligned, and I push them together end-to-end to make sure the glue joint holds tight.

Then I carefully pick them up, continuing to press the sections together, and stand the assembly upright.

Again I load lift powder, tissue, and star, and run a ring of glue around the top of the tube. Then, I assemble section #3 in the same manner as #2.

I repeat this process until all nine sections have been assembled and I have the whole shebang resting in the jig.

I could just press the sections together end-to-end, make sure they’re sitting nice and straight on the jig, and let the glue dry. But, nooo, not me. I’m a bit more of a perfectionist than that.

Note: That’s kind of a funny revelation. When I was a kid, my Dad was always hollerin’ at me for not cleaning up his shop after using his tools, or for not finishing up a project I’d started. Now, with my pyro avocation, I’ve gotten very particular about cleanliness in my shop in order to prevent serious accidents. And I’ve also come to know that meticulous work habits are a sure way to achieve consistency with my artistic fireworks devices. We live and learn. Sorry, Dad, and thanks; I finally got it!

So, I go one more step to really clamp the candle sections tightly, end-to-end as the glue dries, and to ensure my candle ends up perfectly straight when it’s dry.

I lay another piece of the aluminum angle channel on top of the glued-up candle. (You were wondering what that extra piece was for in the pictures above, right?)

Then I take 12-inch pieces of masking tape and put bands of the tape, stretched tightly with the sticky-side-out, around the aluminum and candle sandwich. This really holds the glued tube sections nice and straight.

To really pull the tube sections tightly together as the glue dries, I install two 1/2-inch square, 4-inch long, pieces of steel bar, and two tightened strap clamps. Gently tightening the clamps snugs the tube sections together, but I don’t tighten them so much that the ends of the tubes are damaged.

Of course, long rubber bands or elastic bungee cords could be used in place of the strap clamps. Pieces of wood could also be used instead of the steel crossbars.

It takes 2-3 hours for the glue to dry sufficiently to allow the assembled candle to be removed from the jig. I remove the strap clamps and steel bars, tear the bands of masking tape, which remove easily because they were applied, sticky-side-out. Et voilà! A sturdy, straight Roman candle emerges.

A little 100-grit sandpaper quickly knocks any rough spots off the outside of the tube joints.

Well, let’s stick a piece of Visco fuse into this puppy, take ‘er outside, and fire it up. Right?

Hold on there, podnah. Not so quick. The candle tube, as it currently is, really is not that strong yet. End-to-end glue joints don’t have much structural integrity. If this particular Roman candle is going to survive the pressures when it fires, those joints will have to be reinforced a teensy bit.

Enter fiber-reinforced, gummed, kraft-paper tape. One of my favorite supplies is a tape that I get from Staples: 2.8-inch wide, fiberglass reinforced, paper packaging tape, Staples #468231. This stuff is light, thin, and really molds well to the tube once it’s wet.

Although I usually cut the tape to length with scissors because of the fiber-reinforcement, I use my manual tape dispenser as a wetting station to wet the tape. A sponge could also serve this purpose.

The glued-together candle is 18.5-inches long. I cut four 18-inch strips of the kraft tape to use to reinforce the tube. Each strip will run lengthwise on the tube, and will wrap around to cover about 3/4 of the tube circumference. Therefore, the four strips, staggered as they are applied, will create 3 complete layers of tape on the candle.

I run a strip of tape through the dispenser’s wetting station, and carefully apply it lengthwise on the Roman candle tube. Each strip has to be kept straight; the long edge of the tape needs to be parallel to the length of the tube. I get the first strip pasted down tight. Then, I butt the long edge of a new strip right up against the edge of the first piece of tape. Since each strip only wraps around 3/4 of the tube’s circumference, once it is pasted down, the second piece of tape will overlap the first one some. I repeat this process for all 4 pieces of tape. That way the gaps in the tape get staggered around the circumference of the tube.

In between each strip application, I burnish the previous strip down nice and smooth with a scrap of paper tube. When all the strips are on, I give the whole tube a nice hard burnishing to produce a flat, smooth application of all the tape.

Oh, yeah, that baby’s looking nice, and feeling strong now. After inserting a hooked piece of Visco fuse as shown in the candle cross-section sketch, I put on a wrapping of colorful paper, and tie the paper snug around the fuse. Now she’s ready to take out, tape to a stake in the ground, and light.

You might be thinking, “That was a lot of work to produce one, simple fireworks device, wasn’t it?”

Naah. Not really. There was probably about an hour’s worth of work in the construction of that one candle, all told. It may sound like a lot of time and effort, but once you get going on the project, it’s really not that complicated.

This new Smith Method of making Roman candles is such an improvement and can produce such nice consistent results for the hobbyist, that I just can’t help but be excited about it, especially after my past, less satisfying results.

When I carefully look at the videos of all the Roman candles I made using this new method, every initial delay after ignition was just about exactly 4 seconds, and every intermediate delay was within one second of 8-seconds long. It don’t get no better than that.

On top of that, I’m already imagining creative variations on the above theme: mine-shot candles, crossette-comet candles, color-to-report-insert candles, married-comet ones, matrix-comet projectiles, and crackling-microstar-comet varieties.

I hope to tackle those projects in the coming months.

Additionally, the Roman-candle competition at the PGI (Pyrotechnics Guild International) convention allows candles up to 2-inches ID. I do have some nice, stout 1.5-inch ID tubes, so I just may have to come up with some larger versions of these babies to take to Mason City, Iowa in August.

Have fun and Stay Green,
Ned
ngorski@skylighter.com

How to Make a Fireworks Strobe Rocket

What is a Strobe Rocket?

If I had to make the choice of being able to construct only one type of rocket, it would be a difficult decision. I truly love the low-level simplicity and effect of the Spectacular Glitter-Tailed Rocket with Willow-Diadem-Horsetail Finish.

But for pure, high-powered, awe-inspiring and crowd-pleasing rocketry display, the strobe rocket is sure hard to beat.

The following video is a six-pound strobe rocket. I constructed this 1.5-inch ID model in a seminar I taught at a local pyro club event.

Note: The “one-pound” and “six-pound” rocket motor designations have nothing to do with what the rocket actually weighs. They are fireworking terms, which refer to the rocket engine tube’s inside diameter (ID), and have their roots in antique rocket-making terminology.

That baby was really up there by the end of its flight. You can tell that from the delay between the video and audio of the report heading. These large strobe rocket engines really do sound like helicopters in flight, too. For such a relatively simple fireworks device, they sure are satisfying and attention grabbing when they work well.

Even when they don’t “work well,” and CATO (blow up) on the launch pad, these rockets are impressive! There is a lot of power packed into that engine tube, so it pays to put a long piece of Visco fuse on them, and have everyone plenty far away from the launch area just in case.

This is the third in a series of whistle-related articles. The first installment dealt with making whistle fuel and simple fireworks whistles. That same fuel will be used in these strobe rockets. The second article described the construction of basic whistle rockets. Many of those same techniques will be used now to make strobe rockets. So, it’s a good idea for you to familiarize yourself with those basic methods before forging ahead with this project.

Note: I will not be repeating all the basic construction details from the whistle rocket tutorial. You really will need to be familiar with those techniques if you are going to tackle this strobe rocket project.

A strobe rocket utilizes whistle fuel for power, along with strobe fuel to create the popping sound and flashing light that is unique to them.

Pressing Rockets

Note: Once again, as in the whistle projects, hand ramming with a mallet is never employed with these fuels and devices. Only a press equipped with a safety shield should be used to press these items. Fireworks Tips #121 detailed the construction of such a hydraulic rocket press. For small rockets, some folks use a manual arbor press to consolidate (press) the fuels.

Strobe Rocket Fuel

In addition to the whistle fuel I referred to above, one other fuel is necessary for these strobing rockets–strobe fuel. This fuel is very similar to the composition that was used to make strobe pots. Please study the methods and precautions that were spelled out in that essay.

This strobe fuel is what gives these rockets their distinctive popping sound and flashing light as they fly. But, strobe fuel alone is not powerful enough to make a rocket fly.

Back in the ’80’s, Doc Barr started playing with a basic strobe rocket, using a black powder fuel to boost the strobe fuel’s power. His results are chronicled on Page 58 of The Best of AFN II.

A funny and educational quote from Doc’s article is, “All rockets have the potential of exploding on takeoff, but these do it with an annoying frequency. About 1 out of 10 act more like an open-ended salute than a rocket. So ‘light fuse and retire quickly’ is my Eleventh Commandment.”

In the late 80’s and early 90’s, folks like Doc and Steve LaDuke started working with whistle fuels in rockets, resulting in the high-powered fireworks whistle rockets like I described in the whistle rocket article mentioned above.

Somewhere along the line, these rocketry pioneers had the bright idea to combine the powerful whistle booster fuel with the impressive strobing fuel, and the modern strobe rocket was born.

