CIA Black Powder Déjà Vu Once Again
Chemicals needed to make CIA black powder:
- Potassium Nitrate
Get your potassium nitrate, sulfur and charcoal in our Black Powder Chemicals Kit and save 20%!
This article originally appear in Best of AFN VII:
It's happened before, it will happen again I'm sure, and it happened once more last Monday. There was that inevitable phone call: "Hey man, yah, listen: I keep hearing about this so-called CIA black powder. But when I Google that I don't get any hits. So what's this CIA powder all about?"
It's been in excess of 20 years since we published anything about this particular method of making black powder so it's reasonable to assume there a body of folks who really don't know what it's all about. Perhaps with today's advanced workers using ball mills and other techniques to make the propellant, the so-called CIA method is no more than a curiosity.
On the other hand, it is an interesting procedure and does have the capability of producing a propellant powder that works. And it is a chance to convert that crappy, crystalline, hard-as-a-rock potassium nitrate into something useful.
Following is the original 1984 "Revisited" AFN article by Don Haarmann that explains the procedure, then a little insight from Ken Kosanke, and surprising follow up by Randy Peck that will make you ask, "Why didn't I think of that?"
CIA BLACK POWDER REVISITED
By Donald J Haarmann
With the sale of the booklet CIA Field Expedient Preparation of Black Powders many pyros rushed out to their local stores and purchased potato ricers, and isopropyl alcohol by the gallon. Soon after the little woman had left the house, they proceeded to produce the damnedest mess seen in a pyro's kitchen in quite a while, along with black powder of varying qualities.
However, all is not lost as H.W. Voigt and D.S. Downs at the Seventh International Pyrotechnics Seminar presented a paper dealing with black powder igniter pills produced in part with black powder obtained using a modification of CIA method. This paper contained several interesting revelations, the first being an early attempt at producing black powder using a "salting out" method (aka, the precipitation method) by one Edward Greene (USP 160,053) of New York, January 25, 1875) Greene's method consisted of mixing the sulfur and charcoal in a saturated solution of potassium nitrate, as close to the boiling point of water as practical, and then removing the excess water by connecting the mixing vessel to a vacuum, with constant stirring. (The boiling point of water at 760mm of mercury (atmospheric pressure) is 100°C. However, if the pressure is lowered to say 100mm of mercury, the boiling point of water is lowered to only 52°C. Therefore, a great deal of water can be removed rapidly (flash evaporation) resulting in the "salting out" of the potassium nitrate.) No doubt due to the difficulties in producing the required vacuum, and for other more technical reasons, this method was never used.
The second revelation is the fact that although generally credited to the CIA, the production of black powder through the use of alcohol as a dehydrating agent was developed at Frankford Arsenal, by T.J. Hennessy. ("Field Expedient Preparation of Black Powders", Frankford Arsenal memorandum Report M67-16-1, Feb. 1967.) The method they use differed from the "CIA" process in in a number of important ways: Whereas the CIA method added alcohol to a a mixture of sulfur, charcoal, and potassium nitrate in hot water, Voigt and Downs method mixes the sulfur and activated carbon black (in place of charcoal) in alcohol, along with two other ingredients, and then to the mixture is added the potassium nitrate dissolved in hot water.
The details provided by them are as follows:
45 grams of potassium nitrate was dissolved in 45 ml. of water at about 75°C. 2.5 grams of potassium nitrate were added to compensate for loss in the filtrate. (A loss of less than 6% as compared with a loss of over 18% for the CIA method.)
6.24 grams of commercial flowers of sulfur (most pyros do NOT use flowers of sulfur due to the possibility of its containing free acid, so normal pyro grade sulfur should be used) and 8.76 grams of activated carbon black (not lampblack) were suspended with vigorous agitation in a solution of 0.135 gram of polyvinyl pyrrolidone (a dispersing agent - try a wetting sulfur some time!) and 0.6 grams of mercaptan terminated polyacrylic liquid polymer (BF Goodrich Co. Hycar MIA - a binding agent, don't worry, you can leave it out) in 135 ml. of 95% ethanol. (Isopropyl alcohol is cheaper and just as good.)
The alcoholic suspension of the fuel components was cooled to 15 C, after which the hot aqueous KNO3, solution was introduced gradually with vigorous agitation whereby the KNO3, was precipitated in the form of very fine particles intimately mixed with fuel components. The resulting product was then washed with alcohol and dried.
The process was also tried:
- using channel carbon black, and NO Hycar MTA
- using wood charcoal that was ball milled, and NO Hycar MTA
- using maple wood charcoal, colloidal sulfur and NO Hycar MTA
- and using a 50/50 mixture of maple wood charcoal, and carbon black powder, WITH Hycar MTA. All of these methods produced black powder equal to the standard DuPont black powder when tested in a "Closed Bomb"
I would be remiss if I failed to mention that powder is listed as an explosive in 18 USC section 841c, and anyone making it would be, in effect, manufacturing an explosive material.
