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
Whew! Lot of comments to read through. Entirely worth it though.
I have some inherited smoke compound sold by the other guy.
The friend who gave it to me had no joy with it, and neither did I.
!0 years later it’s still taking up space. Now I have a clear set of procedures for dealing with it. Thanks.
Re: Transporting bags of white powder; Now that AP is legal again, I recently crossed 2 county lines with a zip-lok full of it on the floor of the truck. Even with other rocket related clutter on board I was still worried about being pulled over. As well as numerous personal inconveniences, I’m sure it would’ve cost many taxpayer dollars proving the bag was what I said it was.
I would be greatly interested in more info about Red Gum BP.
I have made BP a time or three, but consider the larger granules I desire to be too fragile. Would RGBP be a better approach?
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Hi Harry,
I really enjoyed reading your Article. Even though I have not made smoke sence the early 1960s. I have a rule I use. Never assume anything.
I have allways screened or made sure each item is as fine as it needs to be.
I allways work slow and safe.
I allways mix well, and when I think its mixed good. I mix it more.
Back in the day I used a primer mix to light smoke and glue fuse in with.
I need to get back into smoke again. THANKS.
Rich.
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Many years ago while developing the Pyropak 2 component flash powders I learned the hard way that Cabosil TS-720 at a loading of 1% added to the oven dried oxidizers (strontium and potassium nitrates and potassium chlorate used in the smokes) enabled the storage of free flowing oxidizers for more than 10 years with absolute usability. The only thing that didn’t get Cabosil was the potassium nitrate used for glitters. Cabosil and glitters don’t get along very well, the presence of Cabosil decreases he performance of glitters substantially. I have used 2 Cabosils; M-5 for use in those compositions that require water binding, and TS-720 for the 2 component materials that were sold as powders. The TS-720 is water repellent to the point that the oxidizer treated with it could be poured into a glass of water, sink to the bottom encased in trapped air and resist dissolving for quite a long time.
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HEGilliam Reply:
October 7th, 2009 at 8:55 PM
Tom, That is good stuff to know. Thanks. M5 is what we carry. Do you feel that the flow-agent role of the two types was equal or different?
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Tom DeWille Reply:
October 8th, 2009 at 8:55 PM
I could not detect any significant difference in the flow properties. The water repellency was however a nice touch for making things flow 10 years later. The TS-720 Cabosil contains about 40 % silicon oil by weight, which causes the water to stay away. An interesting demo is to put your hands into a container of Cabosil TS-720 and scrub your hands together. Next put your hands into water or pour water over them and you stay dry whever the Cabosil is. I always used the TS-720 in salutes and the CuO/Al break charge I used in shells.
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HEGilliam Reply:
October 8th, 2009 at 11:24 PM
Thanks, again, Tom for the TS-720 tip. We ordered some today, and will make it available on the site, as soon as it comes in.
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Tom DeWille Reply:
October 9th, 2009 at 2:22 PM
The TS-720 Cabosil is great for use with Parlon, Nitrocellulose or other non aqueous binders. BTW the E-match kit oxidizer is oven dried and ground to -325. It is “flow treated” with TS-720 after being dried and then screened -200 twice to evenly distribute the Cabosil.
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HEGilliam Reply:
October 20th, 2009 at 11:24 AM
Tom, we got the TS-720 and packed it. It’s available now at skylighter.com, product number CH8051. Our ace Cab-O-Sil packer said that when he went to rinse his hands after packing it, they stayed dry! The water ran right off of them, yet they were dry, not greasy feeling. Spooked him.
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If you got some smoke from us and used it all up trying to get it to work, email me offline — not on this blog — and we’ll see what we can do to make you whole again.
–Harry
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That is some excellent insight, Harry. This seems highly applicable to many pyro projects.
I wonder what other great information that pyro log of yours has in it?
I think I’m inspired to go light something today.
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I am an aspiring newbie and have read that potassium chlorate is unsable and should never be ball milled, etc. does this apply only to the final mixed product or to the potassium chlorate itself?
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HEGilliam Reply:
October 7th, 2009 at 8:56 PM
To the final mixed product.
