16 replies to this topic

[Deano 1]

Last night I let off quite a few fountains from various sources, some of them had what I might say micro stars in, or I could be totally wrong there, anyway I was impressed by the sound and sight of these fountain'. Mixed in with the gold sparks were small white flashes with a loud report, there were that many together it just made a very loud crackle. Does anybody know what I'm talking about and if so do you know how to make them,

[phildunford]

Last night I let off quite a few fountains from various sources, some of them had what I might say micro stars in, or I could be totally wrong there, anyway I was impressed by the sound and sight of these fountain'. Mixed in with the gold sparks were small white flashes with a loud report, there were that many together it just made a very loud crackle. Does anybody know what I'm talking about and if so do you know how to make them,

I have a very nice micro sttar forumula that does this bismuth trioxide/ nitrocellulose etc - I'll look out the formula...

[Deano 1]

Thanks Phil, I look forward to seeing it. Then I can get an order put in with Inoxia, thats if Steve stocks all the ingredients.

[seymour]

Recently I have made crackle for the first time.

I have used the formula from Passfire.

Bismuth trioxide 37.5
Copper(II) oxide 37.5
MgAl 25

Bound with NC.

I have found that it crackles very well with a lot of noise per grain. While I do not get a single crack per egg like in the fountains you describe, all that should be needed to get that happening is to tweak the MgAl size.

[phildunford]

Here's the one I use - from Lancaster:

Magnalium 15%
Copper (II) Oxide 10%
Bismuth (III) Oxide 75%

Bind with NC

Another formula (cheaper)

Is Magnalium 11%
Lead Oxide 89%

Bind with NC, although that one does not work so well for me...

[Deano 1]

Thanks for that Phil & Seymour, although I seem to be having trouble finding bismuth. Another question, can I use my homemade NC for the binder ( ping pong balls and acetone )

Edit; bismuth is on its way to my door as we speak and the copper oxide is coming from Digger

Edited by Deano 1, 08 November 2010 - 10:53 PM.

[phildunford]

Thanks for that Phil & Seymour, although I seem to be having trouble finding bismuth. Another question, can I use my homemade NC for the binder ( ping pong balls and acetone )

Edit; bismuth is on its way to my door as we speak and the copper oxide is coming from Digger

I'm pretty sure any NC would work. I use a (real & now rather rare) NC lacquer that was intended for vintage guitars & motor bike petrol tanks!

It's generally stated that any type of bismuth or lead oxide will work, but some experimentation will be required. The main reason for changing to bismuth was to reduce toxicity, but frankly we deal with many compounds which are far more dangerous than lead...

[Steve]

Also, back in the day, Bismuth wasn't so expensive.
http://www.minormeta...&site=4&lang=EN

[Deano 1]

Also, back in the day, Bismuth wasn't so expensive.
http://www.minormeta...&site=4&lang=EN

Thats an interesting website Steve, its amazing how the prices can fluctuate

[Deano 1]

I'm pretty sure any NC would work. I use a (real & now rather rare) NC lacquer that was intended for vintage guitars & motor bike petrol tanks!

It's generally stated that any type of bismuth or lead oxide will work, but some experimentation will be required. The main reason for changing to bismuth was to reduce toxicity, but frankly we deal with many compounds which are far more dangerous than lead...

I've also got some lead tetraoxide on its way too so I can do some experimenting and see which I prefere.

[dr thrust]

exactly how sensitive are they? and why

[BrightStar]

I'm pretty sure any NC would work. I use a (real & now rather rare) NC lacquer that was intended for vintage guitars & motor bike petrol tanks!

Agreed, almost any NC lacquer will work for small 'cracker granules', including ping-pong at a pinch. Larger cut dragons eggs seem to need a high solids loading of NC (up to 20%) to give the uniform smoulder then loud bang. I suspect a good quality single base smokeless powder is needed here.

frankly we deal with many compounds which are far more dangerous than lead...

The problem with lead is that it's a bioaccumalative poison so once you absorb it it's there for life. Barium poisoning on the other hand can kill, but in small doses you'll likely recover eventually as it leaves your system. Does anyone know where Antimony sits here?

[Potassium chlorate]

Antimony is a bit tricky, since it's in the same group as bismuth, but arsenic is also in that group and is, like antimony, a metaloid, and arsenic is bioaccumulative.

[Mumbles]

Wear a respirator and gloves, and you'll be fine. Red lead is so heavy and dense it doesn't really become airborne all that easily actually. Same goes for antimony trisulfide, though it does get airborne a bit more easily. Antimony is used primarily in glitters, and anyone who can mix them without respiratory protection is a stronger man than I. The charcoal really bothers my nose and throat.

I've never heard of someone requiring 20% solids loading to get a good crack. I had the best luck by adding standard 10% NC lacquer to the comp until it is kind of soupy. Stirring it around outdoors causes it to set up pretty quick if acetone is the solvent. A fan helps if you're using standard lacquer thinner which has MEK, toluene, ethyl acetate, etc to help extend work time. If it dries too much, solvent is easy to add to reconstitute. Let it evaporate to a clay-like consistency and granulate or cut. Even if I added 50% liquids, that is still only 5% ending solids.

The key seems to be getting good solid grains. There are some people who use star plates with very small holes with good success. I'd imagine the same kind of concept would also be possible via higher NC solids compared to what is necessary than to simply have solid grains. This conversation got me thinking that the screen slicing method popular with parlon bound stars (using NC instead) might be a viable way to make the good cracking type of DE. The other thing I was thinking about was Mike Swisher's method to make polverone. The grains end up significantly harder and more solid than a simple granulation. It would probably be very easy with the quick evaporating solvent. With water bound poloverone it takes hours to get it to the correct consistency.

[phildunford]

I just mix mine to the consistancy of putty, squash it down on a glass plate about 3mm thick & mark it into approx 3mm cubes with a knife blade while still soft. When hard, I run a blade underneath & break it up. From about 3 mm cubes down nearly to dust, even quite rough & ready seems to work. Add to a gunpowder type fountain and you have it!