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Author: Subject: Flash Powder
hashashan
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[*] posted on 3-9-2007 at 21:53


I prefer to use Mg flashes, they are much more powerfull then Al
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[*] posted on 4-9-2007 at 12:54


Mg flashes are not suitable for long term storage. Even unmixed Mg powder in contact with air will oxidize to uselessness rather quickly.

Mg/Al flash has more of the stability of Al based flash, and some of the speed of Mg based flash. Chinese commercial cylinder salutes made with Mg/Al 50:50 granular powder have been available in the US. The ones we've used were quite good.
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[*] posted on 4-9-2007 at 13:09


ANY KMnO4/metal mixture is to be treated with respect and care. 1g quantities can blow off fingers and create dangerous shrapnel (speaking from experience here).



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[*] posted on 4-9-2007 at 21:59


Bert,

Really depends on where you are located. In my neck of the woods.. mag flashes will last for years and years.

hashashan,

I disagree that mag flashes are more powerful as that is a subjective term. Mag flashes are certainly easier to ignite and possibly burn faster but put out slightly less energy than aluminum or mg/al ones.

Just my opinion based on years and years making a living working with these types of reactions.




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hashashan
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[*] posted on 4-9-2007 at 22:46


Al is problematic gor me ... I can get only 325 granular Al here (the dark i should make myslef and didnt try yet). Mg however does make one hell of a flash when mixed with KClO3.
And regarding the storage.... I dont store it so i dont kow how stable it is. I dontsee a reason to store it.
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[*] posted on 5-9-2007 at 16:53


I remmeber about a year ago when i had some KMnO4 i took some flint and carefully filed it until i had just a pinch(this is actually very hard to do because a minor spark will catch it on fire and you have to start all over) I mixed the flint with KMnO4 and what i got was an amazingly powerful flash powder probably not very practical but very strong. just wondering if anyone else has tried this.
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[*] posted on 5-9-2007 at 19:26


You can buy cerium metal reasonably easily - lighter flints are cerium and iron.
Read a few pyrotechnic sites for ideas - but be careful, always.

Regards, Der Alte
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[*] posted on 17-9-2007 at 21:40


I do believe you will encounter some relative difficulty preparing your own dark aluminum. Believe it or not, but 325 mesh Al ball milled with lead until it is dark with contamination isn't quite what you'd expect to get from Eckhart.
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hashashan
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[*] posted on 17-9-2007 at 23:34


How about steel media?
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Mumbles
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[*] posted on 18-9-2007 at 07:46


I'd suggest going and doing some reading about the processes that go into manufacturing dark aluminum. And no, steel media isn't going to give you dark aluminum either.
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nitro-genes
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[*] posted on 18-9-2007 at 10:01


Errrr, I've made my own dark flake aluminium for years before the commercial stuff became available to me. Just an airtight rocktumbler filled half with 1 cm diameter steel balls. Took about 5-7 days to go from shredded aluminium foil to a dark grey powder, which performed just as well as dark german, meaning 100 mg's 7/3 Kperc/Al on the tip of a knife making a distinct and loud POEMP sound with white flash flash upon ignition. Compared to the commercial stuff I have now I see little difference, other that it safes a lot of effort to simply buy it. Without screening there is some larger fractions of particles left, creating longer lasting white sparks, but even with the commercial stuff you occasionally see this. Maybe the oxide percentage is somewhat higher as well, but it is definitely not impossible....

Why making two single-lined posts about what ain't possible, if you could have made 1 post with at least some clues or directions where to look?!

[Edited on by nitro-genes]
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[*] posted on 18-9-2007 at 21:45


Dark aluminum, simply put, is not prepared by just ball milling it. Dark Aluminum has some carbon and other things coating it's surface to prevent an oxide layer of the normal extend from forming. Dark color does not neccesarily equate to dark aluminum. In the size and shape it is in, the oxide layer would consume a great deal of the particles. As I am aware, the aluminum stock is rolled into a thin foil, and glued to some thin paper. This is then shreded by mechanical means, stamp milling I do believe. The paper is then burned off in an inert atmosphere, giving the characteristic dark color from a bit of carbon being left over. There is some speculation of aluminum carbide being formed, and increasing reactivity at this point, but I have seen no real evidence proving this. It is probably then reduced again by stamp milling or ball milling.

So, dark aluminum involves integrating carbon into the outside layer. Simply ball milling until it is pitted and oxidised appearing dark will not give an equal product in my opinion.
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[*] posted on 19-9-2007 at 06:14


It is a common misconception that all grades of dark aluminium go through the roasting process. I saw a photo once of one of the fastest grades of Eckhart dark aluminium and I can say it looked exactly like the stuff that came out of my ballmill. Not like the german black aluminiums, but rather a dark grey with blueish appearance due to the lack of carbon. IIRC, Shimizu's himself mentions in some of his books that dark aluminium can be made by ballmilling coarse aluminium powder with 5% oil to reduce oxide formation. An airtight milling drum is a necessity, else you will indeed find only some oxide left after a week of milling. I read once that even the best grades of dark german aluminium can contain up to 20% oxide/inerts, so this probably something that is inevitable with decreasing particle size, unless some special coatings are aplied like for alex...

