Is 250 mesh uncoated aluminium powder suitable for flash powder? If not, would 450 mesh atomised powder be adequate? I am intending to make potassium chlorate based flash.
thanks
Aluminium powder for flash
Started by jcow, Nov 06 2006 11:11 PM
12 replies to this topic
#1
jcow
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Posted 06 November 2006 - 11:11 PM
#2
sizzle
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Posted 06 November 2006 - 11:54 PM
Is 250 mesh uncoated aluminium powder suitable for flash powder? If not, would 450 mesh atomised powder be adequate? I am intending to make potassium chlorate based flash.
thanks
1. Do NOT attempt to make Potassium Chlorate based flash, it is way too sensitive. The safest (but still not safe) flash is 70/30 Potassium Perchlorate/Aluminium.
2. Flash requires flake Aluminium, it is difficult to make flash with spherical Aluminium, the best type to would be Dark German Flake.
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#3
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Posted 07 November 2006 - 12:44 AM
Now, this is interesting and I wonder if anyone has an answer...
Last week on the run up to Nov 5th, I was running short of aluminium for some fountains that I was making. Now I thought I would try a process that I read on here, but not tried before. That was the process of salt in a liquidiser and adding aluminium foil. (Basically, the salt is just there to transport the balls of scrunched up foil down to the cutting blades and so get chopped into fine bits)
After dissolving the salt away in hot water and filtering it, I found some very nicely fine aluminium particle left behind. (And a reasonably amount for little work!)
After washing and drying it, I ball milled it for about 3 hours using some steel nuts as the milling media. (I also opened it up every hour to let some air in to allow some oxidation to take place.
After 3 hours of milling, it was getting late and I turned it out onto some paper and left it overnight. A quick inspection showed that I had extremely flat flake pieces slightly less than 1 mm across and light dull grey in colour. (I thought with some further milling, I could get this down to usable fountain size at least if not even smaller.
In the morning, I looked at it again and found that some of the flakes had turned a VERY dark grey (almost black)
I left it for a further day on the paper and by next morning, even more flakes had turned dark. 
Has this happened to anyone else?
Mild oxidation is always present on aluminium but is usually a light grey/white deposit. So what can this very dark grey over time be?
I did try a bit in a fountain but it wasn't very good at all.
Any ideas?
Last week on the run up to Nov 5th, I was running short of aluminium for some fountains that I was making. Now I thought I would try a process that I read on here, but not tried before. That was the process of salt in a liquidiser and adding aluminium foil. (Basically, the salt is just there to transport the balls of scrunched up foil down to the cutting blades and so get chopped into fine bits)
After dissolving the salt away in hot water and filtering it, I found some very nicely fine aluminium particle left behind. (And a reasonably amount for little work!)
After washing and drying it, I ball milled it for about 3 hours using some steel nuts as the milling media. (I also opened it up every hour to let some air in to allow some oxidation to take place.
After 3 hours of milling, it was getting late and I turned it out onto some paper and left it overnight. A quick inspection showed that I had extremely flat flake pieces slightly less than 1 mm across and light dull grey in colour. (I thought with some further milling, I could get this down to usable fountain size at least if not even smaller.
In the morning, I looked at it again and found that some of the flakes had turned a VERY dark grey (almost black)
I left it for a further day on the paper and by next morning, even more flakes had turned dark. Has this happened to anyone else?
Mild oxidation is always present on aluminium but is usually a light grey/white deposit. So what can this very dark grey over time be?
I did try a bit in a fountain but it wasn't very good at all.
Any ideas?
Edited by Shrubsole, 07 November 2006 - 12:46 AM.
#4
jcow
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Posted 07 November 2006 - 11:55 PM
Ok, thanks for the advice guys. perhaps i'll stick to chlorate and charcoal for reports. Is it possible to obtain flake aluminium in the UK? i looked on inoxia, and they only stock atomised powder.
