Making & Testing High-Powered Black Powder

Black powder (BP) is an almost ridiculously simple pyro ingredient. Mostly just three chemicals, blended together in simple ways, but producing wonderful results. Black powder exemplifies for me the endless learning, experimentation, and creativity that fireworking holds for us. If so much fun can be had with BP, imagine what else fireworks-making has in store for you.

In this article I’ll be writing about two basic skills:

1. How to make black powder using 4 basic methods, ranging from the use of only two simple screens, through the use of a star-roller, hydraulic press, and/or a ball-mill.

2. How to test various black powders to compare their power, and to determine how much to use when lifting a typical fireworks aerial shell.

I hope this article will be useful for both the novice fireworker, and for the most experienced one.

Have you ever taken the covering off of the bottom of an aerial shell and observed the black granules which are used as the shell’s “lift powder?”

Black powder is perhaps the most basic and useful of all fireworks ingredients. It is used to lift shells, comets, mines, Roman candle stars, and as a base-composition in some rockets and many other fireworks components and devices.

Here is the definition of black powder taken straight out of the The Illustrated Dictionary of Pyrotechnics (Skylighter #BK0043):

For the sake of this article, at least, let’s define high-quality BP as that black powder which will adequately serve the needs of the fireworker, and which comes close to, or exceeds, the quality and explosive power of commercially available black powder. Goex brand is a well-known, and often referred to, example of commercial powder.

First of all, didn’t we say, “Hey, I’d like to learn how to make fireworks”?

You can buy some types of black powder. There are two types available, sporting and blasting. The sporting grades of BP, made by Goex and others, are readily available from some gun and sporting goods shops, and some online sources. These are the “Fg, FFg, FFFg, FFFFg, ” etc. grades listed in the black powder grain size charts.

The blasting grade, “A” powders are most frequently used in fireworks. 2FA, 4FA, and Meal-D are the sizes we need the most. (See the article on black powder sizes and grades Size Does Matter in Skylighter Fireworks Tips #44.) They are available only to holders of a BATFE explosives license.

If you can find BP at your local gun shop, it usually retails for $16 – $24 per pound. Beginner shell makers can easily use more than 50 pounds of 2FA per year. That’s about $1,200 at retail! It doesn’t take long, buying commercial BP, before you start asking yourself, “Self, ain’t there a less expensive way?”

Even if one has the BATFE license to buy commercial 2FA in bulk (50 or 100 lbs at a time), the current price of it is $7-8 per pound.

So, economics, practicality, availability, and the pride of actual fireworks-making, all eventually make it inevitable that most pyro-hobbyists will make their own BP. And the good news is that it is Federally legal to make it yourself, without an ATF license. But, check your state and local laws first to make sure you can comply with them as well.

Many would argue that the very first, important step to learning the art of fireworking is tackling the skill of making high-quality black powder.

Typically, these are the key variables in making powerful, high-quality BP:

#1: The quality of the chemicals and the type of charcoal (wood species) that is used. Willow charcoal is often being referred to as the wood of choice for BP charcoal. I use spruce/pine as the wood that I turn into homemade charcoal. (This subject is discussed in the Making Charcoal article.) I’ll be comparing BP made with this pine charcoal, with that made with commercial airfloat charcoal.

#2: The method used to pulverize and intimately mix the ingredients. Screening through a fine-mesh screen or ball-milling can be employed. (This subject is thoroughly explored in Ball Milling 101.)

#3: How the mixed ingredients are consolidated and granulated.

#4: The size of the granules, especially with BP that is made into pucks that are broken up (corned).

I have played with several methods of making BP. Now I’m going to make black powder in four of those ways:

- Pressing BP pucks and breaking them up. (This method has been detailed in Fireworks Shells in 2-1/2 Days – Part 2 and Fireworks Shells in 2-1/2 Days – Part 3.)

- Coating the BP onto rice hulls. (This method was detailed in Fireworks Shells in 2-1/2 Days – Part 2.)

- Ball-milling the composition, wetting the BP with red-gum and alcohol, and granulating it through a 4 mesh screen.

- Simple screening of the chemicals through a 100 mesh screen, and using the red-gum/alcohol granulation method.

I ball mill four 20-ounce batches of mill-dust BP, two batches using pine charcoal, two more using commercial airfloat. Each batch has 15 ounces of potassium nitrate, 3 ounces of charcoal, and 2 ounces of sulfur. I run the ball mill for 2 hours for each batch. I end up with 40 ounces of pine charcoal mill-dust, and 40 ounces of commercial charcoal mill-dust.

(Mill-dust is the term that is used for BP as it comes straight out of the ball mill, before any granulation.)

I take 16 ounces of the pine charcoal mill-dust, add 1.6 ounces of water (10%) to it, and thoroughly incorporate the water into the powder with my gloved hands. Then I further incorporate the water with a screen colander. I press 1/8″ thick pucks with that powder. I have found that if I apply about 1600 psi of pressure on the pucks when I press them, that they are as solidly consolidated as they are going to get. I put the finished pucks into the drying chamber to dry.

I do the same with 16 ounces of the commercial charcoal mill-dust.

(I have found that it is quite easy to break the pucks up a bit by hand while they are still damp. This makes it easier to granulate them later on.)

