My flash powder will not ignite

[jmguerra]

I have a couple of fireworks books and tried to make flash powder using the 70/30% mix in the John Donner book a "Professionals Guide to Pyrotechnics".

I was quite cautious and mixed it outside on a plywood table, wearing a welding helmet and welding gloves, since the book is explicit on how dangerous different flash powders can be. I believe this mix is the 'safest' formulation.

I mixed 70% potassium perchlorate and 30% Aluminum powder 5 micron in a plastic bowl, with a small paint brush.

I took a small amount and stuck a Visco fuse in a mound, and it would not ignite. What am I doing wrong? I understand this is a basic question and appreciate any advice.

[PyroMonkey]

That is slightly odd; standard 70/30 flash should be easier to ignite. What type of Al powder is it? German dark or Indian blackhead? If not, the characteristics of the Al may be inhibiting ignition. Have you tried to ignite the mixture when confined? Prepare a small quantity of it (10-20g) and fill a small cardboard tube with discs glued on the ends. Wrap it with twine or reinforced tape to add better confinement. See if that yields any better results.

Also, some may disapprove of your technique of mixing the flash in a plastic bowl with paint brush. The chance of building a static charge is potentially high with plastic, and possibly greater with the brush rubbing against the plastic. Look up the method called "diapering" which uses a folding action on an open-faced piece of paper. You could also try sifting the flash through a kitchen type sieve, but avoid pushing it through the screen, which can cause friction.

[Chris H]

Given how he described it, I suspect he has atomized Al, which is likely the issue. Low surface area makes it harder to light. Using it confined as you suggested will probably do the trick.

[Pyrocity]

Diaper mixing is really the safest way to mix. You will have ignition at some point, so do NOT underestimate your mixture. It will ignite, and it WILL do so explosively. This is certainly a case of the aluminum type being the culprit. Atomized aliminum being the most difficult to ignite. Flake aluminums are typically the easiest. The Blue aluminum out on the market has the characteristic of not being able to ignite without being confined, and needs a booster as well. Once those two requirements are met though, then LOOKOUT! it's a salute!

[NWPA]

I am really surprised at how many people are messing around making flash powder.If you want a bigger bang take some smaller things apart until you get 5-10 gr. It is not worth the risk. 50 plus years ago I mixed [diaper method ] about 10 oz total of a perchorate,antimony trisulfide,alum.,sulfer mixture. Took it to back of my farm and lit it. Well that put the fear of god in me. From that day forward never made it again.It is FAR to dangerous. When I think of how stupid I was it makes me shudder. Confine your self to fountains, stars,smokes, it really can be a enjoyable. Noise is not the be all end all. [Well, it could be the end.] Anybody can make a big bang, but a well made fountain, small aerial shells, that takes effort that is well worth it. D