23 replies to this topic

[Demented Ferret]

Well...I recently purchased some microfine aluminium powder, is there any chance it is TOO fine? I've attempted a few experiments, but with no avail.

I was just wondering, due to aluminium's tendancy to oxidise, would it do so damn quickly that it becomes virtually unreactive?

[dfk]

There Isn't really an answer to your question, there are all shapes and sizes of Al in many different comps.
It all depends on your desired effect and of course if you had one, the particular comp you were working with.


Al can and react with certain chemicals, mainly nitrates. Most comps that contain reactive chemicals include some type of buffer as well. Like I said it all depends on what your working with.
Al does oxidize and, it can be a bad thing but I have herd of situations were it is actually desired. Al with some oxide on it is supposed to delay the reaction in glitter giving a better or longer trail.

Marcus

[BigG]

There is no such thing as too fine. Very fine aluminium (3 micron, which I don't believe your powder is) is a very desirable item. It is even restricted in the USA (well, many suppliers will not sell it unless you have proper papers...)

Edited by BigG, 12 March 2004 - 11:38 PM.

[dfk]

Actually Even 2 micron dark AL is still available but theres a one pound a year limit.

Marcus

[Demented Ferret]

Well, I'm not an expert on Al Powder and I doubt I have anything above a law of some form. Just, being the first metal powder I've had, as opposed to fine granules it seems incredibly fine. If you could advise some experiments I could do with the powder to determine it's authenticity I'd be pretty happy.

I've tried making a Pot. Chlorate flash powder (with very small amounts, and very safely - don't worry, I'm sane ) with a pinch of sulphur. The ignition of the compound was exactly the same as the Chlorate alone.

I've also attempted making a flash powder with Pot. Nitrate - same results.

[BigG]

Lucky, you did not manage to get flash working, because 5g will remove a finger or two if you try to ignite it at close range.

First, flash works only with very fine powder (nothing above 12 micron). The fact that you assume that ?it looks therefore it is? is very wrong. 71 micron also looks very fine, and it?s absolutely useless for flash.

Please, make flash your last priority. Even experience pyrotechnics treat it with extreme respect. There are many things you can try first.

Generally, such ?by the way? posts can get you in trouble with moderators. Read the forums carefully, you will see it very well.

[Demented Ferret]

Eh? I've read the 'Forum Rules', and so far I've pretty much abided by every one of them.

Anyway, cheers for the info - it was sold to me as 'microfine' so I presumed it'd be up to the job. Is there any way to find out the grading using a microscope?

- About the flash powder, I prodded the 'ingredients' around with a broomhandle (how very proffesional of me ), I've heard of all sorts of stories involving stitches and dismemberments, and I don't feel like being appended to the story book...

[BigG]

No, you haven?t broken the forum rules. But your posts (mixing Chlorate with sulphur, attempting to test aluminium by making flash, mixing fine metal with chlorate) suggest you need to read a bit more about safety procedures when working with pyrotechnic compositions. The reason this is frown upon is because some beginner might try to copy it. The only way to mix Flash is by the diapering method. The only way to make flash is with potassium PERchlorate. Chlorate will make this am even more dangerous composition then what it is.

To check the size of your particles you will need either electronic microscope (the kind that can modify by many thousands), or using shives. For the amateur, both are difficult (shives for 12 micron and lass cost a small fortune) and therefore technically you really will have a problem checking it out. My suggestion is to only buy from reliable seller that can tell you mesh size. For what it worth, you can probably use it in fountains and stars that call for aluminium in the 200-350 mesh area.

Hope this helps.

BigG

[Demented Ferret]

Ah, thanks, that helps. I'll probably make my way around to some fountains after I've got a few more 'bits' in.

I understand your concern, I've read a lot about the safety of the compounds/chemicals I use, but I didn't contemplate the safety of other users.

If you could PM me a reliable retailer, that'd be great - as I'm finding great difficulty doing so. If not, just ignore this post.

Edited by Demented Ferret, 13 March 2004 - 12:28 AM.

[Yugen-biki]

I foud out the hard way that atomized Al (>80 ?m) does not produce flash! Sulfur does not help to big Al mesh. By testing the Al in flash as you have done proves the mesh to be to big.

I use 25 ?m (+- a few ?) bright Al and it works good (oil coated). BigG --> First, flash works only with very fine powder (nothing above 12 micron)<--. How come my works? I use perchlorate and the reaction is very fast. If you get any of the Al on something it becomed all silvery and it?s impossible to make out any particles.

[Demented Ferret]

Hmmm...I'll have to get myself round to making some perchlorate, still, it's damn expensive.

[Richard H]

I use 25 ?m (+- a few ?) bright Al and it works good (oil coated). BigG --> First, flash works only with very fine powder (nothing above 12 micron)<--. How come my works? I use perchlorate and the reaction is very fast. If you get any of the Al on something it becomed all silvery and it?s impossible to make out any particles.

Just how fast is it? There is distinction to be made between good and inferior flash powder. Both will make a hell of a noise given the chance. The chinese use cheap bright powders but it just does not compare to true dark pyro.

[adamw]

To me there is no 'good' and 'bad' flash powder. There is a powder for every use. I.e. - I use 'bright' aluminium flash for articles that can't use a BP break and where you dont want the stars being turned into dust. Dark pyro also has its uses, most notably for making reports. But you can also use a different ratio of KCLO4/Al when you want a different effect from your flash.

[willd]

ive seen some flash composition that use pottasium chlorate instead of pottasium perchlorate. there are some in the pfp database is this dangerous or is there some other reason for this