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#646 knackers

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Posted 10 January 2009 - 11:02 PM

The only problem is I cannot find a supplier of dark aluminum accept at one place were it is 10 pounds for 100g of the stuff which is pretty expensive. I have loaded up a tic-tac container with 10g of my shit flash all celataped up, hopefully it will work but wont build my hopes up. Thanks for the help up to now, I do not have a ball mill but do have a vibratory mill and I assume coins would work as media being that they are made from steel.



try this site,, " northstarpyro.com " i buy my products here and get great products and range with just as good service, although at the moment the $ exchange rate prohibits me at this stage,

i buy the indian blackhead Al powder, for about $20 au per lb ( about 10 english pounds ) + postage

#647 digger

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Posted 10 January 2009 - 11:23 PM

Why do you think most places quote Eckhart 5413-H as 3 micron when Eckhart list it as less than 45 micron?
Phew that was close.

#648 knackers

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Posted 11 January 2009 - 01:07 AM

Why do you think most places quote Eckhart 5413-H as 3 micron when Eckhart list it as less than 45 micron?



My guess is,, how is the aveage joe going to know what micron it is ? plus its saleability is increased with a finer grade,,
and technicaly < 45 microns can be anywhere between 1---> 44 microns, so misrepresenting their product is possible,and not illegal,
the indian blackhead i buy is marketed at 4--->5 micron, i have no idea what it is therefore have to trust the supplier, whatever it is i am more than happy with it, ( 3 grams open on a flat test plate is unbelievably fast ) if i had to guess its speed.... a fraction of a nano second", you can feel through sound an almost det-nation, i have used, 5 grams and 10 grams as burst charges and the star projection is fantastic, although my glitter stars work great it seems to blow my colored stars blind, ( need to work on a prime , any advice would be welcomed ) i did do a thunder burst by mixing 10 gram lots of 70:30 x 40 grams in a 2.5" can shell on a 3 lb rocket and it was exactly that, " thunder" with my own made kclo4 and puchased indian black....
i must also say i am terrified when ever i mix it and don't do it as much as i thought i would, ( sort of a been there done that, know what can happen and don't really want to use it much anymore, But still do )

i can't emphasise enough the advice given here by others on the dangers of flash is invaluable, "" Curious new comers take heed !!

if this stuff doesn't kill you in an accident it will blow your body parts off !

#649 Mumbles

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Posted 11 January 2009 - 09:21 AM

I'd venture that 3 micron is the average size, while -45 micron is the particle size. 45 micron is the maximum produced. It all passes a 45 micron screen theoretically. There is obviously a gradient of different particle sizes produced as it comes from a mechanical method.

#650 digger

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Posted 11 January 2009 - 10:48 AM

I agree these aluminiums are good stuff I use Super-H myself, with a little titanium sponge added it will self confine at low single figure gram quantities.

Yes all powders have a particle size distribution, very often fitting a normal distribution curve and clearly the 45 micron represents the d100 percentile.

However all I was trying to point out is that you may need to take the particle sizes listed by sellers with a pinch of salt as they probably don't have the equipment to measure the size distribution and Eckhart do no give it on their data sheet. Basically it would appear that people have got obsessed with getting the smallest possible listed particle size and not with the performance of the product. I assume this is why some suppliers list the metals as they do.

I have heard of 1000 mesh sieves, but the main suppliers lab sieves only go to 600 mesh or around 20 microns before different technologies are employed, there simply are not enough sieves in that range to work out a distribution curve and stokes law would need careful consideration due to the particle shape of these aluminiums.

It is certainly possible to work out the size distribution of these aluminiums, but I have not seen it done by a reputable source, BUT if anyone knows where this data can be found please let me know as it would be very interesting.
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#651 Potassium chlorate

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Posted 11 January 2009 - 10:56 AM

Not to be rude, but I guess most amateur pyrotechnicians outside the English speaking world know that a micron is 1/1000 of a millimeter. ;)
"This salt, formerly called hyperoxymuriate of potassa, is
used for sundry preparations, and especially for experimental
fire-works."

Dr. James Cutbush

#652 digger

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Posted 11 January 2009 - 11:02 AM

Not to be rude, but I guess most amateur pyrotechnicians outside the English speaking world know that a micron is 1/1000 of a millimeter. ;)


Yes, but what do you mean by that?
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#653 Potassium chlorate

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Posted 11 January 2009 - 11:06 AM

Yes, but what do you mean by that?