[Edited on by nitro-genes]
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[*] posted on 19-9-2007 at 09:48


He was discussing flash, and that generally makes me automatically go to the blackhead types. A dark aluminum, something like 809, doesn't result in nearly as strong of a flash as the finer materials. I would think that addition of oil before the milling would result in more of a bright flake Al. Perhaps the stearic acid used in the bright flake I am familiar with has some other sort of property that prevents it from darkening, or is made in a different process. I would imagine stamp milling would be more often used, as it should be more efficient in this type of process.

The drums of the blackhead Al (Ekhart 5413-H) I've seen are something like >94% Al <2% Carbon <2% Al2O3 <2% Stearic Acid

Really what I was trying to say is that just because an aluminum is dark in color, doesn't neccesarily make it a true dark aluminum and suitible for flash powder or other uses that require fine flake material. Dark from roasting or wrinkles/scratches/etc is definatly different than dark because theres a considerable amount of lead or oxides in there.
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[*] posted on 20-9-2007 at 06:47


I am aware of a grade of India Black that unquestionably had a share of carbon in it. A PGII writer did a little piece on dark Al and found that some had as much as 12% carbon and that some had additional C added as an adulterant. There was a grade of India black that was considered as a "rip-off" due to the level of carbon present sold by a large pyro supplier some years back. In the older posts I have the names and details of this whole issue.

I too have made a respectable grade of dark using Tank or Tractor ball bearings (1.25") in a rock tumbler turned ball mill but my starting material was Alcan 808 @325. Tumbling time was 48 hours and I had a dark that was better than most I have seen sold. It was attempted twice again with two pounds and larger starting Al. I shy away from foil due to the coating, etc. But I have used simple floor shavings that were ridiculously large and mostly granulated. I imagine foil could work if it was determined to be uncoated, etc. Even if it was coated the material may not be such a big deal as there has been Al sold in the past with Teflon in it and it was unusually reactive.

Same time and I had some very, very fine Al. Similar to 5413, this material was very good. In that I maintained this for about two weeks as I had a lot of floor sweepings and the price was right (free). Due to the make-up of my medium I had flake of course. I also tried this with spherical Al and received high grade flake from that as well.
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[*] posted on 30-9-2007 at 04:26


This summer i made many flash powder salutes using KMnO4, Aluminium and sulfur (6:2:2). I think if you handle it carefully and you do not store it, you should be fine. The powder was very powerful. I also tried to place 4gr of this flash in an open plastic vitamin container. The ignition resulted as a nice bang (like gun) and a big and beatifull flame from the hole. The tube was intact, and i was been able to use it many times.

The sulfur I used was a high purity one, I bough it from my local pharmacy.

Here's a clip of 8g powder http://www.youtube.com/watch?v=olwzirU-qso

[Edited on 20-07-2007 by .50AE]
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[*] posted on 16-7-2008 at 02:24


Here's one without metal powders. 2 vol. parts KClO3 and 1 vol. of gallic acid (O.B. precise 74.24% KClO3 and 25.76% gallic acid, %by mass). This mixture decomposes immediately on flame contact about as quickly as flash powders unconfined, but there is little flash and a lot of smoke. It is also very friction sensitive.
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[*] posted on 15-8-2009 at 01:07


As with very early posts, I too am unhappy with my Aluminium. It was bought from Ebay however - so I was not expecting miracles - but it's odd...

It looks very fine, but I have no mesh size for it. It looks very pale and not dark at all - I presume it is atomised with a level of oxidation. With NaOH it liberates Hydrogen fairly rapidly, though this would be expected of even heavily oxidised Aluminium. And Thermite seems fine with it.

However, with Chlorate and a trace (Please don't eat me anyone) of Sulfur - zilch.

In short I'd be interested at milling my own. From quicksilver I gather that tractor bearings make ideal milling media, but what about the container we are grinding it in? Stainless steel? Also, what should they be coated with/should antioxidants be added?