Third Step
I take 16 ounces of the dry pine charcoal mill-dust, add 0.8 ounce of dextrin (+5%) to it, screen it to thoroughly incorporate it, and coat that BP onto 2.4 ounces of rice hulls in the star roller (7/1 ratio of BP to rice hulls). (See Firework Shells in 2-1/2 Days – Part 2.) I put the coated hulls on screens and into the dryer. Although puffed rice cereal can be used in this process, rice hulls make more durable grains.

I repeat the process with 16 ounces of the commercial charcoal mill-dust.

I take 8 ounces of the dry pine charcoal mill-dust, and dampen it with 1/3 cup of denatured alcohol (from Home Depot) which has 1/10 ounce of red-gum (about 1% of the mill-dust weight) dissolved in it. I slowly add enough additional alcohol to the mill dust, only as much as necessary, to end up with a nice, putty-like “dough ball.” Then I granulate that dough-ball through a 1/4″ (4 mesh) screen onto a kraft-paper lined tray for drying.

I repeat the process using commercial charcoal mill-dust.

Warning: Working with alcohol or any other solvent that puts a lot of fumes into the air, I do so outdoors so fumes cannot collect and be ignited, and I wear a mask-respirator to avoid breathing the fumes.

I simply take 15 oz. of potassium nitrate and screen it through a 100 mesh screen. If all of it won’t pass the screen, I mill it a bit in a small coffee grinder until it will pass the screen.

Warning: I never mill anything but individual chemicals in the coffee grinder. I use one coffee grinder only for oxidizers, and a different one for fuels. I thoroughly clean it after using it for one chemical.

Then I combine that 15 oz. of potassium nitrate with 3 oz. of pine airfloat charcoal and 2 oz. of sulfur, and pass them twice through the 100 mesh screen to thoroughly mix them.

This 20 oz. batch of BP chemicals is then wet with about 3/4 cup of the denatured alcohol which has 0.2 oz. of red-gum dissolved in it. More alcohol is added as needed and the putty is granulated as in Step 4 above.

I do the same for a similar batch using the commercial airfloat charcoal.

Many of you are now saying, “Aw, he’s never gonna get a useful BP with that simple screening method. It has to be ball-milled.” You just wait.

All of the powders produced above are left in the drying chamber until they are completely dry. (Skylighter’s project plans show you how to make and use a drying chamber.)

Once the powders have dried in the drying chamber for a day or two, I process them in various ways.

Processing black powder pucks (see how to granulate black powder pucks.)

With the pine charcoal pucks, I end up with 10.7 ounces of the 2FA, and 1.75 ounces of the 3FA. (In reality, commercial 2FA powder contains grains from 4 to 12 mesh, but my 2FA consists of only the coarser grains.)

With the commercial charcoal pucks, I ended up with 10.15 oz. of 2FA powder, and 2.05 ounces of 3FA.

Note: I don’t really like the process of pressing all these pucks, and then crushing and granulating them. It’s a painstaking, time consuming, and messy process. On the other hand, it is nice to end up with such hard, durable grains, which are practically indistinguishable from commercial black powders.

After dumping the BP coated rice hulls from the drying screens into a rectangular tub, I then simply screened them on my 12 mesh screen to sift out the fine BP grains and dust. There was not a whole lot of that, but I wanted to end up with just the coated hulls.

With the red gum/alcohol granulated powders, I dumped them from the drying screens and forced them through my 4 mesh screen to break up the larger clumps. Then I screened that powder on my 12 mesh screen to remove the fines and dust, ending up with nice, hard grains in the 4-12 mesh size.

Coating the rice hulls and processing the resulting grains is relatively easy, and the alcohol/red gum granulated powder is probably the easiest to produce. It is a bit more expensive to make, though, since the red gum powder and alcohol cost a little more than dextrin and plain water.

So, now I have my 10 homemade powders to compare with each other. I also have some German Wano 2FA powder (equivalent to Goex 2FA) which I screen and separate into 4-8 mesh and 8-12 mesh powders, as I did with the homemade powder made from pucks.

• Pine charcoal 2FA
• Commercial charcoal 2FA
• Pine charcoal 3FA
• Commercial charcoal 3FA
• Pine charcoal BP coated rice hulls
• Commercial charcoal BP coated rice hulls
• Pine charcoal, ball-milled BP, processed with alcohol and red-gum
• Commercial charcoal, ball-milled BP, processed with alcohol and red-gum
• Pine charcoal, simply screened BP, processed with alcohol and red-gum
• Commercial charcoal, simply screened BP, processed with alcohol and red-gum
• Wano 2FA
• Wano 3FA

Now I’d like to test these 12 BP’s and compare their relative performances.

So far, all of this is very interesting information, but, quantitatively, it does not tell me a whole lot that is useful for me in making fireworks.

I have some big questions I’d like answers to:

• To what extent does the type of charcoal affect the power of the BP?
• Consolidated and granulated using 4 different methods, how much variation in the BP’s power will result?
• How do these homemade BP’s compare in power with commercially produced powders? How can this be tested and quantified?
• How much should I use of one of these BP’s to lift an aerial shell?
• How do the various methods of production compare as far as expense and labor? Are some methods significantly easier than others for the manufacture of BP?

I have to admit that the process I’m about to describe is where my creative juices really start flowing in this hobby. Being curious about something, thinking about it, doing some experimenting, pondering the results, and coming to some conclusions that are useful in my future activities–that’s what this is all about for me.

We have quite a few variables in the above information when it comes to choosing how to make powerful BP and how to use it in our pyro projects.

