Well, I made a batch of this flash composition today, in the ratio 50:30:20, and I am quite impressed so far. I have only tried it unconfined, and although it burns slowly, it is unbeleivably bright. I plan to test it confined soon. To make it, I ground and seived the KN03 and S first, then weighed out the proper proportions and mixed using the diaper method, the Al is Atomised "grit" type. After mixing with the diaper method, I tested a small quantity which burned slowly but steadily, I then took approxamtely one teaspoon of the powder and ground it VERY gently, and this sample seemed to burn slower, I'm not sure why. The scales I have are really not accurate enough for making small amounts as I did, but they are all I have at this stage, (I made 100g).

I also plan to try this composition pressed into tubes unconfined, as a sort of flare, it wont burn all that long but I think it should look quite good at night.

I would like to hear about anyone elses experiences with this comp. and their opinions of it. I know its not as good as the perchlorate based flashes, but this is all I have to work with.

Cheers.

Have you tried compressing the composition into a block (or tube) with a small amount of binder? If so, how did it perfom with regards to brightness and burn time?

I am not too impressed with this composition at all! I use -325 mesh Al and it burns slow! Admitedly it's bright but I really can't see it working in salutes. It works great for flares though and lighting thermite!

Try substituting the KNO3 with Ba(NO3)2 or Sr(NO3)s for an ever brighter (not colored!) flame.
Because there is no chlorine donor present, the BaO and SrO will emit extremely bright light when heated.

I have experience with this composition. Although I was using dark Al which is much more suitable for flash rather than the -325 Al that most of us Aussies have access to, ;) the composition still did burn quite slow. Confinement is the key here fellers, I made some salutes using kclo4/al and kno3/s/al. I used strong cardboard and used string for extra confinement wrapped the same way you would round a canister shell. The results are quite surprising. I did the test about 4 years ago but if I remember correctly the kno3/s/al produced a much deeper thumping sound and emitted a lower level of light than that of the kclo4/al but was still quite impressive, infact some of the bystanders were more impressed by the kno3 comp.

Good luck, stay green.

Even with 375 mesh aluminum powder I still got pretty impressive results. It burned fairly slowly in the open, but when confined in a 2 x 5/8 x 1/8 inch wall paper tube it was hard to tell the difference in sound between 7/3 and KNO3/S/Al.

I still prefer KNO3/magnesium over KNO3/S/Al though.

It does indeed burn very brightly, if i get the chance il try and get some video footage. The problem is the comp sits there reacting (KNO3 +Al ?) which is obvious since you can smell the strong rottenegg smell of the sulphur and with different ratios of more alluminium the bag will also infact get hot to touch, which is scary (i dumped that mix and hosed it). Apperently adding boric acid will prevent this. Iv yet to try it in a salute since i though it burnt way to slowly but have have used it as a flair that was good enough to see clealy in the dark.

This is my first post, I'll try and make it short and conform to the rules.


I also got some of the same stuff, except with 600 mesh dark german Al. Im gonna see if some salutes will go off with just this Al and KNO3, and with also try with Potassium Perchlorate and Al. Also I have sulfur too, Does that make any kind of difference when added to the Al+KNO3 mix? What about the K percholrate mix?

I've tried the mixture using both KNO3 and BaNO3, but the KNO3 mix was a total failure, while the BaNO3 just gave out white sparks. The object of my experiment was to see whether this mix was feasible for use as a flare to see in the dark (not a signal flare). However, since it just gives out sparks instead of a steady brilliant light, I doubt whether it can be used... Any tips for getting a consistent incandescent flame instead of just sparks? :(

T_Pyro, is the problem that you are having trouble igniting the KNO3/S/Al mix, or doesn't it stay alight. What grade of Al are you using. By compressing my KNO3/s/Al comp rolled up inside Alfoil, about 1cm thick and ten cm long, I was able to make a v.bright flare (like Mg ribbon but a much larger flame). This was ideal, because the foil also oxidised with a brighter light than the composition on it's own. If you are having ignition problems, use a catalyst like KMnO4 perhaps.
The slowest burn rate I can get is about 10cm/s, so it is probably useless as a flare.

scarletmanuka:

About the grade of my aluminium powder:
I really wouldn't know how to grade it, 'coz I made it at home, using aluminium foil and an old food grinder.

I think the problem was with the sluminium particle size, like you said. I gave the aluminium powder another 20 minutes in the grind, and the resulting Al powder gave pretty good results with BaNO3. The KNO3 mixture still does not work, so I doubt whether the problem is with the ignition of the mix.

I'll have to measure the burn rate of mine, but I don't think it was as high as 10cm/s.

I'll try getting some KMnO4, but I've been told repeatedly in the lab that it's "expensive", so I'm not sure whether I'll be able to afford it, let's see...

KMnO4 expensive??? HAHAHA. It should be dirt cheap. I mean really, KMnO4 is one of the most used chemicals.

I would advise againts using sulfur with KMnO4.

