Air Float Charcoal Black Powder

[Steigede]

A few weeks back I tried making some ball mill black powder with the usual ratios. I used Sulfur found at a garden supply store, Air Float Charcoal, and Technical Grade KNO3. I milled it for about 2 hours or so and then added 5% dextrin and granulated it. It's surprisingly underwhelming. Is Air Float Charcoal no good for making fast black powder? I usually use homemade willow charcoal and it comes out faster burning but ran out for this batch.

[Arthur]

"The usual ratios" can be upset if the charcoal is damp because you weigh the water so the mix is off. Maybe dry the charcoal if needed.

2 hours is probably not enough -unless you have prior experience in your mill that says 2 hours is enough.

The wood that was charcoaled is very important. Willow, red alder, eastern red cedar are regarded as good but may be hard to find in your locality (wherever). Pick a known good wood. The old British lore was that you should use the young growth of trees that grow rapidly by water, but that doesn't mention that balsa makes a novelty ultra fast powder.

Edited July 11, 2020 by Arthur

[Steigede]

Yeah I have no idea what this air float charcoal was made from. It should have been very dry. Maybe I needed to mill it longer.

[MinamotoKobayashi]

Hello.

Take a look of this old tutorial of mine:

 

https://www.amateurpyro.com/forums/topic/13068-how-to-make-very-fast-kp/

 

This was made for KP but for BP is the same thing.

 

First to look at charchoal performance please consider that to make a good BP is very important to have a good ballmill and a right sieve.

Wrong rotation speed, diameter of the barrell, diameter of the media, kind of the medias, ratio of the chems vs the medias, diameter of the granulated grains

are the main reasons of BP issues!

I always used commercial pine airfloat charchoal from Pyrogarage and I have always obtained a damn fast granulated BP!

[Arthur]

Assuming that you have had prior batches of good BP from your equipment and method, yes, suspect the charcoal. Re-mill the powder for another two hours to look for improvement, but look also for a better charcoal.

 

Locate your local tree surgeon, ask him if he has any willow wood, or red alder. Builders' rough 2 x 4 may well offer a reliably available source of useful wood -even at a demolition site. Just don't use treated wood inc decking.

[Mumbles]

It's the charcoal. Commercial airfloat is kind of garbage for whatever reason. Long milling times can get it passable. It tends to be made from oak primarily due to waste streams. Might be harder, might be higher is ash, might be under/over carbonized, I've never had a good answer. Basically homemade is always better. Use a good charcoal and thing will be better. Longer milling may also help.

[MinamotoKobayashi]

Charchoal porosity is another important variable to make a good BP.

You can ballmill for longer time the charchoal but please consider that if You use lead media, also if antimony hardened, You can contaminate the powder.

and lead/antimony are a bad boys. To ballmilling single chems is better to use stainless steel medias (or, if You want to spend much more, brass medias).

[Steigede]

Thanks for all the great replies! I've made better, faster BP in the past with this ball mill and lead media and it was with homemade willow charcoal. So that seems to be the culprit. I have some 2x4 scraps laying around so maybe I'll try turning some of that into charcoal this weekend. I've been keeping an eye out for willow trees around here and I've only spotted one on private property.

[Bourbon]

Check with your local tree trimming services. They've usually got the hook up.

[Steigede]

Ooo good call

[justvisiting]

Milling the charcoal by itself with stainless steel media first will make the powder a little better, and using more than 15% charcoal will make a distinct improvement. Testing has been done to prove that 'inferior' charcoals can make good black powder. Testing has been done on oak charcoal also, and it can make very good black powder. I've done it. But, if we stick to 75-15-10, don't pre-mill the charcoal, and don't use long mill times, inferior powder will result.

[MinamotoKobayashi]

It seems that milling all the chems together soaked in ethanol for long time with stainless steel medias (or even better brass medias) create a damn fast black powder.

Surely this procedure intimately mix all the chems. I read somewhere that sulfur and potassium nitrate penetrate the charcoal pores thanks to the continue hitting of the medias one against the other.

[justvisiting]

MinamotoKobayashi, milling the charcoal by itself with stainless steel media smashes the walls of all the cells and makes a very dense, non-porous, non-airfloat powder. I don't subscribe the 'forcing stuff into pores' theory. Neighbor J has done some wet milling, and had some safety issues. Maybe he'll chime in about that, I don't remember the details. I make my BP with super-milled charcoal, milled potassium nitrate, and rubbermakers sulfur. I screen twice through 40 mesh, and either screen-granulate, or puck and corn. I have made lift with commercial airfloat as 70-20-10, but 75-20-10 might be better. Airfloat charcoal is NOT very fine (-150 mesh or so), so super-milling it first would be advised. Maybe milling it with the sulfur would make an improvement too.

[kingkama]

IMO superfast powder is needed only if you use ball shells, cylinder requires some smoother or tends to go off in the gun, so as was said faster BP are usefull as break charge but with the 15 % shell weight and a longer gun you can also reach the required altitude. Granulation and drying time are far more important that anyone tends to minds, surely alcohol wet milling is a big plus, but in 2 hours with a decent ball mill and good quality charcoal you have interesting results. Commercial pyro are less precise than amateur thinking because 1000 pieces cannot be all perfect.

[MinamotoKobayashi]

I use supermilled granulated F2A BP only for break 2,3 and 4 inches shells as Shimizu suggest. For 5 inches and above is necessary to use coated rice hulls: seven parts of meal BP for every part of rice hulls. For a good boost replace the last layer of BP with a layer of KP. In my shells I always do an overboost applying two layers of KP. The results are spectacular with no blinded stars and simmetrical aperture. Since my shells are always rocket lifted I do not use BP as lift charge.

