Making and Testing High-Powered Black Powder
Take just 20 minutes to read this article, print it out, and use it to make this firework. You will be amazed at how well it will work as long as you follow the steps we give you here. Try this project today and see if you don't agree.
PGI grandmaster Ned Gorski teaches you how make and test high-powered black powder with red gum.
Materials Needed
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:
-
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.
-
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 (Skylighter #BK0043):
"Black powder - An intimate mixture of finely powdered potassium nitrate (75%), charcoal
(15%), and sulfur (10%). Commercial black powder may be granular or finely powdered. It
serves as a propellant and has a wide variety of uses. Black powder should not be
confused with smokeless powder, which is not a suitable substitute for black powder
(in fireworks)."
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. (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.
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, Skylighter Fireworks Tips #90.) 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, Skylighter Fireworks Tips #91.)
#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
Skylighter Fireworks Tips #92 and
#93.)
- Coating the BP onto rice hulls. (This method was detailed in
Skylighter
Fireworks Tips #92.)
- 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). (See the Nice
Shells in 2-1/2 Days - Part 2 article in Skylighter Fireworks Tips #92.) 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) 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.
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. (Skylighter Fireworks Tips #92 shows you how to make and use
a drying chamber.)
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 Fireworks Tips #93.)
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 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.
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
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