A technique that can be used for the intimate mixing of some pyrotechnic compositions. It involves the precipitation of a substance from its saturated solution in one solvent by the addition of a second solvent that is miscible with the first solvent but in which the dissolved substance is much less soluble. Most commonly, the technique involves precipitation of dissolved salt from water by the addition of ethanol. For example, an intimate mixture of Black Powder ingredients (potassium nitrate, charcoal and sulfur) can be prepared using coacervation. (This is described as the field expedient method of making Black Powder.) In this process one suspends finely powdered charcoal and sulfur in a saturated solution of potassium nitrate in water and then adds ethanol to precipitate the potassium nitrate and carry the charcoal and sulfur with it. The effectiveness of this method is substantially increased if the initial saturated solution is hot, the alcohol is cold and the mixing is vigorous.
ALCOHOL & OXIDIZER SAVINGS
By Randy Peck
I have wondered for a long time if there was a way to remove water from alcohol - it finally hit me! Here's what I've discovered.
This is for the Black Powder makers who use the CIA method, where the potassium nitrate is dissolved in hot water, after which the sulfur and charcoal are mixed in, and after bringing to a boil precipitated out by cooling the hot mix suddenly in cold alcohol.
To get the alcohol really cold, I put the whole can in the deep freezer and keep it there so when the next batch is made it'll be ready. Alcohol does not freeze at reasonable temperatures. This should make really fast powder.
However the process invariably results in the loss of some of all three ingredients, and produces a lot of used alcohol that's mixed with water.
I put the liquid in glass jars and allow it to sit over a period of time until I can see the solids have fallen to the bottom and only the clear alcohol and water and some yet dissolved potassium nitrate remains on top. The potassium nitrate cannot be seen but it's there and can be recovered by doing the following.
I skim the clear liquid from the glass jars and place it in an empty alcohol can (you do save them don't you?). Then I put the can in the deep freezer and let the magic occur. Alcohol does not freeze so it will separate from the water. The extra cold environment causes the dissolved potassium nitrate to further come out of the liquid and both it and the water, which is now ice, will fall to the bottom of the alcohol can.
I use a paint strainer in my funnel that's placed in another can and pour the entire contents of the frozen alcohol can into it. Pure alcohol comes out first and that which is caught in the paint strainer will be the potassium nitrate and ice. I put this on newspaper to dry and later find I have more potassium nitrate to use for the next batch.
It's a surprise to see how much is recovered, not to mention the savings by not having to buy as much alcohol. Recycling at its best!
REDUXING CIA DÉJÀ VU
By Randy Peck
The BP CIA Method "Revisited" article was excellent and I think very timely when considering our current energy costs. Milling for hours to achieve an intimate mixture and acceptable powder would certainly cause the electric meter to spin!
True, energy is needed to heat the mix, but only enough to get the potassium nitrate dissolved and then the other ingredients mixed in and brought to a boil.
True also that the charcoal and sulfur are ball milled together for 1 hour, but with the use of a Sponnenmill and two 1-gallon jars that can be milled together, enough can be prepared to make many 500 gram batches.
So all that is necessary is to merely weigh out the milled powder, the potassium nitrate, the required water, and the super-chilled denatured alcohol and it's ready to go.
It takes a lot of manipulation to get the charcoal and sulfur mixed in with the hot dissolved nitrate solution. When the dry powder begins to take on a wet appearance, it's nearly done.
A word of WARNING here - the pot will boil over! When the mix comes to a boil, it rises rapidly as a fluffy black bubbly mass. If removed from heat it will quickly subside. I never would simply turn on the heat and walk away- this is a process that requires constant attention!
There is a cool down period of 20 to 30 minutes after the mix has come to a boil. Just prior to the time period ending, the alcohol is taken from the deep freezer and placed it in a large stainless steel salad bowl.
The heat is reapplied to the mix to bring to a boil - that black fluffy bubbly mass again - and while quickly stirring it is just dumped into the alcohol and stirred again to cool the mix as quickly as possible. The steam and alcohol vapors are intense and the process is usually done outdoors.
After the mix has cooled it is poured into a cloth that's draped over another container. The ends are gathered ad as much alcohol and water from the powder is squeezed out as is possible with gloved hands.
Then whatever means that works is used to press the powder into "BP Patties" and allowed to dry before granulating. An easy way to determine when they're dry is to weigh them and when they stop getting lighter, they're dry.
One popular trick is to make more than is needed in the spring and keep them up overhead in the fireworks assembly shop where it's hot form the sun heating the roof. By the time July rolls around, there's no doubt they're dry and ready to granulate (break up) and pass through screens to obtain the different mesh sizes.
Finally, the addition of graphite will give your powder the same glossy black appearance as the store bought variety but this is a step I find unnecessary.