And yes, alcohol wet milling, almost for me, create in two hours a damn fast BP!

[SeaMonkey]

Just Visiting,

 

Your comment about using more than 15% of the Inferior or Poor Performing

Charcoal is one that I'd heard before. I can't recall where just now but I believe

it was from an article about how in the olden days tests were conducted to

determine what percentage of various charcoals produced the greatest amount

of gas when the Black Powder was ignited.

 

My own experience has shown on many occasions that a slow burning Black

Powder composition can be due to insufficient percentage of the type of

Charcoal used. I've tried 20% and even 25% from time to time with very

interesting results.

 

For propellant purposes, the mix which produces the greatest amount of

gases is the best. It need not be super-fast in an open air burn.

 

Afterthought. I just remembered that when a Powder lacks Charcoal it tends

to produce more residue. A good Powder should produce almost no residue.

 

Of course, too much Charcoal may produce more residue as well, but it is easily

distinguished from the the residue of not enough.

Edited July 12, 2020 by SeaMonkey

[justvisiting]

SeaMonkey, I read about varying the charcoal percentage in a series of articles about black powder in American Fireworks News (AFN). The 3 articles were written by Ken Ganney and Richard (?). I've done my own experiments with mesquite charcoal and with commercial airfloat. I wrote an article too, about using commercial airfloat for lift. With my own hot water method, I've made hobbyist amounts of 70-20-10 with the mesquite charcoal that gave an average flight time of 8 seconds in the baseball test, using 14 grams (half an ounce). I can't remember if I posted about it here. Sorry if I repeat myself.

 

The way I look at it is the high ash charcoals have less fuel value. So, we need to use more. The minerals in the ash don't participate, they just slightly dilute the BP, in my opinion. The observations about the residue make sense to me too.

 

I've meant to test commercial airfloat charcoal to see what the best powder I could make from it would be, but I never got a round tuit. I've made lift with commercial airfloat using the same hot water method. I never was happy with my choice of 70-20-10 as the alternate formula. I meant to try 75-20-10, but I messed up, and kept using 70 instead of 75 for the potassium nitrate. I'd like to keep the nitrate/sulfur ratio constant, and only vary the charcoal amount. I enjoy the challenge of teasing performance out of black powder made by different methods. It's not everybody's cup of tea, for sure

[Arthur]

When BP was made for all military purposes, it was made to a standard speed by mixing fast and slow batches together according to ballistic tests.

 

If the OP wants powder as fast as his willow BP then either extended milling is one option or addition of some balsa or vine BP (Ultra fast) is required.

[MinamotoKobayashi]

Sorry, one school tell that overmilling the charcoal create a non-porous, non-airfloat, slower BP, the other school tell that the procedure create a faster BP ... a little bit confusing for me.

Also, I tried also puck-and-corning method and I have obtained a terrificant slow BP.

Here is my complete tutorial:

 

https://www.amateurpyro.com/forums/topic/12899-how-to-make-hot-bp-indoor-safely-lab-intensive/

 

Take a look of the Simoski reply, it is very important for those who follow this system ...

 

By the way, what means "OP" ?

[justvisiting]

OP means 'original poster', the person that started the thread.

 

MinamotoKobayashi, I was the one that said that super-milling (not over-milling) the charcoal creates a dense, non-porous, non-airfloat charcoal. However, I didn't say it makes slow BP. The whole objective is to have the most intimate contact between the components, without milling a complete mix. At least, that's MY objective. My research has been done to make black powder with the same properties as commercial black powder, or the same properties as milled, screen-granulated powder- but without the potential danger of milling a complete mixture. I have identified the charcoal component as the limiting factor in black powder speed. Milling complete black powder mixtures does a less than ideal job of milling the charcoal. The charcoal is 'protected' from milling to a high degree of fineness by being dispersed throughout the mixture. Milling complete BP mixtures gives good intimacy of incorporation by forcing the powders together, and I do believe that the potassium nitrate and sulfur are forced into the pores of the larger charcoal particles. Super-milling the charcoal and screen-mixing it with the other (also milled) components gives good intimacy of incorporation by a different route, but in the end, we arrive at the same place.

 

Screen-granulated powder will burn much faster than pucked, corned powder because the fire has many paths to get through the whole lot. Commercial black powder burns from the surface inward. There are also 'some' firepaths, but certainly not like there are in screen-granulated powder. If black powder is compressed to a density of +1.8 when pucking, the burn rate goes down, because the 'openness' of the grain is less than powder pucked to 1.7. Because of this, it's been proven by scientists that commercial black powder made with more dense charcoal will burn faster than powder made with less dense charcoal. This is because the grains of powder made with the denser charcoal will have a more open structure than powder made with a less dense charcoal (if both powders are pressed to the same density).

[Arthur]

Back in the days of military BP use the standard formula was used partly to reduce the amount of corrosive gasses in the gun barrel by complete combustion. A steel barrelled gun (especially naval) would have a life rating before the corrosive gasses damaged the bore too much.

[carpyt]

Thanks for all the info everyone!

[rellim]

The trendy wood to use for homemade charcoal in the U.S. is pet bedding consisting of shavings of eastern read cedar.

[Steigede]

The trendy wood to use for homemade charcoal in the U.S. is pet bedding consisting of shavings of eastern read cedar.

Huh, interesting. For this batch I just used pine 2 x 4 scraps. I'll see how that turns out.

[Steigede]

It was totally the charcoal! Here's a quick video of the difference. I made some pine charcoal over the weekend and whipped up a new batch of black powder. Milled for roughly the same time.