I want to design an experiment to compare black powders which incorporate these different variables, in order to know how each of those variables affects the BP’s power, and to be able to determine which materials and techniques are preferable when making my BP.

I have my 12 different types of black powder sitting in front of me. Now I’ll test them in various amounts, lifting dummy shells, to compare their relative performances, and to find out exactly how much of each of them to use when lifting an actual fireworks shell.

In years past there has been a “game,” played at the Pyrotechnics Guild International’s annual convention, called “pyro-golf.” Folks brought samples of their prize black powders, and a fixed amount of each was used in a mortar to shoot golf balls into the air. The flights were timed, and the longest flight time would be declared the First Prize black powder. This is a good method for comparing the power of different powders.

Homemade powders could also be compared to commercial BP’s at the same time. Usually the homemade powders outperformed the commercial ones by quite a sizable margin.

There are other ways to compare black powder performances, but I like the golf ball test because it duplicates the real-life application of using black powder to lift aerial shells.

For testing my 12 BP’s, I’m going to use my version: “Pyro-Baseball.” With “Pyro-Baseball,” I use baseballs and a 3″ mortar to simulate the lifting of 3″ spherical fireworks shells. Baseballs are just the right size and weight. They save me the time, expense, and hassle of having to build actual dummy shells.

For my tests, I’m using a one-piece, HDPE (high-density polyethylene) “gun.” Whichever gun you use, it is a good idea to use the same mortar for all of the comparison shots. This will minimize variations from one test to another.

On page 140 of The Best of AFN II (BAFN II) are some charts showing recommended BP lift amounts for various types and sizes of shells. Table 1 indicates that, for lifting a 3″ ball shell, 0.6 oz. of FFg, or 0.75 oz. of 2FA would be appropriate amounts of commercial lift powder.

And, on Page 17 of the PGI’s Display Fireworks Operator Certification Study Guide, one can find a nifty table that shows the typical (desired) heights that various size fireworks shells ascend to before bursting. This table shows that a 3″ fireworks shell would rise to about 300 feet and then burst.

That’s good information to have. Using about 0.6 to 0.75 ounces of my Wano BP ought to send one of my baseballs up to about 300 feet. I can weigh that amount, drop it down into the bottom of a 3″ mortar, insert 4″ of visco into the fuse hole at the bottom, drop a baseball into the gun, and light ‘er up.

But, how do I know if the ball actually ascends to 300 feet before it peaks out (at apogee) and starts to descend? One simple physics equation is all that is necessary to figger that out. If you drop an object and time its descent to the ground, the distance the object has fallen, in feet, is given by the equation, Distance = 16 x time x time (16 x time squared), when the time is measured in seconds.

For example, if I fire my baseball, and start a stopwatch when its flight peaks out at apogee, and then stop the stopwatch when the ball hits the ground, I’ll be able to read the time it took the ball to fall to the ground from that peak. Let’s say that my stopwatch indicates a time-of-fall of 4.18 seconds.

To see how high the baseball was when it started to fall (at apogee), all I have to do is multiply 16 x 4.18 x 4.18 and I get a height of 279.55 feet. That’s pretty close to my desired 300 feet. So I know that using the amount of lift powder that I used, or maybe just a tad more, would be a good quantity of that BP to use in the future for this size and weight shell.

This is what I’ll be attempting to determine with each of the 12 experimental powders. Once I know those amounts for each powder, I’ll then be able to compare their relative powers with each other. I’ll tabulate that info and have some very useful results and conclusions. Just what I was looking for to begin with.

Note: An interesting relationship that I’ve noted during past tests is the amount of time a dummy shell takes to rise to apogee after being fired from the mortar, compared to the time it takes to fall to the ground. I’ve noted that it takes a spherical dummy shell approximately half the time to rise to apogee that it takes the shell to fall to the ground from apogee.

Another way of saying this is that, of the total flight time from launch of the dummy shell from the gun to it hitting the ground, one third of the flight time is spent rising to apogee, and two thirds of the time is spent falling to the ground from the apogee.

So, if I use various amounts of a lift powder and time the baseball’s flight from the apogee to the ground, adjusting the powder amounts as I go along, until that time of fall equals 4.33 seconds, then I’ll know exactly how much of that powder to use again to duplicate that height. 300′ = 16 x 4.33 x 4.33.

If I want a slightly higher flight for a shell, for example one with a long burning willow star shell, then I’d use a bit more powder.

So, I go out to my shoot site with my lovely assistant and all my testing materials: BP’s, scale, spoon, paper cups, notebook, pen, baseballs, mortars, visco, anvil-cutter (I never cut fuses with scissors, only with razor blade anvil-cutters), chairs, table, stopwatches, sunglasses, camera, re-bar, and duct tape.

No, she didn’t really try to catch the balls. She had to man (woman) one of the stopwatches instead.

The mortar was taped to a piece of rebar driven into the ground, angled away from us, and the ammunition was prepared. I had previously drilled a small fuse hole near the bottom of the mortar.

I had prepared some charts in advance to take notes for each powder test. The vertical axis represents the time of fall in seconds, and the horizontal axis represents ounces of black powder in 0.05 ounce increments. I drew a horizontal line at 4.33 seconds since that time of fall represents a height of 300 ft., which is what I’m shootin’ for.

