Making and 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.

Introduction

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.

What is Black Powder (BP)?

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 Used As Shell 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 (BK0043):

So, What is "High-Quality" Black Powder?

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.


Goex Brand Black Powder

Well, Can’t I Just Buy the Black Powder I Need?

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. 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.

What Affects the Quality of Homemade 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).

Four Methods of Making Black Powder

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 "Tiger Willow Shells in 2-1/2 Days, Day 1" and "Tiger Willow Shells in 2-1/2 Days, Day 2".)

- Coating the BP onto rice hulls.

- 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.

First Step

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.)

Second Step

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.)

Black Powder Pucks, Pressed and Crumbled

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). 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.

Plain and Black Powder Coated Rice Hulls

Fourth Step

I take 8 ounces of the dry pine charcoal mill-dust, and dampen it with 1/3 cup of denatured alcohol (from Home Depot) in which I previously dissolved 1/10 ounce of red gum (about 1% of the mill-dust weight). 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.


Black Powder with Red Gum and Alcohol, Granulated
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.

Fifth Step

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.

Granulating and Sizing the Black Powders

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 in "Tiger Willow Shells in 2-1/2 Days, Day 2".)

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.

Processing black powder coated rice hulls

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.

Processing red-gum black powder

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.


Black Powder with Red-Gum and Alcohol, Granulated

Some Observations

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 and alcohol cost a little more than dextrin and plain water.

Results

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.

The Big Experiment

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.

Testing the Black Powders.

In years past there has been a "game," played at the PGI 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.


3" Mortar Loaded and Ready for "Bear"
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.


Timing the Fall of a Dummy Shell
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.

Pyro-Baseball Testing of Black Powders

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.

My Lovely Assistant, Ready to Take the Field, and the Ammo
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.


One of My Hand-Plotted Graphs
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.


Baseballs After Being Fired From the Mortar
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.


Ball-Milled, Commercial Charcoal BP, Red-Gum/Alcohol Granulation
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.

Results

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.

Answers

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.

Final Conclusion

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