633 replies to this topic

[al93535]

Has anyone here ever used rifle primers for the cores of stars? For the effect of having the star burn out and then exploding the primer.

[RegimentalPyro]

Has anyone here ever used rifle primers for the cores of stars? For the effect of having the star burn out and then exploding the primer.

Dragons eggs are often used as star cores to give exactly the effect you are looking for. Small dragon eggs can also be used to give a nice crackle effect as well.

[Phoenix]

I've read references to this practice on rec.pyrotechnics. You might find some info in the Google archive.

[BigG]

Has anyone here ever used rifle primers for the cores of stars? For the effect of having the star burn out and then exploding the primer.

I first saw the idea at David Blaser. He suggested using primers to avoid the need of messing about with lead compounds that are both toxic and sensitive. The suggestion sounds very good for the hobbyist who wishes for the extra safety.

Since then, the discovery of the possibility of using bismuth rather then lead has put back dragon eggs onto the frame. Those are more expensive, but are not toxic and consider to be considerably safer then the lead counterpart. They also make a better sound and effect then the primers ? still ? a very valid option.

Good readings on the subject are David Blessers Round Stars & Shells and Pyrotechnica XIV - C. Jennings-White's "Lead-Free Crackling Microstars".

Enjoy.

[rooster]

I was wondering, while we are talking about crackling effects...

Does anyone know a good procedure on how to make crackling cores(explosive cores)? Not with the pistol primers or dragons eggs. I seem to believe I read somewhere that larger microstars(>5mm) don't work as the smaller ones, but rather break up to more smaller crackles(?).

The (shimizu) flash core I think does not have a report. It is only a flash, I think. And the chinese's way to do it with paper and chlorate/realgar comp is way too dangerous for me(and I don't have realgar).

Of course you can add salutes to the shell, but thats not really the effect I after...

[al93535]

So how about a prime mix I just used. Potassium perchlorate 70%, airfloat charcoal 10%, 325 mesh al 14% and german dark 6%? Just a light layer over the primer with the comp rolled onto it? By the way, what do you guys use as a prime for a perchlorate star thats kind-of hard to light? I just tried the mix above and will see how it fares. But I would like to save on the dark aluminum if I could.

[adamw]

Personally I don't like the idea of rolling on primers! Suppose you were to drop a finished star and it just happened to go off. What about if a piece of foreign material were to fall in the star roller while you were rolling them, hitting the anvil of the primer and setting the batch off! What about the chemical compatibility of the lead styphnate etc and the chemicals in the star comp??!

[alany]

By the way, what do you guys use as a prime for a perchlorate star thats kind-of hard to light?

I usually use weak meal (basically greenmix) + 5% fine Al flake.

7:2:1 Potassium Perchlorate, Aluminium, Red Gum with meal over it will ignite just about anything especially if you use Magnalium or dark Aluminium. It burns like flash loose unfortunately and it is a little bit hard to light itself so you need to prime over it with greenmix or meal to be 100% sure.

[warrenizer88]

Has anyone considered using silicon in a primer comp? It stays hot for longer, after the BP prime is finished burning.



warren

[Flashy]

Primers are very insensitive! I have tested this before. They are in a sealed metal case so compatablilty is no issue. I have shot primers into a brick wall from a sling shot and they just bounce back at me. I have also tried whacking one with a hammer which took one heck of a hit to go off. Yes I had ear muffs on, goggles and I covered myself in a few towels so I wasn't exposed apart from my leather gloved hand.

Read the side of a box:-

WARNING - Primers may explode if subjected to impact, shock, or intense heat. Store in original factory container only. Primers in bulk are capable of mass explosion.

Just because one or two didn't go off when subjected to the tests you carried out, it doesn't mean you will always be as lucky.

Edited by Flashy, 06 February 2005 - 01:08 PM.

[BigG]

Read the side of a box:-

WARNING - Primers may explode if subjected to impact, shock, or intense heat. Store in original factory container only. Primers in bulk are capable of mass explosion.

Just because one or two didn't go off when subjected to the tests you carried out, it doesn't mean you will always be as lucky.

I agree with your general note - however, Bleser seem to have looked at the two, and research them, and while primer are sensetive, they seem to be considertly less sensetive then lead based crackling stars, as well as less toxic, and it seem like the metal casing does stop any incomptibility - but again, treat it all with due respect. it is worth while to understand what is that metal casing made of, to remove any questions about incomptibility.

[RegimentalPyro]

A most beautiful deep ruby red. Burns bright!

Ruby Red Rocket Comp

Strontium Nitrate 50
Potassium Perchlorate 8
Parlon 18
Magnesium/Aluminum, 275 mesh 12
Charcoal Airfloat 5
Sulfur 5
Red Gum 2
Dextrin +5

I pre-milled everything that wasn't already dust, or metal - before mixing via screening. Can be made into stars, or rocket cores.

Sourced from an article written by Pyro Polock for Skylighter.