I know, I find it hard to believe, too. Permanganate flash gets bandied about as being "unstable," "sensitive," etc.

Recently I tripped over a quantity of KMnO4 and, in the old "finding a use for a chemical" tradition I set about making some flash powder with it to see how well it performed compared to my usual potassium chlorate.

I mixed a batch of 600-ish mesh aluminum and permanganate ground as finely as it would go in my mortar and pestle (separately!) in the old 75/25 ratio. I made two grams of the stuff. It seemed like a reasonable place to start to me.

So, I went out to my crucible and poured out about half a gram, stuck in a piece of visco, lit it, and... Nothing. The fuse burned down, fizzled out, the stuff failed to ignite.

"Fie," said I, and stuck another piece of fuse in there. Same result.

So I took my propane torch, and gave the powder a quick bake. It took nearly two seconds of full on propane torch contact to set the stuff off, wherein it went "fffpop" and made a big fat flash as it's supposed to. Zero residue left, so I believe my ratio to be close to correct.

So I tried with the rest of my little batch, and had the same results. Fuse, poking it with a match, even sticking a little pile of black powder on top all failed to ignite the stuff but the propane torch did it.

"Sensitive," my ass!

The crystals even after grinding are a deep but marked purple color, and all the information I've been able to find on the stuff (with which I have zero experience because it's a bitch to get around here) speaks that the crystals should be charcoal grey/black. Has my permanganate gotten wet, perhaps? I believe it has.

Tossing a little pinch of the stuff into a beaker of water turns the entire mess brilliant-ass fuschia. Nothing floats on the top, nothing settles on the bottom. I don't think I have an impurity issue.

I have half a mind to try to dry my sample out at, say, 150 degrees. Literature suggests KMnO4 doesn't decompose until 240... Any thoughts?

JSTOR Article On KmnO4 Decomp (http://links.jstor.org/sici?sici=0080-4630%2819660405%29291%3A1425%3C208%3AKODOPP%3E2.0. CO%3B2-Y&size=LARGE&origin=JSTOR-enlargePage) -> "At temperatures below 150C reaction was confined to the boundaries of grains. The grain size was observed by photomicrography and used to deduce the absolute rate of the interface process."

IMO, the article seems to indicate things are relatively stable until you hit 150C so you may want to give yourself a 10C safety margin.

Otherwise, one could attempt chemical dessication with something like drierite (CaSO4). Put the Drierite in the bottom of an airtight container and place the KMnO4 in a seperate container on top of the bed of drierite. As far as i know this should be safe, although i do not know how effective, anyone out there tried this?

Well, I did some fooling around with it.

I took two samples of my KMnO4. The first I put on some filter paper and threw in my toaster oven at the lowest setting it has, which is 150 (and I imagine the answer for how accurate its thermostat is involves more than one "not very"). Three immediate observations: I was not overcome by poisonous fumes, the color of the pile of KMnO4 did not change, and no mass was lost from it. I left it in there for three hours, and figured if heat could dessicate it then the stuff was about as damn dessicated as it was gonna get.

With the second sample I threw a few commercial desiccant packs in a sealed container and left it overnight.

This morning I made three more batches, one each with the baked stuff, the dessicated stuff, and the unmolested stuff. All three performed the same: Perfectly well, but requiring more heat to ignite than visco could provide.

So I made a third batch using my un-baked, unmolested KMnO4 but adding one part of sulfur to the mixture.

Bingo!

Visco (or my torch lighter) ignites it on the spot now and it burns noticeably even faster than before.

I have no idea how sulfur will affect the stability of the mixture other than what I've read (which indicates that it's bad, though not why) and am satisfied for now.

I think I'll stick to chlorates.

I have no idea how sulfur will affect the stability of the mixture other than what I've read (which indicates that it's bad, though not why) and am satisfied for now.

I think I'll stick to chlorates.


The main worry about a sulfur + KMnO4 composition is that Sulfur can with moisture and air form H2SO3 (sulfurous acid) and maybe some H2SO4 as well...you should be familiar with the H2SO4 + KMnO4 reaction...if not it will form the very sensitive explosive Mn2O7 and a small amount of O3. Both are incredibly oxidizers and when they form they will without a doubt oxidize your Al powder and result in an ignition.

It would be very difficult to get KMnO4 + Al flash fuse sensitive...you need to add some sulfur.
try,
80: 10: 10
KMnO4: Al: S

or
6: 2 :2
if you're short on oxidizer.
all ratios in grams!