Traditionally, nitrocellulose (NC) lacquer is added to the standard white strobe composition specified in my strobe pot article. In his BAFN article, Doc Barr said he pressed his strobe fuel slightly dampened with NC lacquer. Many modern builders dampen their fuel with NC lacquer, granulate the dampened fuel through a 12-mesh screen, and dry the granules before pressing the fuel in the rocket motor.

Years ago I made a slight change in this method. Rather than using NC lacquer, I now dampen my strobe fuel with an additional 2% mineral oil dispersed in Coleman Fuel, as I described in the whistle-fuel procedure.

Chemical	Percentage	16 Ounces	450 Grams
Ammonium Perchlorate	0.57	9.15	257.1
Magnalium, 200 mesh	0.24	3.8	107.1
Barium Sulfate	0.14	2.3	64.3
Potassium Dichromate	0.05	.75	21.5
Mineral Oil	+0.02	0.3	9

Note: The ammonium perchlorate, barium sulfate, and potassium dichromate are each milled individually in a blade-type coffee mill until they are fine enough to pass through a 100-mesh screen.

Warning: Potassium dichromate is toxic and a known carcinogen. A good respirator and rubber gloves are required when working with this chemical, and when using it in pyrotechnic compositions. Don’t breathe this stuff or get it on your skin. Wear your protective gear even when you are pressing the finished fuel in the rocket motor.

I’ll be making 3/4-inch ID (one-pound) size, strobe rocket motors. Each motor will use about 39 grams of whistle fuel and 25 grams of the strobe fuel. So, the 450-gram batch of strobe fuel shown in the formula above will be enough for approximately 18 motors.

All the dry chemicals are weighed out individually, then mixed thoroughly by gently passing them through a 20-mesh screen or kitchen colander. I put this mixed powder into a small plastic bucket.

I weigh out the mineral oil into a clean quart jar, such as a spaghetti sauce jar, and then I add 1/2 cup of the Coleman Fuel to the oil. After tightly screwing the jar’s lid on, I shake the liquid to completely mix the two ingredients.

This mixed liquid is then added to the dry powder, and it is completely blended in with gloved hands. The damp composition is then dried over a pot of hot water, as described in the tutorial on making whistle fuel. Once again, the fuel is never brought anywhere in the vicinity of any open flame or source of sparks.

After a couple of hours of drying over the pot of warm water, the fuel will be dry, will stop smelling of Coleman fuel, and will resemble grayish-green sand. I use my gloved hands to break up fuel clumps as it is drying.

The Rocket Tooling

To make the 3/4-inch ID strobe rockets for this project, I’ll be using my tooling, which is very similar to the Skylighter TL1361 tool set. Strobe rocket tooling is almost the same as whistle rocket tooling. The main difference is the spindle is about twice as long. The number of rammers (”drifts”) can vary from tooling to tooling.

Just as I did in the whistle rocket project, I polish the drifts and spindle using very fine sandpaper and metal polish to facilitate removal of the drifts during the pressing.

Strobe Rocket Motor Tubes

Once again, because of the high pressures used to make these engines, and the high thrust they develop, I use the extra-strong TU1066 3/4-inch ID paper tubes. For these motors I cut the tubes 6 inches long.

The Tube Support

A 6-inch long, PVC plumbing pipe and band clamp tube support is used to reinforce the paper tube during construction.

Drilling the Fuse Hole

Just as I did with the whistle rocket motors, I drill a 1/8-inch hole through the side of the paper engine tube, right where the bottom of the fuel grain will be.

Marking the Tooling Drifts for Safety

At least 1/8-inch clearance is allowed between the spindle and the point where the drifts would contact it. I mark my tool drifts with masking tape to be absolutely sure they never pinch fuel between the drift and the spindle while the fuel is being pressed. Pinched fuel can explode upon pressing. That 1/8-inch clearance is enough to prevent this.

My particular tooling set only has one hollow rammer and one solid rammer. Some tooling comes with two or three hollow drifts, and each one must be marked with tape accordingly for safety.

Pressing a Strobe-Rocket Motor

The first thing I do in this pressing process is scoop out a paper cup full of whistle fuel, and a paper cup full of strobe fuel, set them aside and put the large tubs of my fuels away in safe storage. As I’ve mentioned before, this is perhaps the most important safety precaution: limiting the amount of exposed flammable composition when working with it.

For my strobe rocket, I press the whistle fuel in the tube in the same way and with the same pressures I did when making the whistle rocket motors. Pressing three 7-gram increments, and one 4-gram increment of the whistle fuel brings that fuel halfway up the spindle. These increments are pressed with the hollow rammer.

I use black rubber o-rings on my rammers to keep dust down to a minimum during the pressing. These o-rings, as seen at the top of the solid drift in the photo of the tooling above, also serve another purpose.

Each time the rammer is about to be reinserted into the tube, I slide/roll the o-ring down toward the end of the rammer. Then, as I insert and press the drift down into the tube, the o-ring seals against the top of the tube and prevents much dust from blowing out. When the drift is removed after that increment, the o-ring’s position marks where the top of the tube was, and just how far into the tube the drift went while pressing that increment.

When the drift is removed from the motor after an increment is pressed, the o-ring stays put on the drift exactly where the top of the motor tube was before the drift was removed.

Critical: I keep a full-scale sketch of the motor on my workbench as I’m pressing the motor. I’ll put the drift, with the o-ring marking where the top of the motor tube was, down on the sketch, and keep track of how high the pressed fuel is coming in the motor. In this way I can precisely determine when the whistle fuel is pressed up to the desired level, and switch to the strobe fuel increments.

I keep the hollow rammer cleaned out as I press the fuels, because I never want to be pressing fuel up inside the rammer, between it and the spindle.

Then I press three 7-gram increments of the strobe fuel with the hollow rammer, and one 4-gram increment of that fuel with the solid rammer, being very careful to not press past the safety-tape line on that rammer.

This brings my strobe fuel up to about 3/16-inch to 1/4-inch above the end of the spindle, as checked once again by comparing the drift and o-ring with my sketch. The final strobe fuel increment is adjusted so that it reaches that level.

This strobe-fuel distance above the spindle is critical. Too little strobe fuel will cause the motor to start its whistling delay burn too soon. Too much strobe fuel above the spindle will cause the motor to burn too long, turn back toward earth, and perhaps even return all the way to the ground before the heading bursts.

Note: Ask me sometime how I know about the effect created when too much strobe fuel is pressed above the spindle. The story deals with a six-pound strobe rocket coming back to earth, going through the roof of a meeting tent as there was a “parting of the seas” in the crowd, bouncing off a swimming pool diving board, and the heading explosion nearly scaring Doc Barr to death, or at least into regaining the memory of most of his previous sex life. Oh, I can laugh about it now, but it was damn embarrassing at the time.

After the strobe fuel has been pressed to that critical distance above the spindle, another two 7-gram increments of the whistle fuel are pressed above the strobe fuel, as shown in the sketch above. This whistle fuel section creates the whistling “delay” portion of the rocket’s flight before the ignition of the header.

As I mentioned in the whistle-rocket article, other “delay” effects can be produced. Colored fuels can be used instead of the whistle delay fuel, or titanium can be added to the whistle delay fuel. The amount of delay fuel has to be dialed in to produce the desired effect and length of flight.

The motor is then capped off with a 7-gram increment of bulkhead clay, with a passfire hole hand-twist-drilled into it. I never drill into whistle fuel with titanium in it, as I warned in the whistle-rocket article.

If I do use whistle fuel containing titanium in the delay section, I cap it off with 1/8-inch of fuel with no metal in it. Then I carefully hand-twist-drill the passfire hole.

Troubleshooting: The various amounts of fuel, and the distance up the spindle between the two fuels, have been dialed in for my own fuels and tooling. If your pressed rocket motor blows up on the launch pad, then less whistle fuel and more strobe fuel should be used. On the other hand, if your rocket doesn’t have enough power at launch, more whistle fuel and less strobe fuel should be used.

So, there we have it, a finished strobe-rocket motor. One final thing I’ll do is carefully re-enlarge the fuse hole with my awl since the hole can become a bit closed down and filled with fuel during the motor’s pressing.

Creating a Rocket Header

These rockets can fly so high that I really like to only use report headers on them. The effect of a star-shell header could get lost up at that altitude. As I showed with the whistle rockets, the hollow end of the motor tube can be filled with loose whistle fuel, perhaps containing some titanium, and then capped off to create a small report heading.

Loose strobe fuel, which is also a powerful explosive, can be used in this way, too. If more hollow space is desired, the motor tube can be extended with an extra piece of the same motor tube, glued and taped onto the motor tube to extend it.