#5
sizzle
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Posted 08 November 2006 - 12:06 AM
Ok, thanks for the advice guys. perhaps i'll stick to chlorate and charcoal for reports. Is it possible to obtain flake aluminium in the UK? i looked on inoxia, and they only stock atomised powder.
I believe HobbyChem stock flake Aluminium, apart from that I don't know of another source to the public in the UK. When you start getting more into pyro and start to meet new members of the society, you'll soon find a source.
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#6
Mumbles
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Posted 11 November 2006 - 05:44 AM
I'm not entirely sure how to explain the black surface. My best guess would be that the surface became pitted or scratched to a fair extent from the milling. The uneven surface, no matter what color the oxide is, a thin layer will reflect a black color due to the extreme scattering of light.
#7
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Posted 12 November 2006 - 12:58 AM
I'm not entirely sure how to explain the black surface. My best guess would be that the surface became pitted or scratched to a fair extent from the milling. The uneven surface, no matter what color the oxide is, a thin layer will reflect a black color due to the extreme scattering of light.
Yes it was very strange as it wasn't like it when it came out of the ball mill, but started turning black/dark grey flake by flake over time. So it must have been some sort of oxidation taking place, but I haven't heard anyone mention it on here before, so I was wondering if it was just me!
I'll try a new batch next week and see if it does the same.
#8
Mumbles
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Posted 15 November 2006 - 03:49 AM
Milling my Al always gave me a dark or black powder. However it was black coming out of the mill. I have a black rubber mill jar. I always figured it was from that or some minor BP or charcoal contamination.
#9
GBthriller
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Posted 15 November 2006 - 05:30 AM
Makes me wonder if getting your Al that wet caused the problem. What was the purity and PH of your water? Any of you chemists out there? What could the NaCl have done to it?Yes it was very strange as it wasn't like it when it came out of the ball mill, but started turning black/dark grey flake by flake over time. So it must have been some sort of oxidation taking place, but I haven't heard anyone mention it on here before, so I was wondering if it was just me!
I'll try a new batch next week and see if it does the same.
#10
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Posted 15 November 2006 - 01:18 PM
Both interesting replies there.
You say that you POWDER was or is a;way black when it comes out. Mine wasn't what I would consider a powder by that time as it started as finely shredded after being liquidised, and then had only been Bill Milled for 3 hours. (Which I hear is no time at all for aluminium making) I also stopped it every hour to let some air get in for safety reason. So basically, after that, it was about 1mm flakes. So maybe it does or is meant to go black over time and you only see that when you finally remover yours as a powder. (How long do you mill yours for to get it to powder?)
Water: Well it was our normal tap water and that is known to be very hard as Kent is mostly chalk, so that could well have something to do with it. Also, I wonder if the salt that I was liquidising it in had any effect? I did wash it and drain it quite a few times to make sure that all the salt had been removed??? Maybe if I used a less active media than salt to carry the foil around the liquidiser? Flour? Any cheap, unreactive powder will do as it's only there to carry the Aluminium around and past the cutting blades.
I hope I get some time this week to do another batch and long enough to take it down to a fine powder.
I hope it works as this does yield quite a lot of flake aluminium for little effort.
You say that you POWDER was or is a;way black when it comes out. Mine wasn't what I would consider a powder by that time as it started as finely shredded after being liquidised, and then had only been Bill Milled for 3 hours. (Which I hear is no time at all for aluminium making) I also stopped it every hour to let some air get in for safety reason. So basically, after that, it was about 1mm flakes. So maybe it does or is meant to go black over time and you only see that when you finally remover yours as a powder. (How long do you mill yours for to get it to powder?)
Water: Well it was our normal tap water and that is known to be very hard as Kent is mostly chalk, so that could well have something to do with it. Also, I wonder if the salt that I was liquidising it in had any effect? I did wash it and drain it quite a few times to make sure that all the salt had been removed??? Maybe if I used a less active media than salt to carry the foil around the liquidiser? Flour? Any cheap, unreactive powder will do as it's only there to carry the Aluminium around and past the cutting blades.
