823 replies to this topic

[Potassium chlorate]

Fast flash powder is interesting for about 5 minutes. After that initial "blast", you will quickly find yourself dreading the mixing and handling of the stuff. At least that's my experience with it.

I'm afraid of it and fascinated at the same time. The fastest flash powders are tremendously powerful. I'm not afraid of handling a few grams of it, though, like 1-3 grams. It's still dangerous but you don't have the same instinctive fear as when you handle several grams.

[pyrotechnist]

Right I know flash powder is a taboo subject but I am currently trying to make it, as much as I hate the stuff, and it will not work no matter what I do. I am using the standard 70/30 perc, aluminum formula and the diaper method for integrating them both. The aluminum is from Tiranti and is pretty good. The problem I am getting is that the dam stuff just will not burn fast at all, it is worse than un-milled bp! I just ain't sure as to what the problem may be. I also have tried the kno3 based flash using the same parts and it's still, how can I put it...... SHIT!!


It burns more like a fountain mix when confined producing a nice bright light but nothing more. Any help would be appreciated, I am making the stuff for my cakes finally.

[pyromaniac303]

I thought the stuff from Tiranti was spherical and something in the region of 300-400 mesh? Without fine or dark flake aluminium or some of the incredibly fine (1200#~) spherical aluminium powders the Americans have access to, you won't be making usable flash.

Edit: Just taken a look at the Alec Tiranti site and its 250#, only really of use in fountains and streamer/glitter stars...

Edited by pyromaniac303, 08 January 2009 - 11:02 PM.

[pyrotechnist]

That kind of sucks I may just dump this 5g pile in another tube and do a re-test again see if anything changes though I doubt it.

[Gary]

That kind of sucks I may just dump this 5g pile in another tube and do a re-test again see if anything changes though I doubt it.

Have you tried ball-milling your Tiranti spherical aluminium?
Ball-milling should flatten-out the spherical aluminium particles and tear them up; eventually you'll get a very fine aluminium dust that burns fast enough for flash.
A word of caution: ball-milled aluminium can be pyrophoric (the particle size is so small and reactive that it could spontaneously combust in the oxygen present in air).
It is a good idea to vent the jar every so often in order to allow the aluminium oxidise in a slow and controlled manner, otherwise you might get a violent, very, very hot flare-up when you finally open the jar!

[pyromaniac303]

That would do it, although you would never get as good quality material as the german dark aluminium.

Also note that you must not use lead media for milling metal powders, as the lead is softer than the aluminium, so you may end up with a high percentage of lead contamination and a very poor resultant powder.

It is far safer to use a seperate set of media and milling jar for milling metal powders, but if you must use the same jar and media, clean them thoroughly and be sure there are absolutely no particles of aluminium left on either.

I've heard that chrome-steel media is the best for milling metal powders but haven't tried it myself.

[knackers]

De ja vu,
i've been here before , " months ago "

if you want to mill your aluminium fine enough, you need to do one of 2 things,, a hammer mill, ( which is probably out of the question ) or, you need a stainless steel mill barrell with stainless steel milling media,, ( to quote a leading physicist whom is a metalurgist lecturer ) "" thats how we do it"....... and it needs to be done in an oxygen deficient enviroment..... ie, a sealed barrell with an inert enviroment,,,, there maybe other ways, but please don't reply with a ,,,,,,,,,,, thats too dangerous,,,,,,,,, i can't be bothered going through all that again.......

..... how good is your kclo4 ?

Edit...... or just buy some dark german or indian blackhead...... ( no mucking about )

Edited by phill 63, 09 January 2009 - 06:04 AM.

[digger]

De ja vu,
i've been here before , " months ago "

if you want to mill your aluminium fine enough, you need to do one of 2 things,, a hammer mill, ( which is probably out of the question ) or, you need a stainless steel mill barrell with stainless steel milling media,, ( to quote a leading physicist whom is a metalurgist lecturer ) "" thats how we do it"....... and it needs to be done in an oxygen deficient enviroment..... ie, a sealed barrell with an inert enviroment,,,, there maybe other ways, but please don't reply with a ,,,,,,,,,,, thats too dangerous,,,,,,,,, i can't be bothered going through all that again.......