Tr
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[*] posted on 21-8-2009 at 07:04


The medium should be offset by the container....If it's steel, then the container should be rubber like a rock tumbler - if it's ferric, use lead as your tumbler medium. Just be wary of spark production - no big deal. I have made some DAMN fine Al with a rock tumbler and some cheap heavy shot; starting with some aluminum foil cut into strips and placed into a blender first to get it reduced down....
Depending upon the size of the devices; pounds at a time!
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[*] posted on 3-10-2009 at 10:09


I had a friend round today and made the mistake of showing him my lab. He would have been bored to death by the thing I wanted to do (redistill the ethanol I have collected) and so I thought I'd try to prove there were exciting things too by making some of the flash powder given in the first post of this thread. I made about 20g in total. We set off a few .5g amounts which made nice flashes with a small 'whoosh' sound. I noticed however that glycerine wasn't really setting it off - uncontained it didn't at all, and when I used a tiny plastic container it took a good 45s. After a few such flashes we took the remaining 18g or so, put it in a small glass container on some bricks next to a wall, placed some bags of earth around it, added a ml of glycerin on top, screwed on the lid and went about 10m back. After a tense minute, nothing, after two, still nothing...two and a half, nothing. I assumed it hadn't worked for whatever reason so avoiding the container we went back inside for about a minute to collect the equipment that needed washing. Just as we turned to leave, 'BANG', a huge flash, and the sounds of bits of glass smashing to the floor.

There was no real safety threat, we had goggles / gloves on and the glass didn't travel far. But it was one hell of a shock.

My question is: Why so long? When I put glycerine on KMnO4 normally it lights in about 15 seconds, so why now were the drops taking ages or even failing to set it off?
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[*] posted on 3-10-2009 at 17:00


I'm going to be my usual safety nagger here: when ball milling reactive metals, if your mill jar is too well sealed, you may get a catastrophic ignition when you open it. The man who wrote the book on amateur ball milling got a near-fatal sunburn from milling magnesium & opening it - the flame was hot enough to radiate huge quantities of ultraviolet light. His skin never fully recovered and luckily he wore safety glasses or he would have been instantly and permanently blinded.

Other than that this looks like fun :) as long as one respects flash powder. Most of the fireworks factory explosions in the news result from multi Kg of flash powder accidentally ignited. "Good" flash powder will go supersonic (make a bang) in an open pile of somewhere around 1 gram or less...

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[*] posted on 3-10-2009 at 18:41


Quote: Originally posted by Mossydie  

My question is: Why so long? When I put glycerine on KMnO4 normally it lights in about 15 seconds, so why now were the drops taking ages or even failing to set it off?


Two big factors are the water content of the glycerine, and the temperature of the air. Add a drop of two of water to you glycerine and it will work much faster, unless the temperature is really cold.

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[*] posted on 4-10-2009 at 12:04


Regarding slow rxn of the Al/KMnO4 and glycerin, if you are using flake Al, it will very likely "coat" the KMnO4 and somewhat isolate the contact w/ the glycerin. A small addition of EtOH or other low viscosity polar solvent should speed things up. Please do test before scaling-up.

As previously mentioned by others, KMnO4 is an unpredictable oxidizer and has maimed many experimenting w/ it. Better to stick to the tried-and-true standard ones; safer/ more predictable.

Best!
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[*] posted on 5-10-2009 at 11:46


My Al is Ekhart German Dark powder, so really top notch. But yes it is flake.

On the the plus side, KMnO4 is easy to get hold of (something to do with fish tank cleaning) and it means I don't have to use my equally unreliable fuse. It's a KNO3 / sugar one and burns well but sometimes just stops, unpredictably. I think I need three strands braided together to prevent this.

Maimed? It would need a pretty huge amount to do much damage surely? - even if I had been right next to the bit I set off, I think the danger would have been the glass flying rather than the explosion itself.
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[*] posted on 15-10-2009 at 05:30


For those that can't buy Al powder, it can be obtained from paint. Just dilute the Al paint with paint thinner (approx. 1 par paint to 5-6 parts of thinner), wait a few days so that most of the Al settles to the bottom of the container (most will settle, the finest particles could take more than a week to settle). When the Al settled suction of the liquid (be careful doing that so that the powder doesn't get disturbed and floats back in the liquid) and add again some thinner (don't know how much exactly because I haven't measured the amount, but less than the 1:5 ratio) and again wait for the Al to settle. I repeated the process three times to remove most of the organic material from the Al. When the last step is finished suction of the liquid and let the Al to dry.

The Al powder obtained this way works good when mixed with KMnO4 (even with out sulphur), but I don't know how safe is to mix it with KMnO4 as some organic material will remain on the Al and that could cause it to be unsafe (perhaps even to self ignite). I never stored the mixture, and only used it a few times for small salutes.

Perhaps It would be easier to just dilute the paint with thinner, filter out the Al and wash it with some solvent but as the Al is quite fine it could cause problems with filtering if fine filter paper and vacuum filtration is not used. Using filtration and washing would also remove much more organic material from the Al so it would be much more safer to use for various pyrotechnic mixtures.

Also zinc can be extracted the same way from zinc-containing paint.

[Edited on 15-10-2009 by Zinc]




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