Posted 08 June 2004 - 09:09 PM
Firstly, permanganate flash powders. There are several formulas using potassium permanganate, which I suspect is why people do occasionally enquire as to where this oxidiser can be got. They should be left well alone. All flash powders are sensitive, and there is a risk that they may be ignited by friction, static, impact etc, but the safer ones, eg 70:30 and buffered nitrate flash, will not spontaneously ignite (or are at least very unlikely to). Permanganate compositions will, and often do. They will also ignite from the slightest friction or impact. Furthermore, the safer flash powders will not burn you skin or give you manganese poisoning on contact, like potassium permanganate does. There is no need to use permanganate flash powders, much safer formulas exist.
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In TIF 10, Ofca advises that chlorate flash powders not be used, and I personally have not, and will not use them, as the two flash powders I will give later have been plenty sufficient for my needs. However, other people have used them successfully, and whilst they are probably not really safe, they are a hell of a lot safer than permanganate powders, and are of similar power.
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I rarely use flash, as for me BP is much cheaper and easier, and faster burning, and less likely to go off without being told to. The only time I use flash is when I want a bright flash, eg for bottle rocket headers. On the some occasions when I do need the stuff, I use the following, very common formula:
Potassium Nitrate.........50
Sulphur.......................30
Aluminium...................20
Boric Acid (Optional)....+1
I haven't got around to getting any boric acid yet, but I have so far I have mixed the stuff in small quantities and used it within a couple of days. If you were going to have it hanging around it would be a good idea to include the buffer.
The aluminium I use is home made, probably flake shape, and passing 200 mesh. The potassium nitrate and sulphur are ball milled for several hours. The ingredients are diapered together. The resulting powder seems to burn a little slower than good meal BP, but brightly. Under good confinement, it produces a similar report. Using a real flash aluminium would no doubt produce a much punchier powder, but as I said, I use this to produce a brighter flash than BP, not a louder bang, so that is not a problem.
This powder is said to be a little more forgiving than perchlorate based powders, as the tendency for accidental ignition is lower and the critical mass is higher. However, this should be treated as useful increase in safety, not an invitation to be rough with the stuff. The same precautions should apply as with any other flash powder.
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Another way to achieve a more pronounced flash than with straight BP is to add some aluminium powder to meal BP, and use that in the same way as flash. The amount is not critical, so for small quantities (eg enough for one ?? rocket) you can just judge the amounts by eye (once you know what they look like). A good start point would be:
Black Powder....90
Aluminium........10
Boric Acid.........+1
This is rather like a nitrate flash as above, so again, the same applies for the boric acid. The flash is not as bright as with the above formula, but more so than with BP. This is in fact my most commonly used "Flash Powder" as it uses relatively little aluminium, and is very easy to prepare in small amounts. This formula resembles a fountain formula, but since flash aluminium rather than flitter is used, it will be more sensitive so should be handled with care.
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Finally, for ground salutes, why not use BP? Personally, I mostly use them during the day, when the flash is not that noticeable anyway. If you are going to use a salute in daylight, you can just save yourself the trouble and expense of flash powder by using good ol' BP, or (less preferably) H3. If you do have access to dark aluminium, so actually could make a flash powder that is significantly faster (louder) than BP, then there might be an incentive there, but a bigger BP salute could produce the same effect, and even small BP salutes are probably plenty loud enough. For occasions where you want a flash, then the BP and Al formula is, IMHO, probably the safest and easiest to use.