For a larger, more impressive report heading, Skylighter’s PL1020 or PL1022 plastic #5 can shell casings can be used. These plastic cans measure slightly less than 2 inches in diameter, and work well on these one-pound rockets.

I fill the recess in the can’s cap with hot glue, drill a quarter-inch hole in the can’s bottom, and hot-glue a piece of quickmatch or fast fuse into that hole. When gluing the fuse into the can, I make sure all the gaps around the fuse are filled with glue to prevent any composition from leaking out of the can after it is filled.

The fuse will transfer fire from the top of the rocket motor to the heading.

Then I fill the can with my report composition of choice. The traditional filling would be flash powder, but making flash has become a bit problematic for some in the current legal climate.

If one has legal access to the necessary chemicals, I’ll describe a safe way to make a flash report with one of these cans. But first, I’ll detail three alternatives for making a report without flash powder.

A simple report can be made by filling the can with black-powder-coated rice hulls, with the addition of some coarse titanium if silver sparks are desired. One of the cans can hold 45 grams of the BP-coated hulls, and 14 grams of the titanium.

Two other alternatives would be to fill the can with loose whistle fuel or loose strobe fuel. A can will hold 57 grams of my whistle fuel, or 67 grams of my strobe fuel. For silver sparks, 14 grams of titanium can be added to either of these fuels by putting the fuel and the titanium into a small paper cup and gently swirling the two together to mix them before pouring them into the can.

Note: I mention this flash report composition option out of a sense of responsibility. Folks will make flash reports. There is a long tradition of it in all kinds of fireworks. But, flash powder is the most powerful composition that fireworkers work with, and many really serious pyro accidents involve it.

No matter which report composition I used, I then glued the caps onto the plastic casing cans with PVC plumbing cement from Home Depot. I did this outdoors because of the fumes, wiping the excess glue off with a paper towel.

I then strengthened the casings with some 1/2-inch wide fiberglass-reinforced strapping tape. Since my tape roll was 1-inch wide, I split the end of the tape in half. This allowed only one half of the width to tear off as I used it.

Note: During this taping process, the normal handling of the binary-mixed flash report is enough to sufficiently mix the ingredients. No rough shaking is necessary. Once the can is closed, handling this report is no more dangerous than the normal handling of a commercial fireworks salute.

I then finished the headings off with a layer of aluminum foil duct tape.

Here is a video of each of the four different report compositions, made as described above.

Attaching a Heading, Fuse, and Stick to a Strobe-Rocket

I first trim the header fuse so that it is long enough to go all the way through to the bottom of the passfire hole, and is pressed against the rocket’s fuel grain. I bare the last 3/4 inch of the fuse.

Then I put a bead of hot glue around the top of the motor tube and quickly install the header, carefully making sure the fuse goes all the way down into the passfire hole as I do so. I reinforce the joint between the header and the motor tube with an additional fillet of hot glue.

I’ve found that the slick side of a piece of the paper backing from the aluminum foil duct tape comes in handy for smoothing fillets of hot glue without burning my fingers.

The joint is then reinforced with some vertical, 3-inch strips of strapping tape, finished off with horizontal bands of the tape around the heading and the motor tube. This really strengthens the connection.

A 45-inch long, 5/16-inch-square, poplar rocket stick, with a beveled end, is then hot-glued and strapping-taped to the motor. If the rocket is to be flown immediately, then a 6-inch piece of Visco fuse is inserted into the motor’s fuse hole.

If I am going to store the motor for a while before launching it, I won’t install the Visco fuse now, but will instead seal the end of the motor and the fuse hole with aluminum foil tape to prevent the whistle fuel from absorbing moisture.

Well, it’s been a bit of a journey, but in the last 3 projects we’ve made whistle fuel, whistles, whistle rockets, strobe fuel, strobe rockets, and impressive report headings. While these powerful fuels and devices are not exactly beginner’s projects, if they are approached one step at a time, with good safe work habits, they can indeed be some of the most impressive and satisfying fireworking devices around, both for the builder and for the audience.

Stay Green and Have Fun,
Ned

How to Make Fireworks Whistle Rockets

What Is a Whistle Rocket?

I think a really impressive fireworks device speaks for itself, so here’s a video of one of these whistling firework rockets in action.

A whistle rocket does just that: whistles and screeches as it leaps skyward. The motor uses the same whistle fuel that was used in the “How to make a whistle” article. Whistling rockets are “hot.” They leap off the launch pad and can really reach a seriously high altitude if they’re made well.

I’ve made whistle rockets in sizes from 1/4-inch ID super-bottle-rockets up to 1.5-inch-ID “six-pounders.”

I’ve lifted some big ball shells (called “headings” when they’re carried by rockets) with the larger whistle rockets. But, often they fly so high that the effect of such a heading is lost. For that reason I prefer to simply put a large report heading on them with some coarse titanium in it for impressive silver sparks when the header explodes.

Other variations in construction can include various “delay” effects during the coasting portion of the flight following the initial powerful thrust portion–from simply allowing the rocket to continue whistling across the sky, to having the whistle change to a brilliant red flare or a color changing one, before the heading finishes the rocket’s flight.

Be aware, though, that whistle rockets are not your “father’s black-powder rockets.” The rocket fuel used in these babies is powerful. If the rocket engines are not dialed in carefully and fused properly, very impressive CATO’s (”bombs on a stick”) can result.

Warning: Do not EVER hand-ram whistle rockets using a mallet. The fuel is sensitive and could be set off in that process. Whistle rockets must be pressed using a manual arbor press for small rockets or a hydraulic press for larger motors, which require more pressure. It is wise to use a safety shield on a press just in case something goes wrong and the motor ignites during construction.

Whistle Rocket Fuel

I’ll be using the same fuel that I specified in the article on making whistles. The alternative fuels I mentioned in that essay can be used to make whistle rocket motors. But there will be the requisite “dialing in” in order to maximize performance and consistency with those variations.

So, study that article and make some of that whistle fuel, observing all the pertinent safety precautions.

Whistle Rocket Tooling

I will be making one-pound, 3/4-inch ID, whistle rocket motors for this project. Skylighter carries TL1311 tooling used to make these engines.

This tooling set comes with a base, a spindle, a hollow rammer for pressing the fuel increments around that spindle, and a solid rammer with which to press the increments of fuel above the spindle.

Note: You may notice the tooling I’m using in this project, which I’ve had for years, is different than the Skylighter tooling. But, my spindle is about the same size and the motor construction and performance are very similar.

Whistle Rocket Motor Tubes

Because of the high pressure at which the fuel is pressed in these motors, and the thrust they develop during flight, high-strength paper tubes must be used in their construction.

Skylighter TU1066 3/4-inch ID, 1/8-inch wall, extra-strong tubes are an excellent choice for these whistle rocket motors. I cut the 30-inch long tubes into 4.75-inch long tubes for these engines.

The Tube Support

Because of the high pressure used to press these motors, the tubes would bend, split, and collapse if they were made using no tube support. A good support is absolutely essential when making these motors.

A 4.75-inch piece of 1-inch ID, PVC plumbing pipe serves well as a tube support. It is sliced lengthwise with a hacksaw to ensure that it will go around the paper tube and fit snugly when the slice is closed. The support is held tight with metal band-clamps, installed side-by side, and tightened with their screw-adjusters alternated around the circumference of the support.

Polishing the Tooling

Unlike the fuels for charcoal tailed rockets, whistle rocket fuel tends to be “sticky.” The high pressures used to press the fuel around the spindle cause the fuel to adhere to it. This makes the motor hard to remove from the spindle once the engine is pressed. And the sodium salicylate fuel I prefer is reportedly stickier than fuels made with potassium benzoate or sodium benzoate.

Here is a solution, though, regularly touted by master-rocketeer Steve LaDuke. Polish your tooling, especially the spindle, using very fine, 600-grit sandpaper and a good metal polish. I got an excellent polish, Mothers Billet Metal Polish, at my local auto-parts store.

First, if I have any scratches or small imperfections on the spindle, I remove them using a small piece of the sandpaper to smooth the tooling. Sanding in a lengthwise direction on the spindle ensures any remaining scratches run in that direction, rather than in a circumferential pattern, which would make the motor-removal more difficult.

Then, using a small section of soft rag, the tooling, including the rammers, is polished until it all has a mirror-smooth finish. This really enhances the ease of use of the rammers, and the finished rocket motor’s ability to be removed from the spindle.

I even do the best I can to polish up inside the hole inside the hollow drift (”drift” is another word for “rammer”). This will help release any fuel which gets between that hollow part and the spindle during pressing.

Polishing the tooling this way is time well spent. It will help avoid a lot of aggravation in the next steps of pressing the motor and removing it from the spindle when it’s done.