I hope I get some time this week to do another batch and long enough to take it down to a fine powder.
I hope it works as this does yield quite a lot of flake aluminium for little effort.
#11
Mumbles
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Posted 21 November 2006 - 09:20 PM
Flour couldn't be dissolved off though. How about sugar? I believe people tried this, but with the result of a sticky mass of Aluminum. One medium that worked quite well was cooking oil. It is more viscous than just water so the Aluminum is resisted more allowing it to be shredded finer than with water. One allows the suspension to settle, and decants as much as they can. Then filter through a coffee filter. Some washing with dish soap should remove the last traces of oil.
To the sodium chloride. It acts as an electrolyte allowing water to react with the metal more easily. Chloride is a fairly corrosive ion as it turns out from small amounts of HCl being formed.
If you read mypost on coating of magnesium and the chemistry and mechanisms behind it I do suggest adding some electrolytes for more efficient and thorough coating.
To the sodium chloride. It acts as an electrolyte allowing water to react with the metal more easily. Chloride is a fairly corrosive ion as it turns out from small amounts of HCl being formed.
If you read mypost on coating of magnesium and the chemistry and mechanisms behind it I do suggest adding some electrolytes for more efficient and thorough coating.
#12
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Posted 21 November 2006 - 10:33 PM
Flour couldn't be dissolved off though. How about sugar? I believe people tried this, but with the result of a sticky mass of Aluminum. One medium that worked quite well was cooking oil. It is more viscous than just water so the Aluminum is resisted more allowing it to be shredded finer than with water. One allows the suspension to settle, and decants as much as they can. Then filter through a coffee filter. Some washing with dish soap should remove the last traces of oil.
To the sodium chloride. It acts as an electrolyte allowing water to react with the metal more easily. Chloride is a fairly corrosive ion as it turns out from small amounts of HCl being formed.
If you read mypost on coating of magnesium and the chemistry and mechanisms behind it I do suggest adding some electrolytes for more efficient and thorough coating.
Or even using cooking fat? Could be easily melted off then the aluminium washed.
#13
bonzoronnie
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Posted 04 December 2006 - 08:22 PM
Now, this is interesting and I wonder if anyone has an answer...
Last week on the run up to Nov 5th, I was running short of aluminium for some fountains that I was making. Now I thought I would try a process that I read on here, but not tried before. That was the process of salt in a liquidiser and adding aluminium foil. (Basically, the salt is just there to transport the balls of scrunched up foil down to the cutting blades and so get chopped into fine bits)
After dissolving the salt away in hot water and filtering it, I found some very nicely fine aluminium particle left behind. (And a reasonably amount for little work!)
After washing and drying it, I ball milled it for about 3 hours using some steel nuts as the milling media. (I also opened it up every hour to let some air in to allow some oxidation to take place.
After 3 hours of milling, it was getting late and I turned it out onto some paper and left it overnight. A quick inspection showed that I had extremely flat flake pieces slightly less than 1 mm across and light dull grey in colour. (I thought with some further milling, I could get this down to usable fountain size at least if not even smaller.
In the morning, I looked at it again and found that some of the flakes had turned a VERY dark grey (almost black)
Has this happened to anyone else?
Mild oxidation is always present on aluminium but is usually a light grey/white deposit. So what can this very dark grey over time be?
I did try a bit in a fountain but it wasn't very good at all.
Any ideas?
It would help if I actually put some text into this reply.
As a marine engineer, It would be my guess, the salt you used to do the initial grinding has embeded itself into the microscopic pores in the aluminium foil.
It is not uncommon for aluminium to turn black after exposure to salt followed by water
Edited by bonzoronnie, 04 December 2006 - 08:31 PM.
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