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Pat Reply:
October 8th, 2009 at 10:52 AM
Thanks for the information. is it ok to coffee grind potassium perchlorate too? I would think so as it is more stable than potassium chlorate.
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HEGilliam Reply:
October 8th, 2009 at 11:16 AM
Sure: potassium perchlorate, potassium chlorate, potassium nitrate, strontium nitrate, barium nitrate, barium chlorate, sodium nitrate–all can be milled this way.
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Pat Reply:
October 8th, 2009 at 11:39 AM
Thanks again.
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Berthold Schwarz Reply:
October 8th, 2009 at 10:35 PM
But only in your “oxidizer grinder” !!!!
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I purchased a blue smoke kit around May-June and had the same problem. I immediately thought the problem was due to not allowing enough time to bag mil the mix. Everything you read about mixing emphasizes both time and getting a very fine particle size. I still have most of the mix left over. I’ll give it another try using the recommendations in your article.
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Perfect example of the “Rule of Maintenance”. Keep with tried and true procedures for both safety and quality control procedures. No matter the quality of the ingredients when received, we find ourselves unable to take short-cuts around properly preparing the components each and everytime. No one can guarantee that raw materials will not become altered over time. It’s the curse of being a pyro… always mill and screen.
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smoke comp can be screened after the compounds are mixed.
hand screen the chemicals.
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So what are you going to do now with all those chunky kits you got sitting on the shelf? Start throwing two coffee mills in with each kit?
This reminds me of a problem I encountered several years ago. I had built a couple of girandolas which worked just fine. So I confidently headed off to a Crackerjacks shoot to do a hands-on girandola class. Same tubes, same nozzle clay, same bucket of fuel (a slowed down willow black powder), same tooling. Each person in the class built a little four driver girandola.
When we went to fire them, almost half of the drivers blew up! Fortunately the drivers were strong enough that most of the girandolas flew even with only two drivers left, but I was quite upset and embarassed. What had gone wrong?
When I got home, I pressed a bunch of drivers, weighing and recording at every step – empty tube, tube with nozzle, tube with fuel. Then I fired them all on my test stand and recorded the result. Looking over the data from about twenty tests a pattern emerged. The ones that blew up had a tiny amount more nozzle clay than the ones that performed correctly.
I thought about that and realized what was happening. The spindle used for forming the nozzles was tapered, and so a small amount more clay caused the nozzle to be thicker and go farther up the spindle, leaving a slightly smaller opening. This was enough to cause them to blow up.
Back to the bench, I pressed a nozzle with the right amount of clay and used a set of drills to figure out the nozzle diameter. It turned out to be a #17 twist bit was just right. I pressed a bunch more tests with varying amounts of clay, but before loading the comp I eased each nozzle with the #17 bit. Not one blew up. Problem solved, lesson learned. Now that is a standard part of my construction ritual.
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HEGilliam Reply:
October 7th, 2009 at 9:09 PM
NO NOTES! S kylighter does not officially condone pyrotechnic note taking.
People who take notes buy fewer chemicals. That is not good for America.
You should be able to see from Tom’s little case study that his detailed notes probably cost Skylighter several pounds each of charcoal and nitrate.
Tom, how do you expect this country to recover? Suppose everybody kept detailed notes? Think of the time wasted in taking notes. Sheeeeeyyzz..
NO NOTES!
NO NOTES!
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Yes, very helpful. It is way too easy to just mix like a pancake and wonder what went wrong.
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HEGilliam Reply:
October 7th, 2009 at 9:09 PM
Expensive, too.
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Harry, even though haven’t used your materials to the depth many of your other customers do, I could follow along with your description and processes. I believe many will fond this type of feddback quite valuable. Thanks for taking the time and effort to not only figure out the problem for your customers, but also for sharing not only the results, but the road that got you there. Keep up the good work.
And watch out for the ociffer.