Pressing a Whistle-Rocket Motor

Besides being pressed in a longer tube, and on a longer spindle, a whistle-rocket motor is not much different than a regular whistle. But I do fuse whistle rocket motors differently than I fuse standard whistles.

Drilling the Fuse Hole

You’ll note that the fusing technique shown in the diagram is different than most rocket fusing. There is a method to my madness.

The first thing you might notice is there is no clay nozzle in whistle rocket motors. A whistle rocket needs to have the bottom of its motor tube wide open. So the fuel has to be ignited right at its bottom edge, or else there’s a good chance the motor will blow up due to over-pressurization after ignition.

It can be a challenge to install a fuse from the bottom of the motor, only touching the edge of the fuel-grain, with no nosing to hold it in place.

Some folks hot-glue the fuse to the inside surface of the paper tube. Others use masking tape to attach the fuse to the rocket stick. I’ve tried both of those methods. With some care they can work fine, but at other times I’ve had the fuse fall off as it was burning, before igniting the motor.

So, I came up with the solution of installing the fuse as shown above. Before pressing any fuel, I drill a 1/8-inch hole through the motor casing, right at the outside edge of where the fuel grain will begin. I use a piece of wooden dowel to back up the inside of the paper tube during the drilling operation.

Marking the Tooling Drifts for Safety

Next, I mark the tooling drifts with masking tape to ensure they never come into contact with the spindle when I’m pressing a motor. I allow about 1/8-inch margin of safety between the drift and the spindle when I’m applying the tape.

Pressing Rocket Fuel into the Tube

The hollow drift is used to press the increments of fuel, until the fuel is above the spindle. All the increments are pressed to 7500-psi (pounds per square inch) on the composition.

In the article on making whistles, I illustrated the method for determining how much hydraulic press force to use with a solid drift. Applying 2200-psi of pressure according to my press’s gauge results in an actual 7500-psi on the composition with the solid drift.

But, since the hollow drift has the hole in it, less force will have to be applied to it to achieve this same pressure on the fuel.

With some math, I’ve determined that the surface area of the end of this hollow drift is about 80% of the surface area of a solid-end drift. For this reason, when using the hollow drift I’ll only apply about 80% of the force with my press that I’d apply when using the solid drift.

So, for the increments that are pressed around the spindle with the hollow drift, I’ll press up to a gauge reading of 1750-psi on my hydraulic press.

The first thing I do when pressing a motor is remove a small paper cup of the fuel from the tub of fuel. Then I close the tub tightly and set it aside away from where I am working. That way, only the small cup of fuel is exposed in case something goes wrong.

With the support securely fastened around the paper tube, and with the fuse-hole-drilled end of the tube mounted on the spindle, I introduce 7 grams (1/4-ounce) of the whistle fuel, using a funnel.

I then consolidate that fuel increment with the press in two steps, by first pressing up to only 1000-psi on the gauge.

I remove the drift and use the smooth, round end of my awl to clean any fuel that is wedged in there out of its hole. Then, I insert the drift back into the tube and press the rest of the way up to 1750-psi on the gauge.

If I press all the way up to the full pressure on the hollow drift in one step, fuel will work its way up between the drift and the tube, and between the spindle and the drift, in its hole. This can bind the drift in the motor, which makes it difficult to remove after the increment is pressed. Pressing the increment in two stages, and cleaning the drift between those two pressings usually eliminates stuck-drift syndrome.

When I’m pressing a really large motor, such as a 1.5-inch ID model, I’ll actually press each increment in 3 or 4 stages to reach the full pressure in order to keep the drifts from getting stuck.

Four, 7-gram increments of the fuel, pressed in this manner with the hollow drift, bring the fuel to just above the spindle, using my fuel and tooling. This can vary a little from batch to batch of the fuel, or with different tooling.

After the fuel is above the spindle, I switch to the solid drift. Now I press the same 7-gram size increments in one pass up to the full 2200-psi reading on my gauge.

For the rocket shown in the initial video in this article, I press fuel to one inch above the spindle. That requires three 7-gram increments with the solid drift, for a total of 49 grams of fuel in this motor.

I cap the motor off with a 7-gram increment of bulkhead clay mix.

Adjusting the Total Flight Time of the Whistle Rocket

The portion of the rocket’s flight after the initial high-thrust phase, and before the heading bursts, is called the delay section of the flight.

The fuel around the circumference of the spindle, and above it for that same distance, about 1/4-inch, burns very rapidly in the highly pressurized thrust period of the rocket motor’s burn.

Then, the solid portion of the fuel above that thrust fuel burns more slowly in a less pressurized environment. That’s why the whistle sound changes so drastically after the initial thrust burn.

So, in this rocket motor I had 1/4-inch of thrust fuel above the spindle, and then about 3/4-inch of delay fuel above that. If I shorten that delay fuel, the delay portion of the flight would be shorter. If I lengthen the delay fuel column in the motor, that delay portion of the flight would be longer.

Looking at the video at the beginning of this article, the one-inch of total fuel above the spindle produced that particular flight and delay before the heading exploded. I was pretty happy with that rocket’s flight. I might have lengthened the delay fuel column another 1/4-inch to see if that produced a more pleasing flight in the next rocket.

Other interesting modifications can be made to the delay fuel grain. Once the fuel has been pressed to above the spindle, spherical titanium can be added to the fuel increments that get pressed with the solid drift. The delay fuel is weighed into a paper cup. I add 10% of that fuel’s weight in titanium. Then the cup is swirled to mix the components.

The titanium fuel mix is pressed one increment at a time, the same as described above. The metal will produce a silver spark trail as the delay-fuel burns. If the hard metal is added to all the fuel (below the top of the spindle), it will tear the spindle up pretty quickly. Since it also might pose a sparking threat, I only add it to the delay fuel.

If I plan to have a passfire hole, I usually drill the hole down through the center of the clay bulkhead into the fuel. But, I don’t want to drill into any fuel containing titanium; so I’ll cap any titanium-fuel off with 1/8-inch of plain fuel (no titanium in it). Hand-twist-drilling into that is safer.

The effects you can create using the delay fuel are limited only by your imagination. For instance, in his article “How to Make Fireworks Rockets with Green and Red Tails,” Dave Stoddard describes delay fuels used to change the rocket tail’s color to a green or red flare as it flies upward.

Removing the Tube-Support from the Tube, and the Motor from the Spindle

After the fuel and clay have been pressed in the tube, it’s time to remove the motor from the spindle. This is easier if the support is removed from the engine first, which loosens the motor on the spindle just a tad.

First, I loosen and remove the metal band-clamps from the support, and then slide the PVC support off of the motor.

Then the motor is twisted off the spindle. Putting the spindle base in a vise or holding it rigidly in the rocket press can facilitate this. Using both hands to twist it, the motor is carefully removed from the tooling. Do not use clamps or pliers on the motor itself, or you will risk cracking the fuel grain, which will cause the rocket to explode instead of fly.

Drilling Passfire Hole into Clay Bulkhead

If I am going to put a heading on the rocket, then I’ll need a passfire hole in the clay bulkhead to transfer fire from the last of the rocket fuel to the heading.

I create this passfire hole by carefully hand-twisting a drill bit into the center of the bulkhead just through the clay into the pink fuel. (Remember that the last 1/8-inch of fuel that was pressed should contain no titanium, even if titanium was added to the rest of the delay fuel.)

Warning: Never use a power drill to create the passfire hole. The friction and heat caused by such fast drilling could ignite the motor. Only use hand twisting on the drill bit to create the hole.

I’ve found that starting the hole with a sharp 1/8-inch drill bit, hand twisted through the clay until it just barely penetrates the fuel, works well. Then I’ll expand the hole with a 1/4-inch diameter bit to widen and create the final passfire hole.

Simple Rocket Headers

Several types of simple headers can now be employed on this whistle rocket.

There is a 1-inch long empty space in the motor tube above the drilled clay bulkhead. First of all I like to insert a couple of pieces of black match, from either quickmatch or fast-fuse, into the drilled bulkhead passfire hole. I cut these pieces of match about 1.5-inches long so they reach the bottom of the passfire hole, and extend just to the end of the motor-tube.

These strands of blackmatch ensure positive fire transfer from the last of the rocket-fuel to the header.

For a spray of stars at the end of the rocket’s flight, a small amount of black powder can be put into the tube’s recess, followed by some of the stars.

For a falling glitter comet, some of the black powder followed by a single 3/4-inch comet can be used to fill the end of the motor.

For a small report at the end of the rocket’s flight, the end of the tube can be filled with either loose black powder or loose whistle fuel. A pinch of coarse titanium can be added to either of these powders to produce silver sparks when the header fires.

With any of these types of headings, the motor is then capped with a 1-inch end disk, glued on.

If a report heading has been made, I like to reinforce the report tube-section and end cap with some strapping tape, finished off with some peel-and-stick aluminum-foil duct tape. This reinforcement really helps a report heading to “pop.”