Then, it was just a matter of starting to fire baseballs with measured amounts of one of the experimental BP’s, such as the one in the above chart: ball-milled, commercial charcoal, alcohol/red-gum granulated. We used two stopwatches, recording the total time of flight, and the time of fall from the apogee to the ground.

Judging the exact apex of the flight can be a bit tricky, since there is a second before the apogee where the flight up really slows down, and there is also a bit of time after the apogee before the ball really starts to pick up speed. But, we just did the best we could. It’s probably a bit more accurate to use a time that is 2/3 of the total flight time, from lift to landing.

Warning: After each baseball firing, there may be hot sparks remaining in the mortar. I am careful to wait a bit before reloading. Then I insert the visco fuse, drop the next portion of BP in, and then carefully drop the baseball in. I avoid getting any body part over the mouth of the gun when doing this, regardless of whether I know the fuse is lit.
A baseball fired at this speed could easily kill a person or remove a hand or arm.

I wanted to start with a small amount of the powder, gradually increasing it until I started to get flights that were a bit too high. I figured that would give me the spread of data which I could use to determine the right amount of powder for a 300’ high flight. The following is a listing of the amounts of this one particular powder that I used, and the resulting flight times that we recorded.

Ball milled, commercial charcoal, red-gum/alcohol granulation

Amount of BP	Time from apogee to ground	Total flight time
0.25 oz.	2.06 seconds	3.28 seconds
0.40 oz.	3.50 seconds	5.69 seconds
0.50 oz.	4.56 seconds	7.22 seconds
0.45 oz.	4.18 seconds	6.62 seconds

Below is a computer-generated graph of the data above.

When these coordinates were entered into the graph, a couple of things became obvious. There is a linear relationship between the amount of lift powder that is used, and the corresponding flight time.

This graphed line, if extended down to the bottom of the chart, points to an amount of BP which would not even get the ball out of the gun, about 0.05 ounce in this case.

That graphed line crosses the 4.33 seconds/300′ line, between 0.45 and 0.5 ounces of the BP.

Indeed, when the average time from apogee to the ground, is divided by the average total flight-time, the time from apogee to ground is about 2/3 of the total flight time from lift to landing.

With this powder, I’d use 0.5 oz. to reliably lift a 3″ ball to 300′.

We did this with each powder, firing baseballs about 40 times into the air.

Repeating the tests described above with each of the 12 BP’s, I was able to determine the optimum amount of each powder for lifting a baseball to 300′.

0.30 oz.	Milled pine charcoal, red gum/alcohol
0.35 oz.	Milled pine charcoal, pucks sized to 3FA
0.40 oz.	Milled pine charcoal, coated on rice hulls
0.45 oz.	Milled commercial charcoal, pucks sized to 3FA
0.50 oz.	Milled commercial charcoal, red-gum/alcohol or on rice hulls
0.55 oz.	Commercial Wano BP, 3FA
0.60 oz.	Commercial FFg recommendation from BAFN II chart
0.75 oz.	Commercial 2FA recommendation from BAFN II chart
0.75 oz.	Commercial Wano BP, 2FA
0.75 oz.	Milled commercial charcoal, pucks sized to 2FA
0.75 oz.	Milled pine charcoal, pucks sized to 2FA
0.75 oz.	Simply-screened, pine charcoal, red-gum/alcohol
0.90 oz.	Simply-screened, commercial airfloat charcoal, red-gum/alcohol

Note: It was almost difficult to use a small enough amount of the pine-charcoal/red-gum-alcohol powder. A third of an ounce is a mighty small amount of lift powder.

To what extent does the type of charcoal affect the quality of the resulting black powder?
Homemade pine charcoal produced powder that was marginally better than that produced with the commercial charcoal, but both can produce BP’s that far outperform commercial black powders.

How did the 4 methods of processing/granulating the BP’s compare when the resulting powders were tested? All three methods that employed ball-milling produced powders that were very comparable. The method that used simply-screened chemicals produced BP that, while not as powerful, was very functional in amounts comparable to commercial 2FA.

How does the size of the granulation of pressed pucks affect performance? For these 3″ dummy shells, the finer 3FA (8-12 mesh) granulation far outperformed the coarser 2FA (4-8 mesh) granulation.

How much lift powder should I use for a shell? The amounts in the chart above indicate how much of each type of powder to use for a 3″ ball shell. These amounts can be dialed in when manufacturing actual fireworks shells. In general, if I were to multiply the recommended amount of lift powder listed in the BAFN II table by 0.6 for the milled, pine charcoal BP’s, or by .75 for the milled, commercial charcoal BP’s, I’d arrive at a good starting amount of homemade lift powder.

How do the 3 methods of processing/granulating the homemade powders compare as far as difficulty and expense? The easiest powder to make is the screened red-gum/alcohol granulated BP, followed closely by the milled red-gum/alcohol BP, and then the BP on rice hulls. Pressing pucks and corning them is significantly more difficult and messy.

The red gum and alcohol make that method slightly more expensive in material cost than the other two methods. Milling requires an up front investment in a machine and milling media. Rice hulls are cheap, so using them does not make that method much more expensive than pressing the pucks. All of the methods of making homemade BP are much less expensive than purchasing commercial black powder.

For my purposes, either homemade or commercial charcoal produces completely satisfactory powder. I really like the ease of production, and the final resulting powder when the red-gum/alcohol method is employed to make BP, so I’ll probably use that method when making lift powder for aerial fireworks shells.