..... how good is your kclo4 ?

Edit...... or just buy some dark german or indian blackhead...... ( no mucking about )

HeHe

Be careful opening the jar when finished though etc etc (I have heard of a few instances where people have had spontaneous ignition and some nasty burns to their hands).

I have not done that procedure (I just buy dark flake), but I am sure there will be a safe procedure to allow the metal to slowly oxidise after inert milling to prevent spontaneous ignition.

Edited by digger, 09 January 2009 - 08:19 AM.

[pyrotechnist]

The only problem is I cannot find a supplier of dark aluminum accept at one place were it is 10 pounds for 100g of the stuff which is pretty expensive. I have loaded up a tic-tac container with 10g of my shit flash all celataped up, hopefully it will work but wont build my hopes up. Thanks for the help up to now, I do not have a ball mill but do have a vibratory mill and I assume coins would work as media being that they are made from steel.

[Potassium chlorate]

You've got mail.

[Bonny]

The only problem is I cannot find a supplier of dark aluminum accept at one place were it is 10 pounds for 100g of the stuff which is pretty expensive. I have loaded up a tic-tac container with 10g of my shit flash all celataped up, hopefully it will work but wont build my hopes up. Thanks for the help up to now, I do not have a ball mill but do have a vibratory mill and I assume coins would work as media being that they are made from steel.

I wouldn't grind Al (or almost anything else really) with steel. The risk of spark as well as contaminating the product with steel are no good. Stainless steel would be better.

[TCblastmaster]

My first attempts at making a flash comp were also very disappointing. That was despite using 2 micron dark flake Al with KClO4 that had been hand ground for an hour in a pestle and mortar and then mixed thoroughly using diaper method. 2g unconfined burned like fountain comp. Doubting the quality of my Al I examined a sample of the comp under the microscope. This revealed the problem; tiny sponge-like black Al particles mixed with white crystaline boulders of perchlorate - not exactly an intimate mix. To dispose of the remaining 8g (don't even think about grinding it further once the two are mixed!) I put it in an open ended tube and added a piece of fuse. Surprisingly it went off so violently that it left me deaf in one ear for a few hours, blew a hole in the lawn and bruised my knee despite me standing 10 feet away!

Conclusions: Perchorate must be extremely finely ground to create an intimate mixture; clearly mass and degree of confinement are important factors that can optimise the performance of even poor quality flash - perhaps even one containing atomised Al; use a fuse of sufficient length; above all treat such comps with the utmost respect and don't add S or any other sensitiser to something that is already very energetic.

I had considered making my own dark Al at one time. The proposed method involved first beating folded paper-backed aluminium foil on an anvil to make the layers super thin, then heating the stuff in an oxygen-poor container to burn of the paper (similar to making charcoal), then grinding/milling the Al to a fine dust. I think this method approximates the actual process used by the German manufacturers but I have never tried it.

TC

[Potassium chlorate]

My perchlorate used to be better too, I think. Maybe they make the particles that size to avoid people from making powerful flash?

[pyrotrev]

It's quite important that the KClO4 doesn't "clump" which it will unless it's in very low humidity or unless a free-flow agent is added - MgCO3 is meant to be good for this, though I'm doing some experiments with micronised graphite which makes the mix less mechanically sensitive. Otherwise your grinding can be in vain - you just end up with lumps of aglomerated fine powder.

[Potassium chlorate]

I made 1 gram of KClO4/Mg/Sb2S3 flash yesterday just to test it. It said "thump". The ratio was 7:2:1 due to my scale which just has an accuracy of 0.1 gram. Maybe 6:3:1 would have been better. And yes, I know that Sb2S3 should be avoided, I just wanted to test the mix compared with the usual 70:30.