For a star or comet heading, simply gluing a paper disk on is sufficient to finish the end of the motor.

Installing Rocket Stick

The last step to finishing this rocket is to install the stick. I’m using a square poplar stick that I ripped on my table saw. It measures 5/16-inch square by 36-inches long. I bevel the end of the stick, hot-glue it straight on the motor, and finish the attachment with two bands of strapping tape. I make sure the stick does not cover the fuse-hole.

A 6-inch piece of Visco fuse can now be inserted into the fuse hole, and the rocket is ready to be placed in a launch tube and flown.

Sealing the Rocket Motor for Storage

If I’m going to store the finished rocket for a while, I like to seal the bottom of the motor and the fuse-hole with some aluminum-foil duct tape. This prevents the hygroscopic rocket fuel from absorbing atmospheric moisture during storage, and protects the motor from flame or sparks until flight-time.

Prior to flight, the tape is completely removed from the motor’s bottom, and the Visco fuse is installed through the fuse hole.

Motors without sticks can be stored in sealed plastic baggies along with a bag of desiccant to ensure they do not absorb moisture.

Conclusion

Well, there you have it–one of the most interesting and powerful rockets you can make.

Next time I’ll show you a nice variation on this basic motor, the strobe rocket, and some different ways to create a rocket heading.

See ya then,
Ned

How to Make Pyrotechnic Whistle Mix

Weighing and Screening Pyrotechnic Chemicals

How to Make Flashing Fireworks Strobe Pots

Introduction

Close your eyes and listen to this music. What do you see when you do so?

Click here to listen to The Who

If you don’t see a large fireworks mine-shot, followed by a line of 30-second strobe pots, ending with another large mine-shot, then you really need to be subscribed to the Quilting-101 newsletter instead of this one on making homemade fireworks.

Man, that music gets me in the mood for strobes. The first mine-shot would grab the attention of any fireworks-display audience. Then the soft and subtle section of strobes would calm them down and get them ready for their emotions to build during the show.

Strobe pots are among the simplest of fireworks devices and are easy to make. They can really add some of that low-level variety to a pyro-display that so helps to keep an audience’s attention.

“Hey, here’s something different,” they’ll say to themselves as they stop, settle in, and start to pay attention.

How do these pyrotechnic “twinklers” work?

It is not necessary, of course, to have a scientific understanding of strobes in order to make them. Like baking a loaf of bread, chemistry is not necessary. All you need is a recipe, the right ingredients, and a feel for the proper ways to manipulate those ingredients.

But, for the scientifically minded, there are a few informative resources, which explore the strobe phenomenon in depth. In the 1979 edition of Pyrotechnica, Number 5, Robert Cardwell, the editor and publisher of the Pyrotechnica series, wrote an article, Strobe Light Pyrotechnic Compositions: A Review of Their Development and Use.

In this essay, Cardwell explores the historical development of strobing compositions and presents quite a few different formulas.

Dr. Takeo Shimizu, in Fireworks, the Art, Science and Technique (FAST), originally published in 1981, writes about “Twinklers,” which is how he refers to strobing stars. He presents an outline of the development of these strobing compositions, progressing during the second half of the 1900’s.

Specifically Shimizu writes, “In Germany, U. Krone and F. W. Wasmann suggested that a twinkle composition consists of two kinds of compositions mixed with each other, i.e. a smolder composition and a flash composition-Ammonium perchlorate smolders when it is mixed with a small quantity of magnesium. This can be used for the smolder composition. A mixture of magnesium and sulfate flashes when it is heated to a high temperature. This can be used as the flash composition.”

So, interestingly, a strobe composition is actually a mixture of these two types of comps, a smoldering one and a flashing one. When the mixture is lit, the first one begins to smolder. When the heat rises high enough, the flash comp ignites and emits a flash of light and heat. Then the mass returns to the smoldering state until the heat rises high enough to repeat the flash.

In some compositions, magnesium-aluminum (magnalium) is used instead of the magnesium. Magnesium requires a coating to prevent it from prematurely reacting with the oxidizer in the comp.

Additionally, sometimes barium nitrate or other oxidizers are used instead of ammonium perchlorate.

In 1987, John “Skip” Meinhart offered some details about his noteworthy strobing star formulas in Pyrotechnica XI. Except for Shimizu’s White formula, and Skip’s Pink formula, all the rest of the formulas use magnesium as the metallic fuel ingredient.

In the 1992 Pyrotechnica XIV edition Jennings-White explores Blue Strobe Light Pyrotechnic Compositions. Up until that point in time, blue strobes had not been explored in depth because of some unique problems associated with the chemical mixtures required to produce that color in a strobe.

All of this information ought to be able to keep you reading until late into the night if you are so inclined.

Making strobe pots

I won’t be focusing on making strobing stars in this project, but only simple, ground-effect strobe pots.

I’m also not going to be making any of the formulations, which contain magnesium. As I said, using that metal requires a special coating process because it does not form an oxidized protective layer on its own, as do aluminum or magnalium.

There seems to be some debate as to whether or not magnalium needs to be treated and coated when it is used in compositions containing ammonium perchlorate. Meinhart states, “I have had success using magnalium powders that have not been treated with potassium dichromate. In practice I have often used treated metal powders, but this does not always seem to be necessary.”

Whereas in Hardt’s Pyrotechnics, Barry Bush notes that the formulas he cites which contain magnalium or magnesium in combination with ammonium perchlorate do “require the metal powders used to be treated with potassium dichromate.” Shimizu also specifies treated magnalium, and details the methods of treatment in FAST.

Shimizu does state that if there is any reaction between magnalium and ammonium perchlorate, which would be encouraged by the presence of water, it would only be a slow reaction in which the metal is affected gradually.

I have used untreated magnalium in these formulas, with no problems. One sign of an unwanted reaction would be the heating-up of the composition as I’m working with it, so I always pay attention to see if that is occurring. I avoid adding any water to such a composition. I also don’t store these devices for long periods of time, which could produce a slow reaction of the ingredients, especially in the presence of moisture.

So, I think I’ll make simple white and pink strobe pots. The white formula is the most commonly cited one:

White Strobe Composition

Chemical	Percentage	16 Ounces	450 grams
Ammonium perchlorate	0.57	9.15 ounces	257.1 grams
Magnalium*	0.24	3.8 ounces	107.1 grams
Barium sulfate	0.14	2.3 ounces	64.3 grams
Potassium dichromate	0.05	0.75 ounces	21.5 grams

* Shimizu specifies 80-mesh, whereas other sources specify 100-200-mesh. The mesh of the metal is known to vary the flash rate of the strobe, so some experimentation is in order. Initially, I’ll be using 200-mesh magnalium, Skylighter #CH2072.

Barry Bush has an interesting note in Pyrotechnics concerning this formula. This formula “may be given a faster frequency by replacing the barium sulfate with anhydrous magnesium sulfate. The resultant fast strobe is sometimes called a “shimmer effect.” I’ll have to try this sometime in aerial-shell strobe-stars, since it is an effect I have admired in commercial shells.

Additionally, the flame created by this “white” composition is brilliant, but it does have a very slight green tint caused by the barium. Barium normally produces very green flames with the addition of a chlorine donor such as parlon or saran. Another experiment would be to include small amounts of these chlorine donors to shift the color of the white strobe pots to green.

The pink strobe pot composition is as follows:

Meinhart Pink Strobe Composition

Chemical	Percentage	16 ounces	450 grams
Ammonium perchlorate	0.57	9.15 ounces	257.2 grams
Magnalium, 200 mesh	0.15	2.45 ounces	68.6 grams
Strontium sulfate	0.11	1.85 ounces	51.4 grams
Strontium carbonate	0.08	1.2 ounces	34.3 grams
Parlon	0.04	0.6 ounces	17.1 grams
Potassium dichromate	0.05	0.75 ounces	21.4 grams

All the chemicals (except the magnalium, which I don’t put through fine screens) are fine enough to pass through a 100-mesh screen. If they are not, they are milled individually in a blade-type coffee mill.

Note: Ammonium perchlorate does not play well with potassium nitrate. The combination forms ammonium nitrate, which is very hygroscopic, attracting moisture out of the air like crazy, rendering any mixture or composition containing it wet and useless. Don’t grind either of these chemicals in a coffee mill which has been used on the other chemical, unless the mill has been thoroughly cleaned with soap and water.

Warning: Potassium dichromate is toxic and a known carcinogen. A good respirator and rubber gloves are required when working with this chemical, and when using it in pyrotechnic compositions. Don’t breathe this stuff or get it on your skin.

All the chemicals for a given formula are weighed out individually and are passed through a 20-mesh screen 3 times to thoroughly mix them.