Regards,
Russ
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Your detective work is a prime example of what my job has been for the better part of the last two decades. Unfortunately, my day job has nothing to do with pyrotechnics! Even more unfortunate is the state of the pyrotechnic industry and the hyper-focus of some misguided government agencies. In my line of work, a product engineer, your story ends somewhere near the start of a typical root cause analysis. Once we’ve identified the problem our focus shifts to internal and external (supplier) corrective actions. Once the corporation has to spend milions of $ on field actions or recals, even the bean counters cannot argue with the argument that commodity cost and value are in no way, shape or form equivalent. So, in the long run, engineering gets to pick a quality supplier who is almost never the lowest cost supplier. That’s where the correlation seems to end with the pyrotechnic industry. With all the government hassles it seems like even the quality suppliers (youse guys!) are having difficulties keeping their supplier base up to snuff. It seems to me that less Big Brother medeling would increase the supply base overall, eventually driving product quality standards upwards. The really sad comment is that in this wonderfull hobby we hold so dear, poor product quality can also have dire safety ramifications.
Sorry for the long rant, keep up the great work and just say no to more government!
Chris
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Years ago, when I was making fireworks that will NOT be discussed here, I uset the stainless steel bar mixer cup with a Osterizer. Milled anything to a fine powder in seconds, worked great–even for charcoal.
I ran two cups, oxidizers and reducing agents(fuels)–later, I added two more cups, for acids and alkalis. Came in rather handy doing biodiesel experiments.
Don’t make any fireworks these days–back in ’90, me and the ATF had a less than pleasant discussion,and subsequent “vacation”. Enough said.
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glad there are still a few old pyros around…
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So I got one of these kits with my turbo pyro I got this week as I was one of the first 50 to buy one. I have already mixed all of my smoke mix together and I do in fact have the said problem, I got a blue smoke mix by the way. So any solution to this when the two components have already been mixed ??
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HEGilliam Reply:
October 7th, 2009 at 9:12 PM
Try my recommendation to Claire, above, Robert.
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arnt all chemicals some what hyroscopic? small particles in suspension tend to have some browning movement and there is always some small electrical charges that causes attraction(clumping) in higher humidity climates, bet you dont have as many problems in dry climates
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HEGilliam Reply:
October 7th, 2009 at 9:16 PM
No, not all are hygroscopic and some will stay free-flowing more or less forever. Nor is all clumping caused by moisture. Make fireworks for even a little while and you will find that this issue of free-flowing, de-clumping, etc. is a constant in the process of firework making. Even Tom DeWille’s excellent tidbit below, nevertheless puts you into the process of protecting against moisture and making significant time investments in making that happen. It’s an inescapabale part of fireworking.
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Well done Harry! That’s some good scientific reporting there, and it was very helpful. I had been playing with the smoke mix I received in the turbo pyro kit, and I had some of those same problems. First, it wouldn’t lite, and then I upped the amount of KClO3 by 5 and 10% respectively. The added oxidizer helped the situation, but I still had the “sputtering” problem you briefly described. Like the previous poster, I added 1.0 wt.% Cab-O-sil to the KClO3, and that seemed to help a lot. Thanks to your expermentations, I will also now have to attempt the coffee grinder and increased screening method. Thanks so much for all the great communication of information; you’re doing a great job!
-Andrew
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Pete thanks for the education on particle size,,,There is one thing that bothers me,,(being a newbe in this art..I always hear about potassium chlorate being so unstable that in early days of powder making many explosions occurred when working with it…You being an expert knows what and whatnot to do when ballmilling a material .
I know enough to use non friction balls but it still scares me to alter pot chlorate..
Some mixtures say use a feather to mix components…Please educate me on the corredt way to handle said material…greatfully Andy
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HEGilliam Reply:
October 7th, 2009 at 6:19 PM
Andy, Chlorate is fine by itself. It will sit on your shelf contentedly thru freezing and hot weathers, etc. I’m not gonna attempt to explain chlorate chemistry. It’s use in smokes is *relatively* safe, particularly if you follow the instructions we give at http://www.skylighter.com/how-make-a-smoke-bomb.asp, and stick with small quantities.
But making smoke is not benign; a good friend of mine lost a very close friend of his to a smoke accident. But a very large quantity of smoke mix was involved.
Understand now..what I am recommending is not an “alteration” of the chlorate except in particle size, which is something you can do safely. But suppose you didn’t know that. Suppose you were wondering what would happen if you blade milled some.