To me, the simply-screened, red-gum/alcohol method looks like the method-of-choice for simple, field-expedient, very functional black powder, and it can be produced without any complex or expensive machinery. This method is ideal for the beginning fireworker.

I think I’ll bring my bucket of baseballs and a couple of 3″ mortars to the next PGI convention, and whoever is interested can take to the field with me to go head-to-head with our prize black powders. May the best pyro win!

Enjoy and Stay Green,

Ned Gorski

Firework Shells in 2-1/2 Days – Part 3

“Give a person fireworks, and you make them happy for a day.
Teach a person how to make fireworks,
And you make them happy for a lifetime.”

This is a continuation of a series of articles that details the production of good, traditional, paper ball shells in a minimum timeframe, possibly at a three-day fireworks club event. I’m exploring the possibility of arriving at the meet with only a few chemicals, some other materials, some tools and equipment, but with no completed pyrotechnic compositions, and then producing these firework shells from scratch.

The original series of articles ran in 2007 in the Pyrotechnics Guild International’s Bulletins #152-155, and this is a somewhat revised and expanded re-issue of that series.

Part 1 – How to Make Charcoal, detailed the charcoal options for this project. It included the production of homemade charcoal to be used in the various components of the shells. The charcoal-making step of the process would occur at home prior to travelling to the pyro get-together.

The next article addressed ball milling materials, skills and techniques. (Ball milling will be put into immediate action once we arrive at the site and begin actual production of these shells in this part of the series.)

In Part 2, making black powder (BP) shell burst granules, black match, shell lift powder, and charcoal tailed stars were begun. Options for star rollers, drying chambers, hydraulic presses, star plates, and homemade shell casings were also discussed.

Today I want to check on how dry the items in the drying chamber are. I also want to granulate the BP pucks, prime the stars and finish drying them, make the spolette time fuses, assemble the shells and paste them in so that they can dry overnight.

I woke up this morning wondering how everything in the dryer was doing. I opened it up, took two stars out of the top screen, and tapped them together. I’ve learned that when they are pretty dry they produce a crisp, clacking sound like two stones being knocked together. The stars are doing just that.

I then took a couple of the stars out to a safe place and lit them one at a time with the propane torch, tossing them into the air when lit. They both ignited well and burned with nice spark trails, burning out just after hitting the ground. This is just how I want this star to burn.

Back in the drying chamber, under the star screens, I unearthed the screen with the BP pucks on it. I stacked the pucks up and weighed them. Yesterday, I started with 20 oz. of mill dust and added 2 oz. of water, so when the pucks are totally dry they ought to weigh 20 oz. again. They now weigh 20.2 oz, so they have just a bit to go. When the pucks are completely dry, they “clink” when they are tapped together, sounding like pieces of pottery or china. This morning they have a slightly duller sound.

I cut a 6″ piece of the black match off of the match frame and took it out into the field to light it. It was nice and stiff and it burned well and consistently.

And, from one of the bottom frames, I removed a very small handful of the burst granules. Putting them on a rock out in the field, I inserted a 6″ piece of the blackmatch and lit it. Great. A quick poof and the puffed rice cores disappeared in the flame. Good and dry.

Ah, life is good. Warning: I have a buddy who wanted to demonstrate how his BP rough powder burned. He made a pile of it and lit it with the torch. The whole backside of his arm got badly burned. Always test burn compositions and devices by installing a piece of fuse so that you can retreat before it all ignites.

Now I want to crush the black powder pucks and screen the granules into usable sizes. First, I put a puck in a little plastic baggie. Then I put the baggie on top of my 6×6 pounding post and whack it with a metal-headed meat-tenderizing hammer until the puck is busted into about 2FA (about 1/4 inch) size granules.

I do this with all the pucks, one at a time, and dump the BP into a 4 mesh sorting screen.

I sift all the granules out that will pass through that screen, and re-crush the granules that won’t pass through, until all the BP has passed through that screen and onto a sheet of kraft paper.

Then I pass that pile through an 8-mesh screen. The granules that won’t pass the 8-mesh, but have passed through the 4-mesh are dumped onto a paper plate, and are the 2FA lift powder, which will propel the finished shells into the air. (See black powder size charts.)

I then pass the remainder of the powder through a 12-mesh screen, and the powder that has passed through the 8-mesh but won’t pass the 12-mesh forms a pile of 3FA when dumped on a plate.

Doing the same thing with a 20-mesh screen kitchen colander separates the remaining powder into 4FA (same size as FG) and meal powder. What passes through the 20 mesh colander is Meal powder. What doesn’t pass through that colander is 4FA.

I wanted to end up with 12 oz. of 2FA for lifting the two 8″ firework shells, and I actually ended up with 14.3 oz. of it. So I weighed out and set aside 12 oz, and further crushed up the extra 2.3 oz. of the 2FA, along with the 2.5 oz. of 3FA, until it was all sorted into the 12 ounces of 2FA, 4.8 oz. of meal powder and 2.75 oz. of 4FA.

I measured 1 oz. of the meal powder onto a paper plate, and put it back into the dryer to use later in the making of the spolette time fuses. I also spread the 12 oz. of 2FA lift powder out on a screen and put it back in the dryer to insure that it is completely dry when I use it.