Then the composition is mixed with enough nitrocellulose (N/C) lacquer (Skylighter #CH8198P) to create thick putty, similar to Play-Do. I did not dilute the lacquer, but used it right out of the can, as-is. The one-pound batches required 3 ounces, by weight, of the lacquer.

I started mixing the composition in a plastic tub with a paint stir-stick, and finished by kneading it with gloved hands.

The dough is then pushed with gloved fingers into paper tubes to create strobe pots. I start this process by pushing the tube into the composition-putty to get the filling started.

Large pots can be made with 1.5-inch ID tubes, cut into 1.5-inch long sections. Or, smaller pots can be made with 3/4-inch ID tubes, cut into one-inch long sections, or even longer. While thicker-walled parallel tubes, like rocket tubes can be used, strobe-pot tubes do not need to be super-strong, so spiral-wound tubes like Skylighter #TU2142 or TU2053 can be used.

Large diameter strobe pots would be appropriate for large displays and venues. Smaller ones are nice in backyard size shows. Varying the length of the paper tube will adjust the total burn-time of the strobe pots, so their duration can be dialed in for specific uses.

For this project, I think I’ll make mostly 3/4-inch ID by 1-inch long strobes to determine how well they are working and how long they burn, plus a few other sizes to see how they perform, too.

Once the composition has been stuffed into the paper tubes, they are placed on their sides and set aside on a tray to dry out in the open air. N/C lacquer releases acetone and other highly flammable solvents as it dries, and I don’t want these vapors collecting in my shop as this occurs.

Toward the end of the tube filling, the remaining strobe-putty started to dry out and became difficult to consolidate into the tube. I added just a touch of acetone to the composition to re-dampen it.

It took 3 or 4 days for these pots to dry completely. When I tried to burn them before they were completely dry, they did not burn with a regular strobing-action, but with a more continuous flame.

Priming the strobes

The dry pots will light well if they are ignited with a piece of Visco-fuse or with a propane torch. But if I want them to ignite reliably with a fast-fuse or quickmatch line of fuse, then I need to prime them.

A black powder prime containing potassium nitrate cannot be used on these compositions because of the incompatibilities between the nitrate and the ammonium perchlorate.

In FAST, Dr. Shimizu lists a different prime specifically for this use.

Ignition Composition for Twinklers

Chemical	Percentage	16-Ounces	450 Grams
Potassium perchlorate	0.74	11.85 ounces	333 grams
Red gum	0.12	1.9 ounces	54 grams
Charcoal, airfloat	0.06	0.95 ounce	27 grams
Potassium dichromate	0.05	0.8 ounce	22.5 grams
Aluminum*, flake 100-325	0.03	0.5 ounce	13.5 grams

*Skylighter #CH0174 aluminum would fit the bill in this prime.

After making sure all the individual chemicals (except the aluminum) will pass through a 100-mesh screen, I weighed them out individually and mixed them together by passing them through the 20-mesh screen three times.

I weighed out 1 ounce of the dry strobe prime composition, and added 1 ounce (by weight) of the nitrocellulose lacquer. This created a wet prime comp that had a consistency between that of honey and peanut butter.

I used a wood stick to apply this wet prime to one end of each strobe pot, and quickly pushed that wet end into some dry strobe composition for the final prime layer.

I perform one final operation to finish the individual strobe pots. I hot-glue a paper disc onto the bottom of each pot. This prevents sparks and/or slag from dropping and igniting the bottom of a twinkler prematurely as the pot burns. It also facilitates mounting the pots to a board when a show is being set up.

Mounting and fusing strobe pots for use in a fireworks display

Once the individual strobe pots have been completed, they can be mounted to a board and fused for easy installation out in the field prior to a fireworks show.

To do this, I simply hot-glue the pots to a board at the desired spacing. I find a spacing of 4 feet on-center to work well. Then a run of quickmatch or tape-covered fast-fuse
is used to fuse all the pots together. A “window” is opened up in the quickmatch-pipe, and the bared black-match is taped on top of the strobe pot with 3 wraps of masking tape.

The quickmatch can be ignited by a piece of Visco-fuse, or an electric igniter can be employed, per the information in How to Make Electric Matches and Wiring Fireworks and Firing Systems in a Fireworks Display.

Results

I burned white and pink strobes made with the 200-mesh magnalium. The white one burned for 15 seconds with a very fast strobe rate of about 10 flashes per second. The pink one actually looked red, burned for 23 seconds, and flashed about 4 times per second.

Warning: These strobe pots burn with an extremely brilliant flame and light. It is best to avoid looking directly at them to prevent eye damage. Placing the pots where their light can reflect off of a structure or trees makes their effect visible without having to look directly at them.

Click here to see a video of the white and red strobes.

I liked the performance of the pink/red strobe, but the white one flashed too rapidly for my taste.

So, I made a new batch of each color using 60-mesh magnalium. I know that using a larger granulation of the metal will slow down the burn time and also its strobe frequency.

Burning these new strobes produced the following results:

White strobe with 60-mesh magnalium, burned for 25 seconds, and flashed 1.5 times per second. I found this to be a very pleasing strobe frequency.

Red strobe with 60-mesh magnalium burned for 27 seconds, flashed at a rate that varied from slow to fast. This pot just couldn’t seem to find a groove and settle into it.

Check out the video of these two types of strobe pots:

Of the four variations I prefer the white strobe pots made with the 60-mesh magnalium, and the pink/red twinklers made with the 200-mesh magnalium.

Although I made mostly 1-inch long twinklers, I also made some larger ones. Two-inch long ones, made in the 3/4-inch ID tubes, burned as follows:

• 2-inch white strobe with 60-mesh magnalium burned for 40 seconds with about 2.5 flashes per second,
• 2-inch long red strobe with 200-mesh magnalium burned for 40 seconds with flashes varying from slow to fast again.

And, last but not least, I rigged up some white strobe pots using 60-mesh magnalium on a board and accompanied them with the music I linked to right at the beginning of this article. You can get the idea of what I had in mind in the first place as a nifty addition to a fireworks display. Click the video below of the three white strobe pots accompanying Who’s Won’t Get Fooled Again.

I do like what these simple, low-level ground devices can contribute to a fireworks show.

Enjoy,

Ned

How to Make Chinese Sky Lanterns

Can mere mortals make sky lanterns?

I gotta admit, I’ve seen sky lanterns around for several years. I’ve seen ‘em advertised right here by Skylighter. Have seen them at displays and club events. But, honestly I never gave them much thought, and I wasn’t much tempted to buy any.

But, then I saw the latest Skylighter ad for them, and I thought, “I wonder how sky lanterns are made.” Ya see, one of the things I enjoy most is learning how something is made. I watch This Old House and The New Yankee Workshop, just to see how they do stuff, even though I’ve been doing that kind of work myself for a living for 30 years.

So, I had Harry send some of the flying lanterns to me. By the time they arrived on my doorstep, I was excited to see them. I opened the package up, looked at the treetops to make sure there wasn’t too much wind blowing, and I hustled my wife and granddaughter outside to fire the first one up.

I enjoyed finding out how to light the paper lantern, and how to let it inflate and launch it. And, the three of us really did have fun watching it lift off, and then gazing at it for minutes until it flew out of sight and we couldn’t see it any more. Then I quickly got another one out and launched it as well.

My son and his family came over last Sunday, and I knew I just had to demonstrate these new toys for my grandsons. The photos below say it all.

So, now, back to my original quest: How to make sky lanterns.

Note: I’m gonna tell you how I ended up successfully making these homemade paper hot-air balloons. But, as with any pyro project, I learned some lessons the hard way, and I had some significant failures. I’ll note these as I go along in this hot paper tale.

Sky Lantern Autopsy

A little reverse engineering revealed:
Weight of a flying lantern	2.7 ounces
Thin bamboo hoop at bottom	45.75″ circumference, 14.56″ diameter
Weight of hoop	0.3 ounces (with a little paper and glue still hanging onto it)

Bamboo is about 1/16″ x 1/8″

X of thin wire tied to hoop

X of wire is “woven” through waxed cloth and paper “burner”

The burner is composed of a 2.5″ x 17″ piece of wax-impregnated cloth, folded in Z-fashion back on itself 5 times.

In between each Z-fold of the waxed cloth are five 2.25″ x 3″ pieces of thin, coarse-fiber paper, about the weight of 40# kraft paper.

(The cloth/paper burner smells “nice,” sort of like the scent of roses. Maybe the young Chinese lady who made this one was wearing some fragrant perfume.)

Note: I have also seen sky lantern burners, which resemble fiber-reinforced blocks of wax. I don’t know how they are made and have not tried to duplicate them.

The “bag” of the balloon is made up of white tissue paper. This paper has been treated with a fire retardant; it does not catch fire when touched by a flame. It just scorches a bit.

The tissue paper bag weighs 1.5 ounces.

