C6 +10% -20+30 MgAl MiniMine

[SharkWhisperer]

From a C8 base, the +10% metal reduces the oxidizer down to a C6 level.

 

Tested 30g comp in a 1.25" iron stargun pushed by 3.5g hot willow lift.

 

These were mostly 1/4" cut stars with 3 pressed comets 3/4" in diameter by 1/2" tall.

 

Had some star shattering from the hot lift charge, but like the final shape nonetheless. 10% large MgAl doesn't completely mask the orange firedust. More might.

 

Gotta take care with mine bursts like these with long burning charcoal comps that you don't start the ground afire from returning sparks. In that case, safest to test individual stars or comets in a well-fitting gun so you get altitude and no chance of ember return to ground level. Recently finished raining here, and fire extinguisher at the ready, so little concern with this demo.

 

 

Now for some shells and 3" mine bags...

 

[Richtee]

Pretty! So wet here no worries. Ugh.

[JeyJey]

Very nice.

What is the mesh size from the MgAl you used?

[SharkWhisperer]

Very nice.

What is the mesh size from the MgAl you used?

Tx, charcoal comps are cheap, easy, and diverse. Mesh is in the title, amigo. -20+30 mesh MgAl. Nice tight range of large(ish) particles. Smaller particles or wider ranges will give different effects. I like the uniform sizes/light output from these large particles. Makes a nice satisfying crackling sound, too, especially audible from ground level instead of a several hundred feet above.

 

Charcoal was half crummy airfloat (one good use for the junk), milled 30 min w/oxidizer, S, and dextrin, and then half +40 SYP milled for 5 min to give a range of sizes for sparks. No need for milling usually (you might get a slightly slower burn) but wanted to bust up the granulary SYP coal a little bit.

 

MgAl hand-mixed in afterwards.

 

Bound with 70% IPA, mixed and let incubated in a ziplock for a half hour before cutting/pressing, to allow dex to fully activate. I like IPA for fast drying, and the 30% water is enough to activate the dextrin, but it helps to give it some time to do so. Pure water is cheaper and typically used (maybe with 20-25% alcohol to reduce surface tension and speed wetting) but I'm lazy when it comes to drying times and the volumes/cost of IPA are not large for a half kilo batch of stars.

 

If you're pressing and cutting charcoal comps the same day, helps to wet them separately. Can usually get away with 10% moisture or so for pressing (these are hand-rammed), but need more moisture for making a patty for cuttiing (perhaps 20%? I just eyeball it because it will change depending on charcoal characteristics). If you press these putty comps then excess liquid will be squeezed out & you know it's too much. 70% IPA isn't going to dissolve/remove much KNO3 at all at ambient temps, so this is more a sloppiness concern than a comp-degrading concern.

 

No prime necessary. You show charcoal stars a photograph of a match and they spontaneously ignite.

Edited August 16, 2021 by SharkWhisperer

[JeyJey]

It would be interesting to add some delay agent as NaHCO3 or Sodiumoxalate to create a long lasting glitter.

 

Do you want to try it? I'm curious about the result.

[SharkWhisperer]

It would be interesting to add some delay agent as NaHCO3 or Sodiumoxalate to create a long lasting glitter.

 

Do you want to try it? I'm curious about the result.

Curiosity is good. It'd be excellent if you gave it a try and reported back with your findings. You'd probably want to start your experimenting with proven glitter comps that use aluminum or MgAl finer than the large(ish) -20+30 used here, and make small thoughtful adjustments to those formulations to suit your tastes.

 

You don't need anything fancy to make charcoal stars--easy enough afternoon project with just a kitchen screen and water. Maybe a coffee grinder. Inexpensive, too. Largest cost is typically for added metals.

 

Just be careful with your testing--charcoal's sparky and so are metals. And if you try to delay/extend the burn, there's a good chance you'll have hot sparks hitting the ground. So keep first tests small and send them high to learn your comp's burn characteristics/length of time afire. And have a good fire extinguisher or garden hose (turned on) close by, just in case.