Lift Powder Note. I’ve compared black powder made this way with commercial BPs. In tests performed with baseballs shot out of a 3″ mortar, to produce a 300’ high flight (6.5 second flight time up and down, 4.33 seconds of fall from apogee to ground), the following powder amounts were needed:

0.35 oz. 3FA made from pine charcoal
0.45 oz. Commercial charcoal 3FA
0.55 oz. Wano Brand BP 3FA
0.75 oz. Pine charcoal 2FA
0.75 oz. Commercial charcoal 2FA
0.75 oz. Wano Brand BP 2FA

Testing with 6″ dummy shells, 2 lb.-6 oz. shell weight, using 3 oz. of lift, produced the following results:

Willow charcoal 2FA	11.06 seconds flight
Pine charcoal 2FA	11.65 seconds flight
Commercial BP 2FA	12.46 seconds flight
Commercial BP 3FA	13.28 seconds flight

So, I’m confident that making BP with the SPF (spruce/pine/fir) homemade charcoal, or with commercial charcoal, produces results that are comparable with willow charcoal and commercial powders.

Note: In a future article, I’ll be detailing various black powder production methods, and procedures for testing the various powders and comparing them with each other. Stay tuned.

Now I want to prime one end of each star. With the black powder break charge that I’m using in these shells, these stars will probably all light without priming. But I like to be on the safe side. The primed end also adds a bit to the break, and speeds up flame propagation on the star.

I mix 0.2 oz. of dextrin with the 3.8 oz. of BP meal and wet it with some water to make a prime-slurry in a plastic tub. Using a little paint brush, or at other times dipping the end of the star into the slurry, I wet one end of each star with the prime-slurry. Then I press the wet end into the 4FA to form a rough, granular-primed end on each star. It took me an hour to prime all the stars and put them back in the dryer.

Note: The method of priming stars outlined above is not my favorite or standard method. I employed it in this project to speed the process up, since the stars can be primed, dried, and assembled in the shells the same day.

My regular method of priming these 113.9 ounces of stars would be as follows:

• Make a “scratch-mix,” BP prime by screening together:

  Component	Weight
  Potassium Nitrate	24.9 oz.
  Airfloat Charcoal	4.9 oz.
  Dextrin	1.7 oz.
  Sulfur	3.5 oz.
  Total Weight	35 oz.

  (This is a 15/3/2/1 ratio of the ingredients)

  (Referring back to Part 2 of this series, 21 ounces of BP mill-dust, including dextrin, was set aside from the second ball-mill batch. This could be used as part of the above prime. To this 21 ounces, 9.9 ounces of potassium nitrate, 1.9 ounces of airfloat charcoal, 1.5 ounces of sulfur, and 0.7 ounces of dextrin, would be added and screened into the mill-dust to make the prime.)

• Divide the stars into five lots, about 23 ounces each lot
• Divide the prime into five batches, 7 ounces per batch
• Put one lot of the stars into the star roller

  

  Small Star Roller

  (This is assuming that I’d be using my smaller, stainless-steel pot roller. If I was using my larger, cement mixer roller, I would experiment with priming 2 or 3 of the 23 ounce lots or even all of the stars at one time.)

• Out of one of the batches of prime, take 1/4 cup of the prime powder, place it in a paper cup, and add 2 tablespoons of water to it, stirring to mix up a thin prime “slurry.”

• Start the star roller with the 23 ounces of stars in it, and dump the slurry onto the rolling stars, using gloved hands to thoroughly coat the stars.

• Slowly add the remaining dry prime powder out of the 7 ounce batch, 1/4 cup at a time, working the stars with the gloved hand to keep them separated, and spraying with water as necessary, until all the prime has been taken up by the stars and they have a nice, solid, “crusty” looking coating of prime on them.

• Dump that batch of stars onto a drying screen
• Prime the remaining 4 lots of stars in the same manner

The disadvantage of this method, from the viewpoint of this project, is that it takes 24 hours for the stars to completely dry. If I had that extra day, I would employ this method for the star priming.

10:00 am – 12 noon. Take a little break and let the stars and spolette meal powder dry completely.

12 noon – 12:30 pm, Make spolettes.

I’m making spolette time fuses for these shells, rather than using commercial time fuse, because I want to make the shell completely from scratch, using only a couple of chemicals.

Note: From Traditional Cylinder Shell Construction, Part I, Pyrotechnica IX, by A Fulcanelli, “The spolette is the oldest and most versatile type of shell fuse. It consists of a small-bored and relatively thick-walled tube, charged partially with pure commercial meal powder.”

Pyrotechnica IX and XI contain the complete “Fulcanelli” series on this type of shell construction, and those of us who are familiar with this resource can’t recommend it highly enough.

I have found that my homemade BP meal powder, such as that which was derived from the corned pucks above, works very well in spolettes.

My spolette tubes, which I’ve had for awhile, are 3/8″ ID, 1/16″ wall, 2.25″ long, parallel wound tubes. (Skylighter sells some nice spolette tubes which are just a bit larger in OD.) I want 4 seconds of timing for the 8″ shells, and based on Fulcanelli’s figures, that ought to be about 1-3/8″ of solid powder, plus 1/16″ at each end for scratching back, for a total of 1-1/2.”

First, I cover one end of a tube with masking tape and ram it with that amount of powder, using my 3/8″ solid aluminum rod rammer, a little aluminum puck ramming base, my rawhide mallet and my 6×6 pounding post.