Again, experiment. But do so with extremely small quantities. Take a pea-sized bit of potassium chlorate out to a rock or similar surface and whack it with a hammer. What happens? Suppose it heats up; will it explode? Put a blowtorch to it. What happens? Experiment, but do it in teeny, tiny doses.
Granted, you hear all sorts of things about pyro chemicals. But make sure that what you hear is really what happens. Do the work yourself to find out, so that you really KNOW.
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What do you do if you mixed up the whole batch, mixing mixed comp doesn’t appeal
to me
thanks
marc
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HEGilliam Reply:
October 7th, 2009 at 6:08 PM
Marc, read my reply to Claire above.
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I bought Pink, Yellow, Blue, and Orange smoke kits from you some time ago (still have the mixtures as they never worked). I was surprised to see this newsletter stating there was a problem. I had no idea what the trouble was and I figured I would not get any help if I called it in. My mistake. Thank you for sharing the discovery and solutions, that’s the way good science is done. My question now is this, “How can I fix the already mixed batches I bought?” I do not think I can simply grind it and sift it at this stage… I think now that I will just have to dispose of the mixtures. Good luck in your business!
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HEGilliam Reply:
October 7th, 2009 at 6:08 PM
Avi, Always let us know if you have a problem. See my note to Claire above on recovering the already mixed comp.
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I just want to say that I think your smoke bomb products are great. I actually bought a few kits and mixed them over a year ago and they still work. There is however, one thing I did with them that you did not recommend in your instructions……..that was to mix in a small amount of Zinsser Bulls Eye Amber Shellac, just enough to make it clump when some was compressed in my hand. This has helped hold the formulation together and seems to have assisted in keeping moisture out. Although I also keep moisture absording packets in with the smoke bombs.
A great product and a great article
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HEGilliam Reply:
October 7th, 2009 at 6:06 PM
Joe, did you notice any change in the smoke color/shade? What % did you add? Where I’m going is that people keep asking us for a way to make smoke stars (not box or pillbox stars, but a smoke pellet).
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Joe Reply:
October 7th, 2009 at 10:25 PM
I wish I could accurately answer those questions. I never compared the smoke bobms: loose powder vs that with shellac. Plus I somewhat packed the shellac formula inside the tube, which I may not do next time ( I think it burns more quickly and hotter with it packed — not the best for the possible burn off of smoke dye). But I got a great colored smoke. Looking back the few I burned as loose mix — I think the smoke was comparable.
As for percenatges; again, I did not measure out ingredients. I did add just enough to get the powderd smoke mix to stay clumped when squeezed slightly with your hand. i would assume that the lesser amount used may helpwith bettter colored smoke. Hope that helps some!
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the first problem should have been self explanatory
screen the comp before mixing.
secondly the same formula will not work the same with every dye color.
depending on the dyes and the dye color being used will dictate how many grams dye can be used in any particle color.
some colors are stronger than others thus less dye should be used or the smoke will not ignite.
increasing the oxidizer is not the proper solution.
the formula has to be adjusted to work with the dyes.
if the dye is to strong you would have to increase the oxidizer to make it ignite.
so one color smoke may require less dye to achieve the same effect.
increasing the oxidizer will only cause the smoke to burn faster.
more baking soda will slow and control the burn but will not help if you have more oxidizer added.
core burn smoke grains produce 3 times the volume as dead pack smoke.
adjust the dye in each color until the color is favorable.
do a open test burn with 100 grams.
adjust baking soda until the smoke comp smolders with very Little flare up if any at all.
the point is to make the smoke comp smolder not burn.
10 100 gram samples should be tested in each color.
adjust the dyes and when color is achieved work on the baking soda and oxidizers.
each color should have its own formula and not the same amount of dye in every color.
you will keep having problems with the smoke if your simple fix is just increasing the oxidizer.
that is not the proper way to salve the smoke problem.
the faster the smoke burns the less color will be achieved.
wider casings should be used in dead pack smoke or the burned smoke comp will filter the vaporized smoke dye,thus the color will fave further into the burn.
more oxidizer will get the comp to burn but you will sacrifice color doing so.
if you are using redy mixed kits than the customer cannot ajust the formula.
they have two ways to follow on kits,slow burn or fast burn.
formula has to be ajusted by the kit manufacture.
sincerely,
scott bowlan
pyrotechnics research/development co.