The sulfur is to lower the ignition temperature and also to help promote the formation of more gaseous products (just like with BP)

Remember your sulfur can not have any traces of H2SO4 in it, and it would be advisable to use sulfur powder that has a small amount of CaCO3 mixed in with it to minimise the possibility of accidental ignition with this flash mixture...Remember it is said to be moisture and static sensitive.

Though in saying that I have never had a premature ignition from 80:10:10 with sulfur that was 2% CaCO3...even in wet Eire.

Is sodium bicarbonate enough to do the trick? I can get calcium bicarbonate but I don't have any lying around at the moment. The sulfur I use is agricultural grade, which is 90% elemental sulfur and 10%... other crap. Probably anti-caking agents and one would hope some sort of buffer, but the bottle does not specify.

I should deliberately add a small amount of water to some of my flash to see if I can get it to ignite.

You might be able to use other things to lower the ignition point aside from sulfur... what i don't really know... organics arn't happy with KMnO4.

MgAl is a possibility... but i mean hell, if you can get MgAl bought or made, you should know better than mixing it with KMnO4.

Search for non-organic fuels and/or oxidizers that have low melting points and arn't hygroscopic or overly acidic would be my recommendation...

Is sodium bicarbonate enough to do the trick? I can get calcium bicarbonate but I don't have any lying around at the moment. The sulfur I use is agricultural grade, which is 90% elemental sulfur and 10%... other crap. Probably anti-caking agents and one would hope some sort of buffer, but the bottle does not specify.

I should deliberately add a small amount of water to some of my flash to see if I can get it to ignite.

yes it would be a good idea to test your flashes moisture sensitivity.
The agricultural grade sulfur I get does clump a fair bit and is around 2% CaCO3 (as said above).
I don't think there would be a major problem with CaHCO3 except maybe it's high solubility and (oh Yeah!) under alkaline conditions Al is IIRC fairly reactive (NaOH(aq) + Al foil for example) and KMnO4 will be reduced under basic conditions too so there may be a small possibility of an accidental ignition there...but you don't have to worry since you have CaHCO3 all you have to do is dissolve your bicarbonate in water and evaporate the solution to dryness to get pretty pure CaCO3...
check out the solubility of CaHCO3 so you don't end up boiling for hours.

I recommend dumping a gram of your Agricultural grade Sulfur into 100 ml of water and testing the pH.

Le meas.

Need to find my litmus paper for that.

Anywho, yesterday I took a .5 gram pile of my mixed flash, sulfur and all, poured out on top of my anvil and stuck a soaked cotton swab into it. I left it there all day while I noodled about with various other nonpyrotech things in my workshop, and all that happened was the Q tip turned purple from the KMnO4. I took a big old sturdy metal trash can and stuck it over the anvil figuring it'd arrest any flash or sparks if the stuff went off overnight. (The floor is concrete.)

So this morning, I took an eyedropper and squirted a droplet of water right onto the stuff. Left it there again, all day, nothing happened. Not even a fizzle. The water has mostly evaporated and left a slightly solidified cakelike lump. I put my trash can back over it and intend to leave it there until I need to use the anvil to see if the stuff ever self-ignites via moisture. I may hit it with the eyedropper again tomorrow.

Maybe I ought to hit it with the hammer and see if I can set it off that way instead. Thus far, KMnO4 flash's vaunted "sensitivity" has turned out to be a big fat bust...

The 10% of other stuff in garden sulfur as i understand it is CaCO3 and clay.

One thing I've noticed is that KMnO4 definitely ages. Over time, some of it will decay into MnO2 and K2O. After several years my big bottle of KMnO4 has gotten very slightly but progressively darker. Also, its sensitivity has noticeably decreased. When I pour some glycerol on a small pile of it, it no longer ignites spontaneously, but sort of just heats up and fizzles. I'm sure if I wanted to I could dissolve and ppt the whole batch to purify it again, but I don't really have the immediate need to do that. Anyway, just thought I would pass that possibility on. If your KMnO4 is old, it probably has the same decay problems.

