I think I've been duped

[Shalashaska]

About 3-4 monthes ago, I ordered 8 oz. of potassium perchlorate from UnitedNuclear. Since then, however, I haven't been able to obtain any fuels besides confectioner's sugar. As a test, when I got it, I mixed it about 1:1 with the sugar and lit it. After about 10 seconds of holding the flame, it ignites when the sugar becomes molten, and burns with a light purple (not far removed from Mace Windu's light saber :D )

Recently, I made some aluminum powder with a friend's bench grinder and a chunk of aluminum from another friend who got it from the scrap bin in machine shop. When I mixed the PP with the Al Powder, it didn't ignite at all... just crackled a little bit with no light, just sound.

The only conclusions I can make so far are as follows:

a. United Nuclear (purposely or otherwise) gave me something other than the potassium perchlorate, most likely a different potassium-based oxidizer judging from color.
b. The aluminum was alloyed with some other metal, making it a drastically less efficient fuel.

Anyone got any ideas, because besides those two, I have no clue.

[tmp]

I've always held the opinion that United Nuclear is overpriced but I've never
heard of them being accused of fraud or making mistakes. The light purple
flame is correct for potassium compounds.

You said you mixed the KClO4 in a 1-to-1 ratio with confectioner's sugar.
Was this by volume or weight ? By volume is inaccurate because density
is affected by particle size. By weight, KClO4-to-sugar should work well at
a 2.5-to-1 ratio. I know that confectioner's sugar is almost floury. How
fine is your KClO4 ? What method did you use to mix them ?

Again referring to particle size, how fine is your Al powder ? In what ratio
did you mix the KClO4 and Al ? You haven't given enough information to
make an accurate determination.

[knowledgehungry]

Was it only ground by the bench grinder? If so then your powder is not nearly fine enough. You need fine mesh for it to ignite and burn well. Look up ball milling. Your PP may also need to be milled.

[Shalashaska]

The mix with confectioner's sugar was by volume, I repeated it about 2 hours ago with the same results.
My potassium perchlorate is very fine, leaving a trail behind. I'd say about the same as the confectioner's sugar, being about flour sized.

And the aluminum powder is roughly 200-300 mesh... This is also pretty depressing considering the kitchen grinder I picked up at Wal-Mart for $10 didn't do shit. :(
It's the same particle size as when I collected it from the bench grinder. Still pretty fine, though

[Evolutionist]

United Nuclear is a reputable company in my expierience. The problem as it seems to me is that Al powder has to be ground to 300- 400 mesh to be effective. United Nuclear used to sell 700 mesh for making flash powder, but I have heard that it needs to be minimally 400 mesh and the finer the better.

Also the mixture might not have been mixed thouroughly enough.

[tmp]

If you don't have a scale, get one ! Weight is the most accurate way to
determine the amounts of materials you need to mix. Volume is highly
inaccurate. There's too many variables that affect volume measure such
as compound/element density, particle size, particle shape, particle density,
etc.. As KnowledgeHungry stated, get a ball mill if you can afford to
buy or build it. If you go this route, use the search engine on this Forum.
There's a wealth of information on ball mills !

For Al powder from Al foil I came up with a rather tedious but effective
method before I had a ball mill. You have a kitchen grinder - do you mean a
blender or some other machine ?

1st, I chopped up the foil in a cheapass blender on LOW speed. Not too
much at once to avoid burning out the motor bearings. I frequently did this
in short bursts, taking the time to remove any caked-up Al from the blender
blades. BTW, use the thinnest Al foil you can find.

2nd, I ran the raw mix a few times through a hand-cranked flour mill I found
on eBay. They're much cheaper than my rock tumbler-based ball mill.
Sometimes the bastard would stick and I had to disassemble the mill and clean.
This is not a difficult task considering there is only one moving part - the crank
handle with a grinding plate attached. Don't worry. Flour mills are stronger
than they appear.

3rd, I put the mix in a piece of fine rayon cloth that I found(you guessed it !)
at Walmart. Form a ball holding the mix and shake it over a pot. Dusty Al
powder will come through rayon and settle out in the pot. What doesn't
filter out goes back to the flour mill. This Al powder is FLOUR FINE ! One
drawback is that some of that powder can get outside of the pot before it
settles. That's why I set the pot on several sheets of newspaper. Forgot
to mention - look for the rayon in Walmart's arts and crafts section.

If you can't afford the flour mill, try experimenting with the blender only.
But always use that 3rd step. BTW, there are some threads in the Forum
on using blenders. I hope this info and other info in the Forum can help.

Best Of Luck !

[Jacks Complete]

tmp, I can't give you any more rep, but I would if I could. Great post.

Skahala-boom-shakalaka, I think it incredibly unlikely your Potassium Permanganate is either impure or not what it says on the tin. The penalties for selling something like that and mis-labelling, both for shipping and storage, as well as useage, as steep.

To test it, drop a few grains into a liter of cold water. You will see a purple train stream off it as it falls, and it will dye the bowl light pink eventually. Nothing else (except some dyes) does this. If you want to test it for oxidation power, get a grain, put it on a bit of white paper, and add a tiny drop of water. Leave it for ten minutes, then rinse clear. You should find that there is a yellow burn/scorchmark left behind.

(Please someone correct me if I'm wrong, I've not had any in a long while.)

[knowledgehungry]

You may not be able to, but I am :D.

You are right with how to tell if a chemical is Potassium Permanganate but what he bought was KClO4(supposedly).

There is no reason for United Nuclear to sell you fake KClO4, they rape you with the price anyway.