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I usually just store my powdered stuff in a baggy with one of those dehydrator bags or lozenges you get with medicine bottles and such. Place the baggy wherever you area going to keep it, put a small piece of cloth or plastic on top, ( big enuough to keep the dehydrator off of the chemical but not much more, to insure max air exposure) and seal the bag. This keeps the moisture content in the bag to a minimum and, at least for me, keeps clumping to a minimum as well.=)
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Oh by the way, the zinc stars, fabulous, i love the color, could i pump this comp into a small crossette star? I think it may burn to slow. Thanks!
Rich
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Harry,
That sounds like a very good idea. I have been mixing by grinding in a mortar and pestle.
i am going to buy 2 coffee grinders. Fast and easy!
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Harry Reply:
October 7th, 2009 at 9:50 PM
Tom, sitting around here somewhere is an accident report where the hand of a seemingly knowledgeable chemist (for Pete’s sake!) got blown to smithereens while “mixing” a pyro comp in a mortar in pestle. Grind only single chemicals in a mortar and pestle. DON’T GRIND OXIDIZERS AND FUELS TOGETHER IN ONE. Just do the chlorate-sulfur experiment above, so you can get a taste of the consequences.
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Thank you for the input, i purchase the red gum black powder kit and experienced the same problem, the potassium nitrate just wasn’t fine enough or so I think, I followed Mr. Gorski’s instructions on high quality red gum black powder. On the fourth, I ground in a coffe mill, the potassium, but I just couldn’t get the power I needed to lift a shell. So my next project is to build a ball mill, wish me luck!
Rich
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Harry Reply:
October 7th, 2009 at 9:46 PM
Rich, You’re on the right trail, podna. A ball mill is the simplest, easiest, and least hassle way to make good BP. RGBP does work, but not for everything. What it is is a stopgap measure that can help someone get some functional BP until a ball mill shows up in their Christmas stocking.
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just curious
if you have already mixed the smoke mix and chlorate together can you put that into a grinder, or it is just trash now?
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Harry Reply:
October 7th, 2009 at 9:44 PM
See my note to Claire on trying to recover it. No guarantees, but has worked for us in some cases.
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If your chemicals have absorbed moisture, that will throw off your weights also. Have you considered drying the chemicals and then re-weighing to see how much moisture was absorbed?
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Harry Reply:
October 7th, 2009 at 9:43 PM
No. Once I got the smoke working using the previously established chlorate to smoke ratio, I stopped. Also, we learned before that there is a range of ratios that works. For instance, in the smoke kits we have now, the chlorate is 27% of the total. The range of chlorate % might be 25-35% (that’s not actual. I’m just saying that might be a possible range). So even if the weight is off by a bit, the formula is clearly forgiving enough to accomodate it.
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I had the problem with the blue smoke mix, skylighter sent more oxidiser to solve the problem. Added the extra oxidiser and screened everything thru a fine kitchen screen. Would still not work, so I just thru the hole batch away. Learned not to buy smoke mix ever again.
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HEGilliam Reply:
October 7th, 2009 at 9:24 PM
Gary, send me an email with your name and zip code, and we’ll replace the whole kit. My apologies for the problem and for it taking so long for us to figure out.
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Thanks – That should fix the problem I have been having making my own smoke mixes . I was running them through double brass screens twice. Got the sputtering but worked OK.. Now I’ll use the grinder. The chlorate I always screened as it is very hygroscopic and we have that thing called humidity here. That is awesome to take the time and clue us in. Jamie in Florida
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Hi Harry,
I suppose this could be helpful and I know you are equally enthusiastic over the subject of fireworks as I am and can talk about it forever. That’s why I think you could have told us this solution in about 1/4 the time.
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Harry Reply:
October 7th, 2009 at 9:37 PM
True, true, but I was in a hurry. Shorter takes longer to write.
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I’ve noticed the importance of particle size myself, but my problem was at the opposite end of the scale. I mixed up a couple grams of some traditional powder to be used to produce a flash (NO report intended!), but both items had unusually small particle size. I burned it unconfined, thinking it would just flash and give out a puff of smoke. Thankfully, I used a bit of visco, instead of just my lighter! It underwent a DDT, and cracked the flagstone I had under it! Particle size matters a lot!