I independently developed a KMnO4/Al/S flash many years ago. I found that KMnOr+Al would not ignite satisfactorily, unlike KClO3/Al. I added a small percentage of sulphur pretty much through inspiration and found that I had developed an excellent flash power. I used it until I accidentally detonated a goodly amount in my face, putting me in the hospital for the better part of a week. An 8-15-10 ratio should work fine. It was only later that I learned that I had been very lucky that the KMnO4/Al mix had not gone off spontaneously. Most chem majors I met in college were quite surprised that I had not blown myself up long before the accident. I think that I'd probably stay away from permanganates, although they will surely work.

PS: I never tried to store the prepared powder; I mixed it just before use. I did keep the KMnO4 for good periods of time without a problem.

Yeah, permanganates are very dangerous and unstable. They're also very spontanius in that you never really know how they will preform or what they will do. I'm not entierly sure why people have had problems with KMnO4/Al flash as mine always worked spectacularly in very small amounts. I'd have to say that BY FAR the KMnO4/Mg flash i made one time was the srongest LE i've ever seen.

I have no doubts or problems with the potency of the stuff once I get it lit. About a quarter gram of it wrapped up into a paper football/polumna just restrained with electrical tape enough to keep it from falling apart produces a report like a 12 gram CO2 stuffed to the gills of black powder.

I dare not, at this point, try to cram more of the stuff into anything providing better confinement until I know just how far I can push it without defingering myself (or worse). I can say it seems more powerful than my chlorate based flashes (probably due in some part to the inherent shittyness of my homemade aluminum powder) but I can't compare it to perchlorates as I don't have any. The extra oxygen obviously makes it a better theoretical oxidizer than KClO3.

I have one further concern to address, and that is that in the small sample of my permanganate I have ground up finely (with mortar and pestle) and tucked away in an airtight container I notice a distinct fishy/wet dog kind of smell whenever I open it. My original crystallized sample doesn't seem to smell like much of anything at all, but I haven't exactly stuck my head in the container and taken a deep breath. Nor do I plan to.

Is this a product of contamination, perhaps with organics? The aroma seems pretty organic to me. The effect of moisture, or just the general funk of the stuff slowly doing whatever it does in storage? I have no prior experience with KMnO4, so I have no recollection to draw on.

I've never had that problem fate....recrystallize until it's gone?

I'll give it a whirl. It could have been some contaminant from my mortar and pestle, which are less than lab grade...

Permanganate flash is one of my favorites. For a really good mix you should try,

8:2 -- KMnO4:Al (German Dark)

or

12:7:10 -- KMnO4:Al:S


The second is lovely :)
The first will do in a pinch if no S is around.

Beats the pants off chlorate flash...But still, be careful.

/AV/

12:7:10 -- KMnO4:Al:S


is lovely :)

Beats the pants off chlorate flash...But still, be careful.

/AV/
That ratio is close to 42: 24: 34
which is pretty good if you're low on Manganate VII and to me seems more economical.

I do find that the 80% KMnO4 mixes usually produce a good bit of green K2MnO4 (you'll notice if you place your flash in a white papered polumna)

I chucked a polumna into an open dumpster behind my store that'd been rained in that day. I was surprised at the amount of water droplets in there that instantly turned purple from unburned KMnO4.

Even wildly inefficient as my powder may be (and indeed, all powders may be...) those suckers are fucking loud given they've got all the confinement of a paper football.

I chucked a polumna into an open dumpster behind my store that'd been rained in that day. I was surprised at the amount of water droplets in there that instantly turned purple from unburned KMnO4.

Even wildly inefficient as my powder may be (and indeed, all powders may be...) those suckers are fucking loud given they've got all the confinement of a paper football.

What ratio were you using?
try the 42:23:34 mix next time!

Yeah they are seriously loud....for a cool shower effect I add small pieces of cannon fuse in my empty pill bottles/polumnas so they go flying after the burst...they also aid in igniting the flash as you have more than one burning fuse in contact with the mix.

I would really love if someone tested this flash mixture for friction, impact, static and moisture/ humidity sensitivity.
I've sprayed the mix with a window cleaner spray bottle which was filled with water...and apart from a slight purple puddle nothing happened...(I might get around to testing acidic rain water in the future all my tap water is fairly alkaline)
I've mixed .2g of the mix in a plastic polyethylene zip lock baggie to test for static...nothing much happened but Ireland lends to be fairly humid the whole time.

I've never heard or made KCLO4 flash powder in Ireland (apart from at Halloween bangers etc) but is the KMnO4 flash mixture on par with it?

Seems to be, other than being harder to ignite. Just as many oxygens on there, after all.