The problem is either with your Aluminum or your ratio, not with the KClO4(unless it too needs to be a finer mesh)

[tmp]

He's using the perchlorate. If he was using the permanganate, I know the
reactions would procede a lot faster ! For example, his sugar mixed with
KMnO4 would ignite with a drop of water. That has to be one of the most
powerful oxidizers I've ever used. You're absolutely right about the pink
stains on glass. I've had to use HCl to get it out of my beakers. BTW, thanks
for the compliment !

[Shalashaska]

Yeah, but all this was done not to make any type of spectacular explosion, but simply to ignite. Shouldn't the Al mixture do that at least, disregarding exact ratios?

[DONMAN]

If you where just using a grinder all of your fine Al would have just oxidized. Your Al powder would consist of fine AlO3 and a slightly bigger mesh of Al with an AlO3 coating.

[defiant]

Wikipedia is your friend when it comes to flash powder:

"Generally, 70% potassium and 30% aluminum mass mix of potassium perchlorate and aluminum powder works very well. The more finely powdered the materials, the faster the reaction, and the "sharper" the flash."

Grinding aluminum on a wheel isn't a problem (other than clogging the stone or not getting a fine enough powder). The problem is that aluminum oxidizes very quickly, and finely powdered aluminum even quicker due to increased exposure. It can't be stored for extended periods unless its coated. As I recall the "coating" is an acid bath treatment of some sort. If anyone is interested in the particulars I'll dig up the file.

[Shalashaska]

I doubt that the aluminum oxidized as a result of the bench grinder... I think the picture you're getting in your head is red hot sparks flying off the grinder... It doesn't get that hot during the grinding.

[knowledgehungry]

Aluminum will oxidize in the air at room temperature, just because your Aluminum is oxidized doesn't make it unusable.

[DONMAN]

It doesn't get that hot during the grinding.

Never mind then. I think that you would get much better results with the oil and Al foil method. Thats just me.....

[defiant]

Correct, its the exposure to air that causes aluminum to oxidize - not the grinding. Grinding simply exposes surface area to oxidation.

I worked with aluminum quite a bit in the marine industry, and aluminum coating tech reps advise not to prep (i.e. grind) more aluminum than can be coated in an hour or so. Surface oxidation of aluminum occurs relatively quickly and prevents proper adhesion of primers.

This isn't to say that a little oxidation will ruin the aluminum for flash powder or energetic purposes, but that oxidation over a period of time can ruin the aluminum.

Consider also that potassium perchlorate and potassium permanganate are oxidizers. Extended storing of aluminum with potassium perchlorate (or potassium permanganate) will accelerate the reduction of aluminum to its oxide. The end result is reduced shelf life and/or strength of reaction.

[Shalashaska]

Okay, so, just as an update on this situation, about a week ago, I got my 400 mesh Al powder from Skylighter and tested it with the "potassium perchlorate," and it's almost definitely not KClO4.

I tested at first with the basic 70/30 mixture, and after that didn't work at all, I started adding KClO4, then after that didn't work, I added Al powder, which also didn't work.

I then tried the Al powder with some 100-50 mesh potassium permanganate, which went up in a flash.

As a result, I've decided not to order anything from there again, except some nichrome wire when I need it. They were overpriced to begin with, but if they f***ed up my order, then f*** em'. :)

[perrymk]

Have you tried some chemical spot tests to see if the KClO4 is pure? They're not perfect and often not conclusive but I feel can be of value for screening for contaminants. Of course ICMS would be better.

Here is the simplest chemical spot test that I have used. It's useful but has many interferences. I have two specific to perchlorate that I also use. I will point out I have been using NaClO4 but I wouldn't expect it to react too different from KClO4.

Diphenylamine Reagent
Add 4ml water.
Add 20ml concentrated H2SO4 under constant stirring.
Add 0.1g (C6H5)2NH (Diphenylamine) and stir until completely dissolved.

In a spot plate:
Add small amount of sample.
Add several drops of reagent solution.
Wait 5 minutes.

Positive: Nitrate - dark violet.
Nitrite - yellow.
Chlorate - yellow.
Iodide - purple.
Bromide - yellow.
Perchlorate - slight blue tint, slow to develop.

Adapted from
“Spot Test Analysis”
by Ervin Jungreis
John Wiley & Sons Inc.
2d Ed. 1997
page 98

and probably some other sources also.

[Charles Owlen Picket]

I had been reading this thread with interest as it progressed. The assumption was made that the individual DID have KCLO4 and that idiosyncratic elements kept if from becoming useful, etc.

I felt reluctant to offer that he should simply get a copy of Merck and find specifics of mp and solubility and test for that. But I will make that suggestion now!

"Shalashaska", you would not be the first to receive a false purchase. There was a time when some "Indian Black" Al was being sold (by various sources) that contained a VERY LARGE percentage of carbon. So much that it reflected in the overall weight as much as .25%. This was found out by someone who did not accept the face value of the product.

He was told that the method of burning paper backed foil produced carbon, etc, etc. But under a microscope he saw piss poor 325 mesh Al and a Hell of a lot of carbon. At that time dozens of people who were PGII members got their money back and were damn angry.

Falsifying what someone buys for a chemical is a very old thing. It's results can be serious in the extreme. If this happened to me; I would not let it go.
I would go to solid sources like the Merck Index and find out exactly the specifics of tests necessary for determining KCLO4; logging the result and making a bit of a fuss....if you take the time to think of what some of the substitutions in chemical falsification could lead to you may get EXTREMELY angry.