I think about that lesson every time I mix anything now. There’s a reason that recipes include particle size. YMMV.
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Harry Reply:
October 7th, 2009 at 9:37 PM
I had exactly the same experience and intention once. I had gotten some of that allegedly 2-micron mag in as a sample, and wanted to see how bright the flash would be. A 2 gram pile in the open blew the hell out of my picnic table. Glad I used visco, too. Taught me a lesson, I haven’t forgotten about testing new and untried stuff.
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Not to be a stickler, but you might want to say that as particle size goes up, the ratio of mass to surface area goes down. This means less surface to absorb heat and start the reaction we are lookin’ for.
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Harry Reply:
October 7th, 2009 at 9:33 PM
Rod,
Stickle on… thanks for the amplification.
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Harry,
Thanks for the information. It’s most useful.
Screening the mix occured to me, but didn’t consider it safe as my screens (Skylighter chinese rounds) have been used to screen sulfur and potassium nitrate both of which are incompatible with the potassium chlorate. Not knowing what is in the dye mix, I also felt it may be dangerous. I thoroughly clean the screens with a paintbrush after each use, is this adequate cleaning, or do I need a dedicated screen for potassium chlorate bearing compounds? I also have 2 coffee grinders, one for oxidizers and one for fuels(sulfur for one). Is the grinder used for potassium nitrate safe to use for the potassium chlorate after brushing clean?
Thanks, Scott Marshall
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Harry Reply:
October 7th, 2009 at 9:32 PM
Scott, I wouldn’t bother with a dedicated chlorate screen. In fact, if you clean ‘em well enough, you might not even need to bother with separate screens for oxidizers and fuels. My square wood-framed stainless screens have virtually no cracks and crevices. I scrub-brush ‘em with soap and water, and they’re clean as a whistle every time.
Look, Scott’s question is a good one. If you have never done this, try it: Put a little pea-sized pile of potassium chlorate on a cement block or rock. Then put about the same amount of sulfur on top of it. Then with a regular claw hammer, scrape the stuff back and forth across itself. Listen to and watch the snap, crackle and pop. Now, hit the pile with the hammer. Oh, and did I recommend ear plugs?
We all talk about chlorate-sulfur and dangers thereof. But it is good to get a little more intimate with this stuff, than just talking about it. To really get in your bones what happens, the nature of the explosion, the degree of friction, impact it takes, etc.
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Don’t most pyro’s mill their chemicals before mixing if they look like anything but a fine smooth powder. Unless we have a formula that calls for lower mesh size, we usually mill all of our powders (unless they’re metal based, then it’s pointless).
Good information to know though on the milling though for new pyro’s.
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Thanks for the laugh about getting pulled over and the helpful article. I am amazed time and time again at the importance of particle size and ratio making a huge difference in smoke mixtures. This article was very enlightening.
Nick
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Harry: Thanks for the update. I had problems with the smoke mix and got it to work OK by changing the mixture. I have a small rock tubler that I use to mill oxidizers and never thought to mill the comp mix since it is so floaty and messy. I did not know I could use a coffe grinder to mill chemicals safely.
Jeff
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This was very helpful. i did not have a problem whith my smoke mix but it is good to know for later use.
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Harry,
Great test and determination of the underlying problem. Chemistry is often the art of mixing things right! Thanks for the detailed explanation. Ken
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We have the same type problem with other chems. We ball mill our KNO3 to 10 microns and mix it with cab-o-sil. Leave it in a sealed plastic container for more than a month and you need to re-screen it cause it gets clumpy and changes the burning characteristics. The same is true for other chems.
It’s amazing the difference we found.
Pete
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HEGilliam Reply:
October 20th, 2009 at 11:14 AM
Pete, we recently added Cab-O-Sil TS-720 to Skylighter’s product line. It’s designed to keep the moisture out. See Tom DeWille’s note on it in the comments for this post.
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I cannot try this fix for my smoke, it is all mixed due to the problems with the Turbo Pyro kit I received. I am glad you found a solution, too bad it wasn’t in time to save my smoke
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Harry Reply:
October 7th, 2009 at 9:11 PM
See my reply to Claire, above.