I pound 1/8 teaspoon at a time, which produces 3/16″ increments, until I have a solid powder column in the tube 1.5″ long. Then I scratch both ends of the solid powder core with an awl to a depth of 1/16,” and attach a piece of visco fuse with masking tape.

Burning that spolette in a safe location, and timing it with my stopwatch, reveals a time of 3.2 seconds with this black powder. I recalculate the length of the powder core I’ll need for 4 seconds, and arrive at 1-3/4,” plus 1/16″ inch on both ends for scratching back.

I make a spolette with 1-7/8″ of powder, scratch the ends, burn it and time it, and get 4.1 seconds. Perfect. I then pound two spolettes with the 1-7/8″ powder column (this takes 0.2 oz. of powder for each spolette) and scratch the inside powder with the awl. Note that the finished spolette has powder flush with one end of the tube and covered with masking tape, and leaves 3/8″ of the tube still open and not filled with powder.

Note: A friend recently gave me a nice tool set for making spolettes. It is similar to what Rich Wolter makes (wolterpyrotools.com) and may have been made by him. It has been machined to work with the size tubes I am currently using. The grooves on the shaft of the ram, 1/4″ apart, come in handy for gauging the height/timing of the powder column which has been rammed.

I’m using commercially produced, Chinese, strawboard hemispheres for these shells.

My spolette has a 1/2 inch outer diameter. So, using my half inch steel punch, I knock a hole in two of the hemis, using my rawhide mallet and the 6×6 pounding post.

Note: Awhile back I purchased an inexpensive set of gasket punches at http://harborfreight.com/. These punches come in handy for punching holes in stuff like the shell casing above.

I then hot-glue the spolettes in the two hemis, forming nice fillets of glue on both the inside and the outside, allowing 1″ of the flush end of the spolette to stick out on the outside.

I removed the masking tape to insert the spolette. Now I cover the outside end of the spolette with tape again, making a little “flag” with the tape for orientation during the pasting process.

On the inside of the hemi, I take a 5″ x 5″ piece of 40# kraft paper and make a passfire tube with three turns of the paper rolled up on a half-inch dowel. Then I hot-glue the tube over the spolette tube. I’ve enlarged the dowel just a bit with some masking tape to make sure the passfire tube will fit over the spolette tube.

Sighting across the plane of the hemi equator, I use scissors to clip the passfire tube off flush with that plane. I then insert two pieces of black match, making sure they fit down into the spolette tube and are pressed against the scratched column of black powder, and sticking out of the passfire tube about 1/2.” I then tie the end of the passfire tube with a clove hitch, and use my awl to punch a vent into the passfire tube below the string.

Note: here’s where you can see one way to tie a clove hitch knot.

The clove hitch is the most-used and versatile knot employed in fireworking, and there are several ways to tie one. At one time, I spent some time sittin’ in my LaZBoy chair, with a piece of string, and practicing the various ways of tying a clove hitch until they became second nature.

I remove my stars from the dryer and try to pry the prime off of one of them. The prime is very hard and dry, and pulls off some of the star along with it. This indicates it is thoroughly dry and fully adhered.

I like to hot-glue my stars into the hemis with a small stripe of glue on each star, applied to the end opposite the primed end, beginning with the stars at the equator. I use four rings of 4″ PVC pipe as stands for the hemis during this process.

I glue the stars in about 1/8″ below the equator because the angle of the hemi brings the inside edge of the stars just above the equatorial plane, where they will mesh with the stars in the other hemi.

I then fill the rest of the hemis with stars, lightly gluing each one in.

In a few cases I chip off edges of stars with a knife to allow a spot to be filled with another star. (I do this outdoors in a safe location.) Each hemi holds about 72 stars, for 144 stars per shell.

After filling all 4 hemis, I have 215 stars left over, enough for another shell and some rising tails. (I could have made 2/3 of the stars in the original batch if I wanted to avoid having these extra stars to dispose of. Maybe I can rustle up some more BP and make a mine or two.)

I remove the burst powder from the dryer, line the stars in each hemi with tissue paper, and fill the tissue with the burst charge, clipping off the extra tissue paper with scissors. I allow the burst to project above the hemi just a bit. When I mate the two halves of the shell, I want to have to work a bit at doing so, so that, once they are mated, the shell contents are tightly packed in place.

Note: At some point, if you’re like me, you’ll say, “Heck, I don’t need to keep that old burst powder separate from the stars with that tissue paper. I’ll just dump the burst in on top of the stars and work it into the voids.” Yep, that’s what you’ll say, and that’s what you’ll try, and then, after you close the shell and continue to work on it, the burst will migrate further in between the stars, and the burst and stars will start to loosen up, and the contents of your shell will start to rattle around, and your shell burst will look asymmetrical and ragged, or else the shell will flowerpot on lift (break in the mortar when it is fired).

Then you’ll say to yourself, “Well, that was a good experiment and a valuable lesson learned.”

And, you’ll go back to using the tissue paper. Yesiree.

I then close each hemi with a circle of tissue paper, hot-glued to the equatorial ring of stars. This paper disc is easily made by taking a square of tissue paper slightly larger than the casing, folding it in half, then quarter, then eighth, etc, and then clipping the folded paper off to the right length, as shown.

Note: There has been quite a bit of conversation in pyro-circles about the safety of using hot-glue when fireworking. The heat of the glue is not a problem, being well below the ignition temperature of the commonly used compositions. The problem can arise, if and when the hot-glue gun malfunctions, and possibly emits sparks. Some pyros allow their guns to heat up, and then unplug them before gluing.