T_Pyro-KMnO4 should be available in pharmacies for treatment of athletes foot and as an antiseptic, it maybe a little expensive, but ideally, you need very little as it is just a catalyst.
Vulture- KMnO4/S/Al is alot safer than KNO3/S/Al in my experience. I have stored the former for months, however the latter will evolve H2S gas with in a few weeks, but the Al powder I used has a small oil coating which prevents this.

EDIT
Forgot to add, that maybe you could use MnO2 or K2Cr2O7 instead of KMnO4 if it would help.

I've tried adding MnO2 to other KNO3 based mixtures, but there was very little difference. Of course, the reason for that could even be that the MnO2 was impure: I got it from some dry cells. Theoretically, the evolution of O2 should be accelerated, since MnO2 is used as a catalyst in the laboratory preparation of O2 from chlorates and nitrates. Or am I mistaken?

I was thinking of mixing some thermite mixture along with the BaNO3 /S /Al mix, just to see if there is any difference in the brilliance of the flame, or the burnrate. Is such a mixture "safe" for experimentation, and is there any other thing (incompatibilities, etc.) I should keep in mind while executing the plan?

Well, thanks for clearing up that misconception about KMnO4 being expensive- We use KMnO4 for titrations in the lab, and we're told not to waste it, coz' according to the professors, it's "expensive" :rolleyes:

Sorry I havent replied in a while, my computer had a virus, I am going to soon try this comp under heavy confinement, so I'll let ypu all know what happens. Thanks for all your advice, and tips etc, I'll post my test results here in a week or two.

OK, I tried out some KMNO4 based flash. Composition:
KMNO4:60
S:20
Al:20 (homemade Al powder, unknown grade, particle size= 0.4mm approx.)

The results were far better than any KNO3 /BaNO3 based flash composition I've tried before. Here's a short video footage of the test:
http://www.geocities.com/joydeep_b2002/T_Pyro.html

The burn-rate is just way too high fror use as a flare, but it would make a nice flashbang! I yet have to test the mixture for stability (shelf life, etc.).

T_Pyro: How much are you paying for your KMnO4. there is no doubt that it is one of the easiest oxidisers to make flash with, but on a large scale it is too expensive ie. in Aus: 1kg of KNO3=$2 and 50g KMnO4=$3.80. that is why I am such an advocate of KMnO4 catalysed KNO3 flash. BTW BaO2 (peroxide) is also used to lower the ignition temp of many comps and industrially for thermite by flooding the mix with oxygen.
BaO2 is not an extremely powerful oxidiser: BaO2 --> BaO + 1/2O2 + 148j, but the advantage is that it releases O2 at low temps, making an ideal catalyst.(not really a catalyst just a sensitiser).I tried MnO2 as a catalyst for KNO3/S/Al but had no look, infact the mix seemed to burn slower. I obtained my MnO2 from dry cells as well.
A critical difference between my flash and yours is that i used the ratio of 30%Al 20%S and 50%KNO3 where greenberet uses 20%al 30%S and 50%KNO3.

T_Pyro: How much are you paying for your KMnO4. there is no doubt that it is one of the easiest oxidisers to make flash with, but on a large scale it is too expensive ie. in Aus: 1kg of KNO3=$2 and 50g KMnO4=$3.80. ]

Too expensive? If you search around you can get KMnO4 in 1kg bags for $12 - in Australia. Thats so typical of newbies, find one soruce and give up and say its not good enough :mad: If they had some commitment...
I am releasing my OTC survey PDF soon so stay tuned

Back on topic I have tried 70/30 KMnO4/-325 sperical Al and it worked like a charm. Works in strong polumas with sparklers as fuse and it really really really loud in home made rocket tubes :) If you make salutes with tubes don't bother making end plugs crimp the ends over and fold them over and tape them. This makes them really damn strong, admitedly the salute looks ugly and messy but the results are fantastic. The case bursts the casing not the ends. I have also got very deep booms when using lift powder with this type of casing.

scarletmanuka:
I'm afraid Vulture was right back up there. KMNO4 might not be dirt cheap, but it's far cheaper than what you stated. I got my KMNO4 from the pharmacy, like you suggested. You could even ask some chem supply shops, stating "titration" or "volumetric exp." as the use for the KMNO4. If you're still stuck, send me a check, and I'll mail some to you- it'll still turn out to be cheaper!
;)

blindreeper:
Did you use any catalyst/ sensitising agent in your mix? I tried the same mix, but it failed, most probably because my Al isn't exactly "325 spherical Al"...

Has anyone tried using KMNO4 as an oxidiser in coloured flashes? If so, what coloring agents (chlorine donors, Sr/ Cu/ Ba salts) did you use?

No sensatising agents whatsoever. It took a healthy fire to get going, matches couldn't do it too well.

I don't use enough KMnO4 for it's cost to be a problem. I have tried using it as an oxidiser for coloured flash with SrCl2, but I used Mg instead of Al, it produced the most brilliant red I have ever seen. With CuSO4(anhydrous) and Mg it did indeed produce a dirty green, but it's performance was hampered.
BTW nice pic of the KMnO4 flash. That is what my KNO3 flash with Mg filings, 50/50, looks like.