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Verrrrrry interesting! Having gotten a blue smoke bonus with my recent Turbo Pyro kit, I’ll be sure to mill the components prior to mixing. I would also imagine that the smoke bombs should be used soon after assembly to prevent clumping in the canisters. I assume one or more of the chemicals are somewhat hygroscopic and the absorbed moisture contributes to the clumping.
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Harry Reply:
October 7th, 2009 at 9:10 PM
Well for sure the potassium chlorate is gonna absorb moisture. And I *think* at least some of the smoke mixes are hygroscopic as well. But I don’t know whether there would be a problem in longer term storage after a smoke can is made. Good experiment to do…
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Re: Smoke mixes after using up all my visco on the first batch of smoke mix I used a metal type sparkler to fuse them belive it or not this worked just something to think about.
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I really appreciate your thorough approach to your craft, Harry. I had some July 4th duds that bear revisiting in the light of this revelation!! Thanks for the insights!
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Harry Reply:
October 7th, 2009 at 7:57 PM
Claire,
If you have duds or any of the smoke, already mixed (oxidizer + smoke fuel), you may be able to make it work by doing this:
- first, mill up some more potassium chlorate til it’s super-fine
- weigh your mixed smoke, and add +10% more chlorate to that
- screen-mix the hell out of everything at least 3 times thru the finest screen you can find
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I had that very same problem but I thought it was just me
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Harry Reply:
October 7th, 2009 at 8:00 PM
Even if you had the problem, too, it was still you…
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After all of the above, how about adding some cabosil to preserve the non-clumping?
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Harry Reply:
October 7th, 2009 at 7:54 PM
Probly would work, Steve. I make my smokes and use ‘em pretty much real time, so have had no need to store them.
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Many thanks, Harry. I’ll give it a shot next decent-weather day we get.
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Great info, but are you shipping the coarser clumpy stuff still or is back to the previous finer grade components?
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Harry Reply:
October 7th, 2009 at 7:59 PM
It’s clumpy. FYI, non-clumping potassium chlorate is something I have not seen in all my years of being in this biz. And we have hundreds of pounds of colored smokes in stock, some of which are clumpy. But I assure you our true passion is to become the kings of non-clump. We will persist in pursuing the ultimate in free flowing powders!
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Greg Reply:
October 7th, 2009 at 8:38 PM
I make my own hp model rocket motors. We use AP, but it has the same clumping problem. The best way I have found to keep it from clumping after it has been broken apart is to store it with a bag of dissacint on top of the container. I currently use 5# bag from a sporting goods store. I keep it separated from the AP by setting it on a plate and the chemical inside of two plastic trash bags.
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I am restoring a WW2 British Armoure vehicle. It has two mounted smoke dischargers on it and I am trying to develop a smoke round to use at reenactments and displays.
Details: The Brits cut the barrel of a .303 Enfield rifle, threaded what’s left and screwed it to a 4″ Dia chamber. Using a blank round, the rifle fired a metal canister downrange and simultaniously ignited it. Smoke was a white/grey and used only to obscure vision. Not the infamous White Phosphorous used in the ’60s and later.
With the proper pares and tax stamp with BATF, we can recreate the smoke discharger itself, but the smoke rounds do not exist even in the collector’s markets.
For safety’s sake, a modern replacement can not weigh more than one pound, and have no metal in it. I thought to use a carboard tube cut to length and filled with a smoke mixture. A piece of waxed paper would be glued over the end that would ignite, while the other end would be a glued in wad of cardboard.
The .303 blank round would both loft the round downrange and ignite the round.
That is what I wan tto have happen. Now I ask the beginner’s questions… What do I mix that will work with this scheme?I would like to get a burn time of at least 3 minutes, although longer is better. WHat does the selected compound weigh? Can I get three minutes for the amount that would weigh under one pound?
Jsut as an FYI, at events where the smoke would be used, there is a fire responce force and safety helmets worn by participants.
If anyone has suggestions, I can provide email pics of the reference material.
Thanks,
Jim
15th Reconnaissance Regt Living History Assoc
a 501(c) (3) educational Non-Profit Charity
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