There are four panels (called gores in the ballooning world) that make up the balloon, and they are glued together and to the bamboo hoop.

Here’s a sketch of one of the gores, with a bit added to the edges to allow for gluing.

I flew one of these fire-lanterns in my high-tech, windless wind-tunnel (actually my garage, emptied of any gas cans or other combustibles). I tethered the Chinese lantern to a weight with some very thin, light string as it burned. The fuel pack burned for 4.5 minutes.

I added 0.05-ounce pieces of wire, one at a time, to the bottom wire “X” of the balloon as it “flew,” and found it would carry 0.25 ounce of payload before starting to sag toward the ground garage floor. That 0.25 ounce, added to the paper-lantern’s original weight of 2.7 ounces, added up to a maximum flying weight of 2.95 ounces for a lantern with this internal volume.

It is the internal volume of a paper hot-air balloon, and the heated air it can contain as well as how much that air is heated, which determines its maximum carrying capacity.

Note: The information above is important. These flying lanterns are delicately balanced for flight, and they are just light enough to allow them to fly. If they were much heavier, they would not leave the ground. Due to some circumstances, which I describe below, my first balloon ended up weighing 3.9 ounces, and obviously would not have flown.

So, let’s make a paper sky lantern

I went up to my local Hallmark store and bought some nice tissue paper in different colors.

Some checking online produced some leads on products designed to flameproof paper. One company, Universal Fire-Shield (www.firechemicals.com), sells a product, Universal Paper Shield P-3000, designed to fireproof paper products. I ordered some. They sell a quart spray bottle for about $30, including shipping. This would be enough to treat about a dozen paper hot-air balloons.

I hung 4 pieces of the red tissue paper on a clothesline, and sprayed them with the Paper Shield until they were saturated. After they were dry, I tried to burn a little piece of the paper, and it only scorched like the original fire-lantern paper, but it would not burn.

Note: On my third attempt to make one of these paper lanterns, I decided to try to spray the untreated bottom half of the balloon after it was assembled, in order to skip the step described above. I hung it up, slightly inflated it with my heat-gun, and started spraying it. The tissue paper soon started to weaken, sag, and tear, ruining the balloon. Crud! Another lesson learned.

I decided that the process of hanging the panels like laundry works best. The upper corners of the sheets will be cut off when the gores are cut out, so I don’t spray those areas because they get weak when they are wet, and allow the clothespins to tear through the paper and sometimes that has the paper to tear loose from the string.

Warning: Paper Shield has an acid in it, and it will damage a concrete garage floor slightly. It’s best to have a plastic drop cloth under the clothesline to protect the floor. Don’t breathe its fumes or get it on your skin.

The red tissue will be the bottom of the paper hot-air balloon, which will be the only part that gets exposed to the flame. The top of the balloon will be blue paper, and it does not need to be treated.

I glued a piece of the red paper to a piece of the blue with thin stripes of Elmer’s, and I did that four times for the four panels, and let the panels dry.

Note: The Elmer’s glue tends to wet the tissue paper, bleeds through, and tries to stick to the other stuff around it. In an attempt to avoid this problem, I used hot glue when building my first balloon. This worked nicely during construction, but when I fired that baby up, the hot-glued seams at the top of the balloon let go completely. I did not think the internal temperature would get high enough to cause this problem. I was wrong. (My wife, Molly, told me later on that she wondered about me using the hot glue, and that she thought it would melt when the burner was lit. Oh, well.) The hot glue, which is significantly heavier than the dried Elmer’s, also contributed to the excess weight of the first model.

After gluing the red and blue sheets together and letting them dry, I cut the four panels out with scissors, using a kraft paper template that I made based on the sketch above. Folding the kraft paper in half lengthwise, and then every 6″ made the pattern transfer easy.

Then it was time to glue the lantern gores together to form the Thai-lantern’s “bag.” I laid one of the gores, unfolded and open, on the worktable with the inside up. (The outside of the gore is simply the side that I think looks best.) Then I laid a gore, outside up, on top of the first gore, weighed the two down, and glued the right sides together with a thin stripe of Elmer’s. The table had waxed paper on it so that any glue that seeps through wouldn’t stick to it.

I then folded the top gore’s loose side over on itself, so that half’s inside was facing up, inserted some waxed paper between the glued side and this loose side, and laid the third gore on top of that one. I glued those two loose edges together, inserted more waxed paper, folded the loose half of the third gore over, laid the fourth and final panel on top, and glued those loose edges.

Then the last step was to fold the loose half of the top, fourth gore, over on itself, and fold the loose half of the bottom, first gore over onto it, and glue the loose halves together. (This all sounds much more complicated than it actually is. Once you try it, it’ll all make sense.)

Then I pulled the glued edges up and off all the waxed papers, propped the panels apart from each other and from the table, and allowed the seams to dry.

Another Failure Note: On my first attempt to build one of these, I tried gluing the bag together with the panels inside out. I let the seams dry, and then I tried to turn the bag right side out, so that the seams would be hidden. This probably would have worked OK, but the fireproofed red tissue paper was somewhat brittle because of the fire-treatment, and as I tried to turn it inside out, it started to tear and crack at the bends and creases. I had to try to repair these tears with clear packing tape, which increased the lantern’s weight, and made it ugly, and not something to be proud of. I decided to simply allow the seams to be on the outside of the bag in future models, and avoid the “turning inside-out” step.

Making the sky lantern’s bamboo hoop

Home Depot had some 1″ diameter bamboo poles in their lawn and garden department. I bought one and carefully split it into thin strips. I took one of the strips and smoothed it with sandpaper and a razor knife until it was about the dimension of the original lantern’s bamboo. I only sanded the “interior” side of the bamboo because I did not want to weaken the smooth, exterior side of it. Then I glued it into a hoop with the same circumference of the original.

Another source of good bamboo strips is from a “Tiki-Torch” pole. These are often split to obtain bamboo strips for girandola frames, wheel frames, and the like. (Or you can steal some green bamboo from Harry Gilliam’s bamboo-infested front yard.)

Making the Sky Lantern Burner

I had some blue, industrial paper-towels, and I decided to melt some grocery-store canning-wax, and impregnate the towels with the wax in an attempt to duplicate the waxed fabric that I found in the original fire-lantern’s burner.

Warning: Canning (paraffin) wax is very flammable, and should only be melted over low heat in a double boiler. It should never be exposed to open flames or high heat.

I took a strip of this waxed paper towel, and burned it alongside a strip of the waxed material from the original lantern’s burner. Both samples burned identically and for the same amount of time.

I had some coarse, recycled kraft paper, and cut it into rectangles to match the original burner’s paper layers. Then I cut some strips of the waxed paper towel to match the original burner, and sandwiched 5 pieces of the kraft paper in between each layer of the waxed paper-towel.

Then I stacked the layers of the burner together, punched 4 holes through all the layers with an awl, and threaded two pieces of wire through the holes.

The ends of the wire were then wrapped around the bamboo hoop and twisted tightly to secure the ends. The hoop was then carefully glued into the end of the lantern’s tissue paper bag, and the glue was allowed to dry.

A simple alternative burner can be made by simply installing a plain X of wire on the bamboo hoop. Then strips of cotton-ball like material can be saturated with rubbing alcohol, draped over the center of the wire X, and ignited when launching the balloon. But keep in mind, you have to use this method right away; the alcohol fuel evaporates, and these have no “shelf life.”

All that remained, then, was the installation of the “FAA” aircraft identification numbers, and a flight in the “test chamber.”

This paper hot-air balloon’s final weight was 3.0 ounces. At about 50-degrees F in my garage, it was able to carry a payload of .55 ounces of the wire pieces before it started to sag toward the ground.

After this testing, some soot and moisture condensed on the inside of the lantern. I was able to allow it to dry out, attach a new burner, and fly it outdoors for real. It was about 40-degrees F outside on the evening that we flew it, and it really took off for the heavens very quickly.

Note: The flying lantern in on the right, Molly is on the left. The fact that Molly’s attire matched the balloon she was launching was entirely coincidental. That’s my story and I’m sticking to it.

Conclusions

This was a fun and educational project. I learned a lot about what to do and what not to do, when making one of these little hot-air balloons. This project was not as easy as it might look.

Based on my experience with flying the paper lanterns tethered in my garage, I think it would be fun to fly one outdoors in windless conditions, tethered by a short wire leader and a roll of light thread. It could be flown like a kite, reeled back in when the burner burns out, reloaded and flown again.

This project resulted in me having a high amount of respect for the folks overseas who turn these things out by the thousands, which fly successfully every time. I’m continually amazed by the low cost of a device like this, sold by Skylighter, compared with the time and materials I invested in producing a successful one.