The general consensus is that the most important safety precaution when using a hot-glue gun is to keep the gun on its stand, or sitting in a “garage,” like a length of PVC pipe, when it’s not in use.

That also keeps its innards from getting gummed up with excess glue, a common cause of malfunction. If one lays the gun down on its side while it’s being used, the excess glue ends up all over it, and some ends up seeping into its bowels. My guns, when used this way are a mess. But when a gun is stored during use with the tip pointing down, either on its stand or sitting in a “garage,” the excess glue just drips off the tip. The glue stays new, shiny as the day it was born, and not all gummed up inside.

It’s also probably a good idea to avoid using those “dollar-store,” el-cheapo hot-glue guns.

Now it’s time to mate the hemis by flipping one of them over quickly and onto the other one, and then setting them tightly against each other by applying pressure with my hand and lightly tapping with my rawhide mallet. Then the hemis are secured together with high-adhesion masking tape.

I know what you’re asking, “Does this guy ever take a break or eat?”

I am determined to get these shells pasted-in and in the dryer before dark and the beginning of the evening’s festivities. And, no, nobody ever accused me of passing up on a meal.

“Pasting” a shell is the process of applying layers of reinforcing paper onto the exterior of the assembled shell hemispheres.

I mix up some wheat paste (the good stuff from pyrosupplies.com) in my blender until it is about the consistency of yogurt. Wheat paste is the old-fashioned wallpaper paste. I know, I know, how would you fellas, who are reading this, know what the consistency of yogurt is? Real men don’t eat yogurt. Go buy a little tub of it and check it out. I like strawberry. (No, you cannot paste your shell in with strawberry yogurt!). But I digress.

I like to paste 8″ shells with 1″ x 9″ strips of 40# virgin kraft paper. I have an 18″ wide roll of this paper in a dispenser. I tear off twelve 9″ long sheets, and do this four times, making 4 stacks of 12 sheets. I am going to use one stack of 12 sheets for each application.

I can only cut through 6 layers of the paper with my sharp knife (which I keep really sharpened). So I paste up 6 pieces of the paper on my cutting board. I apply paste to the cutting board; paste both sides of the first sheet and then lay down the rest of the sheets, feathering them as I go, and pasting only the top side of those 5 sheets.

Now, after marking my 1″ widths with my marking screw-board (there are screws every 2,” and I eyeball the intermediate cut marks), I cut the sheets into 1″ wide strips.

Now I pick up one stack of 6 strips at a time, and lay down 9 of the stacks on top of each other, feathering the ends as I go. Then I roll them up into a little roll.

I do this twice for each cutting board batch, and there are two of these batches for the total of 12 sheets, so I end up with 4 of the little rolls of strips.

By the way, this paper and this method require no “breaking” of the paper. (Breaking paper, as described by Fulcanelli, entails crumpling it up to incorporate the paste and break the grain of the paper.)

The first thing I like to do is to brush some paste onto the shell and smear it around with my hands, preparing the shell casing so the pasted strips of paper will really adhere to it.

I like to apply the strips in the “9 axis system” described by Jim Widmann in his PGI Bulletin article, Bulletin #123, March/April 2001. This system uses the 3 main axes, x/y/z, as well as the 6 intermediate axes, which are rotated 45 degrees from each of the main ones. The little masking tape flag on the spolette is used to keep track of the axes as the pasting progresses.

Don’t worry if this is not immediately clear. I lay awake for a bit on a couple of nights visualizing all of this until the light went on inside my head. The purpose of this system is to rotate the “poles” of the layers of paper, so that the final, consolidated wrap of paper has a consistent thickness and strength.

As seen in the above photos, there are open spaces left at the north and south “poles” left after applying the 9″ strips, and these poles are covered with torn strips of paper.

Each roll of strips is sufficient for one axis application, which produces 2 layers of paper on the shell since the strips are lapped by half over each other as they are applied. So, the 4 rolls are good for the first 4 axes, or 8 layers of paper.

As I apply successive layers of the paper strips, I keep the shell nice and wet with the paste, by applying a bit with the paint brush and smearing it around with my hands.

After applying the first 12 sheets/4 rolls/4 axes/8 layers of paper to the first shell, I place it in the drying chamber, with the shell resting on two strips of wood which lie across one of the drying screens. (The shells may be too heavy to rest directly on the screen, and I don’t want them sticking to it.)

While the first shell is drying a bit, I apply the first 8 layers to the second shell. The first shell has taken about an hour to paste, and it dries for an hour while I’m pasting the second shell. Once this is accomplished, I switch the shells in the dryer and make the second 8-layer application to the first shell, then switch them again, and apply the final 8 layers to the second shell. Now I have 16 layers of pasted paper on each shell.

Sometimes, if I’m getting fancy, I apply a few drops of red or green food coloring on the shell as I’m applying the last layers of pasted paper. This results in uniquely colored shells.

Note: One alternative method for pasting the shells is to use gummed, kraft-paper tape, and a tape wetting/dispensing machine. The tape would be applied to the shells in similar lengths and fashion as the pasted paper above. I like to use 1-1/4″ wide, 35-40# tape on 8″ shells.

The next and final chapter in this series will detail Sunday’s lifting and leadering of the two shells. Then we can take them out to the field and put ‘em up into the air!

Till then, Stay Green,

Ned