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This is an instructional for manufacturing your own homemade German Dark Al powder. Homemade aluminum powder may not be as good as Eckart aluminum powder; however it is practical for use in pyrotechnics. German Dark Al powder is a particular aluminum powder that has charcoal added to it to prevent oxidation while milling. Not only does charcoal prevent aluminum from oxidizing into aluminum oxide as it mills, it also makes the aluminum powder more reactive bringing about an acceptable product for pyrotechnics. German Dark Al powder is a key ingredient in many pyrotechnic compositions especially in low grade explosive compositions such as flash powder. German Dark Al powder can range from a coarse grade such as 100 mesh to a super fine grade such as 7000 mesh. The finer the grade of the aluminum, the more reactive it is.
Materials:
Aluminum foil
Willow charcoal (1 tablespoon)
Ball mill (or rock tumbler)
Steel media
Measuring tape or ruler
Scissors (or your hands)
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Signing UpStep 1Measuring the Aluminum Foil
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No, 2 nights will not be enough. However, it should be good enough to use as a coarse powder for a sparkling effect in rocket tails. I haven’t tried it but I don’t doubt it.
The aluminum powder I made here was used in 70% KClO4/30% Al flash powder and it was pretty fast but it still wasn’t as fast as 70% KClO4/30% Eckart Al (5413 mesh) flash powder. Although I milled for 11 nights the aluminum powder still wasn’t good enough for a super fast flash powder.
I’ve tried the same Al powder with some homemade Fe2O3 for thermite and it didn’t burn the way I thought it would. The ratio I used was 50% Al/50% Fe2O3. I think I was supposed to have more iron oxide than Al for a proper reaction. I still have more experimenting to do so I’ll see.
I hope this helped,
Kendall
http://en.wikipedia.org/wiki/Rust
Did you receive this info from the Anarchist Cookbook because it's most likely false if so.
The heating was obviously caused by a friction inside a ball mill.
Are you using a rubber barrel?
http://www.instructables.com/id/Make-German-Dark-Aluminum-Powder/
You know I haven’t thought about that, that’s a good question. To be honest I don’t know a lot about ball milling materials luckily I found this comment on a thread on sciencemadness.com.
“I have heard of incidents similar to this, some causing quite a bit of damage. A particular incident I recall reading a few years back was an experienced pyrotechnic hobbyist, who wanting some ultra fine magnesium, milled some coarser granules to get the desired particle size. Upon opening the ball mill the magnesium dust instantly ignited causing a massive fireball with a lot of heat, miraculously the man escaped with only mild burns.
Anyway I would suggest you do this: I assume you are starting with Al foil and milling it down over the period of a few days. I would suggest that you open the ball mill and let the Al powder remain in contact with the atmosphere for an hour or two. Do this once or twice a day until you are done milling. While this may seem counterintuitive it really isn’t, aluminum is actually quite a reactive metal and when exposed to O2 it forms a layer of Al2O3 which protects it from further oxidation. So here’s what I suspect is going on, as you mill the Al you destroy the passivating layer while at the same time increasing the surface area by a lot. So when you finally expose the ultra-fine Al to atmospheric O2 it rapidly begins to form Al2O3, and after a certain point enough heat energy is released to ignite the Al.”
To me this makes sense, however I didn’t let my Al have contact with the atmosphere for more than 20-30 minutes. You could do it the other way.
You ask, “I'm just thinking that I could put my mill on a timer when I leave for work so I wouldn't have anything silly happening while I'm away?” and I believe you’ll be fine so long as you expose the Al to fresh oxygen slowly. People on SM have said you can open the lid every 12 hours but I said 8 out of caution from my last accident. I suppose there are other ways of ball milling Al and other pyrophoric metals. The method I use works for me but I may make changes in the future as I grow. As I, you should do more research and experiment. Everyone has trials and errors. You’ll get’er down.
Visit the thread and read peoples comments.
http://www.sciencemadness.org/talk/viewthread.php?tid=14884
SM is very helpful when you have questions. Just research to see if someone has already asked what you were wondering.
To my knowledge atomized Al isn’t supposed to get darker as you decrease the particle size. What are you using the atomized Al for?
http://www.pyroguide.com/index.php?title=Aluminium_%28Powder%29
Also, if, for example, you opened and removed the cap slowly, the flow of oxygen wouldn't be so sudden and abundant, but more steady and controlled. Would this possibly lower the chance of spontaneous ignition?
I suggest that you open up the barrel every 5-8hrs but it’s possible to let it keep running a little longer. I’ve milled my magnesium for prolonged hours and unknowingly gave the powder what it needed as I opened up the barrel to check my Mg’s progress before I had my accident. Before you leave for school and as soon as you get home it would be a good idea to open up the barrel.
Yes! Please do remove the lid slowly. A steady and controlled flow of fresh oxygen will lower your chances of having a spontaneous ignition.
If you do this you shouldn’t have any issues with spontaneous ignition. I don’t know where you ball mill but I would suggest outdoors. Also be aware of your immediate atmospheric conditions. If you live in a humid area the fine pyrophoric metals can react with the moisture in the air.
Go here and read “Fire Fighting Measures”
http://www.jtbaker.com/msds/englishhtml/a2712.htm
I’ve worked with aluminum powder plenty of time and have never had an issue.
That’s interesting; perhaps the aluminum powder was very slow to combust in the abundance of fresh oxygen. I don’t think moisture from your breath would have been sufficient to excite the Al powder and I really doubt static discharge would do it.
Good luck man.