It was fun to make these lanterns, and I enjoy knowing how to do it. If I had to come up with a bunch of ‘em for an event like a wedding, holiday, or memorial service, I sure wouldn’t be making them, though.

Happy Flying, and Stay Green,

Ned

Making a Firework Star Pattern Shell

A firework shell which bursts with a ring pattern, a smiley-face, or a star pattern can be a unique and creative addition to a fireworks display. Suddenly, after a procession of fairly typical full, spherical shell bursts, a simple ring of stars, or a display of four or five of them fired simultaneously, changes the focus of attention of the audience. “Hey, here’s something different,” they’ll think to themselves.

Pattern shells have some distinct advantages and disadvantages to their construction. They don’t use nearly the quantity of firework stars that a fully loaded shell would use, so if I have a few stars of a particular size and color, they might come in useful in a pattern shell. Patterns can be chosen to coincide with a particular theme in a show, with blue stars in a patriotic section, or pink hearts in a romantic interlude.

On the other hand, it will be hit-or-miss when it comes to the pattern’s orientation in the sky when the shell bursts. The smiley-face may display upside-down, or the ring may be seen on edge by a portion of the audience, looking more like a simple line in the sky. For this reason, most display designers choose to fire 4, 5, or 6 of the same or similar patterns at the same time. That will usually result in the audience in a particular location seeing at least 1 or 2 of them in the desired orientation.

If 6 ring-pattern shells of different colors are fired at once, the audience at one end of the field may see, say, the blue and red ones as true rings, and imagine all of them being the same shape.

Ring shells can use simple color stars, which leave no tail behind them, as in the photo above, or tailed stars can be employed, as below.

This Escher print, “Vuurwerk,” is on the cover of Pyrotechnica XI. It shows a pattern I would expect a ring shell of slow-burning, silver-tailed stars to display. It would have to be oriented so that the ring broke “flat” in order to display the “parasol” of stars just right.

A small rising comet tail produces the “handle” to the umbrella.

An advantage to using patterns such as rings, stars, squares or triangles is that they can break in many directions that still have them look correct, as long as they don’t break on-edge to the viewer. A smiley-face has to break in just the right direction to be recognizable.

The star-in-a-ring pattern shown below would look correct if it was rotated any number of degrees clockwise or counter-clockwise. It would also look fine if it was flipped 180 degrees front to back. The only way it would not show up well is if it broke on-edge to the viewer.

My friend, Mike B., made the heart-pattern shell shown below. While it did not break on-edge to the audience, unfortunately it did break almost upside-down. The fortunate thing about hearts is that they look good in almost any orientation, and the audience can make out what they are supposed to be representing.

I want to make a blue star-pattern shell. I don’t want to make my stars much smaller than 3/8-inch in diameter, so that they burn long enough to allow the pattern to show up. Additionally, ball shells break more symmetrically than cylinder shells. For these reasons, I’ve settled on assembling an 8-inch ball shell for this project. With 3/8-inch stars, a smaller shell simply wouldn’t allow the use of enough stars to create a nice star pattern.

The general construction techniques I’ll be using when assembling and finishing this shell were detailed in Fireworks Shells in 2-1/2 Days – Part 2, Part 3
and Part 4. I’ll be using 1/4-inch time-fuse in this shell, though, instead of a spolette. The use of time-fuse was explained in Really Nice 4″ Platic Ball Firework Shells.

The first thing I did was draw a pattern of the stars that would fit the inside diameter of one of my 8-inch shell casings, which has an ID of 7.25 inches. 360 degrees divided by 5 gave me 72 degrees between each of the points of the 5-pointed star, which I measured out with my protractor.

My 3/8-inch pumped stars actually end up being about 7/16-inch in diameter once they are primed, so I drew lines of that size star on my pattern. Precision in these initial planning stages, right through the actual construction of the shell, will result in a more precise star-pattern in the sky when the shell bursts.

I took a piece of tissue paper, cut a circle out of it about 1/2-inch larger in radius than my drawing above, and traced the star pattern onto it.

Then I made some blue stars. Firework Shells in 2-1/2 Days – Part 2 and Part 3 included instructions for making and priming pumped stars.

Although I didn’t need a large number of these stars, it was important that all the stars were consistent in size. For this reason I used a 3/8-inch star plate to make a pound of the Shimizu Blue star composition included in the table of formulas in 14 Great Cut Star Formulas.

Shimizu Blue Star Formula	Percentage	16-ounce batch	450-gram batch
Potassium Perchlorate	0.61	9.75 ounces	274.5 grams
Copper Carbonate	0.12	1.9 ounces	54 grams
Parlon	0.13	2.1 ounces	58.5 grams
Red Gum	0.09	1.45 ounces	40.5 grams
Dextrin	0.05	0.8 ounces	22.5 grams

I dampened this star composition with an additional 10% water, and pumped and dried the stars. I primed them with the black powder “meal prime” which is also in that star formula table cited above. I add an additional 5% of 200-mesh magnalium to the prime, which improves the ignition of perchlorate stars.

As I said above, the shell was constructed in the standard fashion, except for the details below.

Once I had the time-fuse and passfire-tube installed in the shell casing, I hot-glued a 1.5-inch wide tissue paper ring inside each hemisphere at the equator. These bands served the purpose of locking the shell’s contents into the hemispheres later on when I closed the shell.

Then I filled the fused hemisphere with black-powder-coated rice hulls, folded the tissue-paper band over onto the hulls, and hot-glued a tissue-paper disc onto the whole shebang to cover and seal it. As I loaded the hemi with the coated hulls, I packed them tightly one layer at a time to make sure the casing was solidly filled. I also filled the hemi slightly higher than the equator. This half of the shell held 29.4 ounces (825 grams) of the coated hulls.

Then I filled the un-fused hemi with coated rice hulls up to within about 3/8 inch of the rim. I made sure the rice hulls were tightly packed and very level. This filling was loosely capped off with the tissue paper disc which had the star-pattern traced on it.

Starting with the points of the star, blue stars were lightly hot-glued onto the tissue pattern. These stars only had a small dot of hot glue put on them where they touched the pattern. Just before the shell bursts, the tissue paper disintegrates and the stars are free to fly out in the star shape.

Then I filled in around the stars with more black-powder-coated hulls, tightly filling all the voids and bringing the level of the rice hulls slightly above the rim of the casing. This hemi actually took about 35 ounces (1000 grams) of the coated rice hulls, for a total of about 4 pounds (1800 grams) in the whole shell. This was all capped with another hot-glued disc of tissue paper.

Because the tissue paper rings and discs were glued to the shell casing hemispheres, it was easy to flip one of the hemis over onto the other and close the shell up, ready for pasting, lifting and leadering.

With the blue stars sandwiched between the layers of tissue paper, with the rice hulls really packed in tightly and the hemis overfilled and slowly tapped and brought together, the star pattern was held firmly in place.

I’ve developed a nifty trick for bringing the stuffed hemis together at the equator. I use 4 strap-clamps, available at Home Depot or stores which cater to woodworkers.

As the clamps are slowly tightened, tapping the shell with a solid, heavy rod brought the two halves together and solidly packed the contents. Then the joint was closed with strips of masking tape. This method is so much easier than “laying” on the shell while tapping it in order to close it.

Warning: I use a non-sparking, aluminum rod for tapping on the shell. But, the metal strap-clamp parts are not non-sparking. I’m working around relatively exposed black powder on rice hulls during this process. I’m very careful to avoid smacking the metal clamp ratchets, which could potentially cause sparks.

Then I pasted the shell, allowed it to dry, and lifted and leadered it. A small rising comet tail was attached to direct the viewer’s eye toward where the shell will break.

When I shot this shell, it did indeed break a bit on its “side” relative to the camera, as shown in the photo below. There were viewers down and to the left of the shell-burst, and they said that the star really looked nice, big, and symmetrical.

Oh, well, maybe I’ll get to see it next time.

Here’s a link to a video of the shell in action.

I enjoy making pattern shells. They offer a unique challenge in shell construction, and use less of the chemicals that go into stars. More black-powder-coated rice hulls are used than in a typical chrysanthemum or peony aerial shell, but these are the less expensive ingredients.

I think an audience enjoys the variety that these pattern shells bring to a display.

The next time I make a shell like the one in this project, I think I’ll add a red ring around the blue star pattern so the sky is filled a bit more when the shell bursts.

I’m working on my version of a way to at least have aerial shells burst with their equators level with the earth. This will allow rings, star patterns, etc, to display well for anyone underneath them. The method is one that I’ve heard about over the years, but have never seen, where a rope is attached to the bottom of the shell to produce drag on the shell’s way up. This keeps the shell oriented with its “bottom” down on the way up.

I plan on shortening the shell’s time fuse delay so that the shell bursts before apogee while it is still oriented correctly. I’ll keep you posted on the progress in this project.

Have fun and stay green,

Ned

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