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Aluminum Powder 30micron


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Quick question regarding some Al powder I have. I bought this stuff many years ago and didn't take note of the "type" other than it's 99.5% purity and it is 30 microns. I'm wondering if it's coated in something. It's kind of dull not shinny at all and has a chalky look to it. I know it's Al because when I first bought it I mixed a gram of it with some HCL, and it produced hydrogen but what does Al coated in stearin look like? Does a stearin coating affect it's reactivity in any of the comps? And lastly, what's the equivalent mesh size for 30 micron, or is too small for use in most comps? Any help would be great.
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Does a stearin coating affect it's reactivity in any of the comps? And lastly, what's the equivalent mesh size for 30 micron, or is too small for use in most comps? Any help would be great.

I don't think it won't affect compostions. 30 microns Al can be used in stars, fountains comp, but it wont give long tails or alot sparks. Also comps that includes stearin is hard to bind well.

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It's pretty easy to tell if it's coated with stearin. If you rub the Al between your fingers, it will be sort of greasy, and it will also smell like crayons. I've only seen flake aluminums coated with stearin, so they have their own unique look.

 

From the sounds of it, you have atomized Al. What you have will be pretty good for glitters I imagine. It can be used in plenty of other formulas too.

 

At a certain level mesh stops to really have real meaning. This stuff is around the borderline where this becomes true. Micron is defined by actual particle size of a material. Mesh is defined by a screen in which the material will pass. The actual particle size is determined by both physical size as well as the diameter of the wires used to make the screen which decrease the opening size beyond the theoretical mesh. For instance a 4 mesh screen actually has openings closer to 0.2" instead of 0.25".

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Just a thought, I tried making a small batch of thermite a long time ago using the stuff I have described here and it didn't work out too well..That said, does flake aluminum make for better thermite than spherical, assuming the Al is of the same relative size?

 

And I'm glad someones giving input on it being spherical because I was really hoping to try out some glitter stars and was worried that I was going to have to buy some different Al. Thanks!

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I'm starting to wonder about some of the issues people seem to have with thermite. I've never had a problem, even using materials coarse enough to visually see. I wonder if some of the issues are due to too fine of material. While fine materials should react faster, it also tends to have higher thermal conductivity which could make it harder to light.

 

Flake Al tends to react faster in compositions than spherical of similar size. Despite regularly being coated, it does still have a much higher surface area.

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Yeah, it seems counter-intuitive but that does make sense. I'll have to try it out again at some point.
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