I’ve made some flares with this composition (50 KNO3, 30 S, 20 Al), they work great. Just press it hard in a thin paper tube (use a sleeve if the tube isn’t strong enough to hold the pressure while pressing), and it will burn very slow, emitting a very bright light (and almost no sparkles).

The Al I use is epoxy grade, I thought someone said it was 300 mesh.

This stuff is also great for lighting termite and other difficult to ignite compositions.

To correct myself: KNO3 mixtures are catalysed by V2O5, not MnO2. Chlorate mixtures are catalysed by MnO2.

scarletmanuka:
Theoretically, Strontium chloride would have been the ideal red flame colouring agent, but I find it to be just too hygroscopic. How exactly did you use SrCl2 in your mix? For that matter, Copper chloride also gives a distinctly blue tinge to a flame, but it, too is hygroscopic.

T_Pyro, at this time of year I do not have problems with hygroscopic chem's, not even NaNO3. To use in my mix, I just added about 10%SrCl2 and grinded together with the KMnO4 before adding the S/Al.

How important is the oxygene balance in this flash mix?
Only 50 part KNO3 seems to be to less.
I´ve tryed to calculate the mix for balance.
My results are 70,4% KNO3
15,7% Al
13,9% S
I don´t know if this is correct but if so and there are other reactions then oxidations, the oxygene balance may be useless.

Yeah I only have access to VERY limited chems, so I am working on the 'poor mans flash' right now, I have had success with 12:7:10 (KMnO4/Al/S) mix look here http://www.geocities.com/schmuckrat/Videos.htm
New round of testing is to come, I'll keep you informed.

The best poor mans flash is Al KNO3 in a 60/40 ratio. Nice colored flame and cheep. I sometimes powder aluminum by putting a rod of it in a drill press and useing a nice high grit piece of emery cloth on it.

I tested a salute containing the Al/S/KN03 comp, and I got a decnt report, short but bright flash, it was confined in a film can bound with a little string and heaps of strong tape, although its not the best flash around I will continue making it for flares as it is extreemly bright, and when pressed has a long burn time, when I get round to making some rockets I would like to work on some paraflares, which reminds me, I actually got my hands on some rockets with paraflares, the rockets shoot to approx 100m then a chute with flare pops out, so I'm told.

I've made some triange crackers with KNO3/S/Al, their very loud, it could be because im using more then 600 mesh Al powder. Heres a 2 gram pile of a 50/50 mix of KNO3/Al being set off: http://www.geocities.com/spiffy_vision/brightness.mpg

@Jumala, most flash mixtures are quite oxygen deficient, this is so that Al powder can burn in the atmospheric oxygen to create a brighter flash.

It is true that the flash mixtures are defficient to allow for the Al to burn in the atmospheric oxygen, but is all the additional Sulfur(%30 by weight) really neccesary? I thought it was just used as a sensitiser as it is no where near as bright or powerful as the Al. Would it be a better idea to replace some of this sulfur with Al.

IIRC (and correct me if I am wrong) the sulphur is used to lower the ignition temperature of the composition, so you dont need a blow torch to light the stuff.

ive noticed that when you add sulfur it burns faster

Depending on it's application, the role of sulfur varies. It has certain properties pertaining to oxidizers, reducers and catalysts.

When used in Black Powder as a 5 percent amount, it reduces the ignition temperature of the mix due to it's own low ignition point of around 205oC to 260oC. When combined with an oxidizer at that temperature, the temperature of combustion increases very rapidly to the point where the carbon in the mix can be oxidized also. Volatiles in the charcoal also aid in a lower ignition point of the composition and enhance the rate of combustion. At this time sulfur is being oxidized to various sulfur oxides and the decomposition products of KNO3 are being oxidized by the created SO2 and SO3 and un reacted S to produce potassium salts such as K2S, K2SO4, KHSO4 etc.

Black Powder's combustion process is very complicated indeed and many different compounds are found in the reacted material along with un-reacted components of manufacture. Due to this it makes it harder to ascertain what effects sulfur has. During it's combustion sulfur is oxidized and it oxidizes other materials in the mix itself.

The main purpose for using sulfur in small quantities with most formulas is to lower the ignition temperature of the mix. It creates a chain reaction which ignites the main constituents of the composition. This reaction can also apply to it's use in flash powders with coarse metal powders. If the particle size of the metal is so coarse, the amount of energy and heat required to initiate the reaction is higher. By adding sulfur you can significantly lower the amount of energy and heat required to initiate the combustion process due to the sulfur and oxidizer burning. When using metal powders with such a small particle size such as 600# or higher, the reaction can proceed without a significant input of energy, thus negating the need for sulfur.

Other effects of adding sulfur to flash mixes include gas production, as combining a metal powder and an oxidizer does not produce any significant amount of gas but rather expands the localized air due to the massive amounts of heat produced during the reaction. By adding sulfur you introduce more gases (SO2, SO3 and side amounts of H2S are quite probable).

From the above gas production, your flash can give out a deeper sound than you would ordinarily get with straight oxidizer + metal powder. Adding sulfur can also increase the mechanical sensitivity of the mix (impact & friction), which is not always a wanted effect.

Hope it helps.