Someone said that the "average Joe" doesn't know it. I'm not sure of that. Micrometer is a pretty well-known term in Sweden, for instance.
"This salt, formerly called hyperoxymuriate of potassa, is
used for sundry preparations, and especially for experimental
fire-works."

Dr. James Cutbush

#654 Arthur Brown

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Posted 11 January 2009 - 11:19 AM

Even though better equipped pyros may know what a micron is,they possibly cannot determine the size of particles in that region. So a vendor could write 5, 15 or 50 micron on a label and we would likely have to trust them. With all powders having a particle size distribution it is even harder to determine the accuracy of the "Label value"
http://www.movember.com/uk/home/

Keep mannequins and watermelons away from fireworks..they always get hurt..

#655 digger

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Posted 11 January 2009 - 11:20 AM

Someone said that the "average Joe" doesn't know it. I'm not sure of that. Micrometer is a pretty well-known term in Sweden, for instance.


Fair enough, it is certainly is a well known term to any scientist or engineer. I thought most of the world was metric now with the notable exception of America.

I do allot of work for one of our American sites and it is a real pain as I end up converting from imperial units to SI (as using imperial requires a few extra terms in some equations) and then back to imperial to give them the answers.
Phew that was close.

#656 knackers

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Posted 11 January 2009 - 11:58 AM

Someone said that the "average Joe" doesn't know it. I'm not sure of that. Micrometer is a pretty well-known term in Sweden, for instance.


i think you may have misread/understood what i wrote,,

i didn't say the aveage joe doesn't know what a micron is, i said what micron it is,, unless you have the apparatus to measure the size, ( and i highly doubt most pyros have a micrometer at the ready ) then you are at the discrection of the supplier,

#657 pyrotrev

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Posted 11 January 2009 - 12:30 PM

I'd agree that 45u is the max. particles size, but whether the 3u figure is a minimum, mean or median particle size of the rest of it I don't know. I managed to get a full particle size analysis of an atomised alumnium that was sold as -150 mesh, and from memory 99% of that was -325mesh, with most lying between -400 and +900, something about 650 being the most plentiful.

Edited by pyrotrev, 11 January 2009 - 12:33 PM.

Trying to do something very beautiful but very dangerous very safely....

#658 Potassium chlorate

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Posted 11 January 2009 - 05:16 PM

i think you may have misread/understood what i wrote,,

i didn't say the aveage joe doesn't know what a micron is, i said what micron it is,, unless you have the apparatus to measure the size, ( and i highly doubt most pyros have a micrometer at the ready ) then you are at the discrection of the supplier,


OK. Yes, you are right. A microscope or very strong magnifier glass would be needed to figure out how accurate the suppliers' "facts" actually are.

Edited by Pyroswede, 11 January 2009 - 05:17 PM.

"This salt, formerly called hyperoxymuriate of potassa, is
used for sundry preparations, and especially for experimental
fire-works."

Dr. James Cutbush

#659 Potassium chlorate

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Posted 11 January 2009 - 05:22 PM

I'd agree that 45u is the max. particles size, but whether the 3u figure is a minimum, mean or median particle size of the rest of it I don't know. I managed to get a full particle size analysis of an atomised alumnium that was sold as -150 mesh, and from memory 99% of that was -325mesh, with most lying between -400 and +900, something about 650 being the most plentiful.


K*t*n for instance says that his German Black is "3 microns", but he doesn't say whether it's average or minimum size. It's most likely not maximum size. On the other hand he states that 99.3% of his KClO4 is 10-40 microns, which makes it pretty clear what he means, if it's true.
"This salt, formerly called hyperoxymuriate of potassa, is
used for sundry preparations, and especially for experimental
fire-works."

Dr. James Cutbush

#660 mike_au

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Posted 11 January 2009 - 11:36 PM

if you want to mill your aluminium fine enough, ...it needs to be done in an oxygen deficient enviroment


Isn't the whole problem with it becoming pyrophoric caused by the absence of oxygen in the milling container preventing the creation of the Al2O3 layer that would normally protect the Al (and therefore when it is eventually exposed to oxygen *all* of the exposed Al oxidises at the same time)?

I would have thought that if you could keep a small amount (21% or less) of oxygen present in the jar while milling the Al would produce it's protective layer as it is milled and you wouldn't have a problem. Isn't that why you are supposed to open the jar every few hours?




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