37 replies to this topic

[portfire]

LOL have a look on the for sale page of my website its been there ages

LOL, git. I checked your site the other day aswel, missed it

[Mnemotron]

7% Si in meal is usually quite enough. It easily sets fire to stars, trees, jeans, boots...

Been there, done that, still have the scorch marks

Can i use sulfurless BP + 7-10 Si or MgAl fr priming my chlorate based star?

[seymour]

You can use Si, though usually Chlorate stars are much more ignitable than perchlorate ones, so the Silicon is probably quite unnecessary.

I would be less comfortable using Sulfurless BP + MgAl. You've probably heard of the nitrate/Aluminium reaction. Magnalium, being 50% Aluminium counts, and because it's alloyed with Magnesium, it's more reactive.

When Nitrates react with Aluminium, ammonia is produced, as I'm sure many of us are aware from experience!

Ammonia is incompatible with chlorates in quite an extreme way, since Ammonium chlorate can be produced.

So not out of fear of the nitrate/Aluminium 'incompatibility' which everyone mixes, because it can be made stable enough to work, but out of fear of the resulting Ammonium/chlorates incompatibility I advice everyone to avoid the mixture of nitrates, chlorates and Al or MgAl.

Finally, why don't you use a chlorate/charcoal prime, like H3, or perhaps with a small quantity of resin. I am aware that many people fear the contact between the chlorate star and the BP in fireworks, but this is not as dangerous as many people believe, plus it is very safe when using the stars in shells where H3 is used as the burst, the logical option to me.

Edited by seymour, 17 December 2010 - 02:34 AM.

[BrightStar]

BP primes for chlorate stars were used safely by many major manufacturers for years. Given the low acidity of modern sulfur, you could possibly get away with it but I'd not risk it myself. I'd imagine sulfurless BP could be made to work reliably as these comps require very little priming anyway.

why don't you use a chlorate/charcoal prime, like H3, or perhaps with a small quantity of resin.

Yes, absolutely. I've even heard of H3 prime rolled on to chlorate stars acting as the burst itself in small pokka type shells. I also agree re admixtures of chlorates and metals - best avoided...

[Mnemotron]

You can use Si, though usually Chlorate stars are much more ignitable than perchlorate ones, so the Silicon is probably quite unnecessary.

I would be less comfortable using Sulfurless BP + MgAl. You've probably heard of the nitrate/Aluminium reaction. Magnalium, being 50% Aluminium counts, and because it's alloyed with Magnesium, it's more reactive.

When Nitrates react with Aluminium, ammonia is produced, as I'm sure many of us are aware from experience!

Ammonia is incompatible with chlorates in quite an extreme way, since Ammonium chlorate can be produced.

So not out of fear of the nitrate/Aluminium 'incompatibility' which everyone mixes, because it can be made stable enough to work, but out of fear of the resulting Ammonium/chlorates incompatibility I advice everyone to avoid the mixture of nitrates, chlorates and Al or MgAl.

Finally, why don't you use a chlorate/charcoal prime, like H3, or perhaps with a small quantity of resin. I am aware that many people fear the contact between the chlorate star and the BP in fireworks, but this is not as dangerous as many people believe, plus it is very safe when using the stars in shells where H3 is used as the burst, the logical option to me.

Thank you for the response.Next time i'll try with H3 mix for priming.Even if the chlorate based stars are known to be easily ignitable than perchlorate ones i have some problem with mine comps,i don't know why.For example my red star (kclo3,srco3,shellac) once primed with sulfurless BP ignite whell if i try them in a mortar,but in shells they blow blind .That's why i want to try with silicon.For priming do you suggest me to make a slurry or wet the star and rolle them in the powder?
Thank you!

[seymour]

Either method of priming will work. My personal preference is to use a slurry, and then dust it with powder to "dry it up".

If they blow blind from a shell then something is wrong. Perhaps the Strontium carbonate content, if large enough, is inhibiting the burning significantly enough to inhibit ignition, or reduce the speed at which the flame is extinguished to below the speed it's thrown from the shell at. Adding a metal to the prime seems quite unnecessary considering that there is no metal in the star composition. Potassium chlorate usually burns hotter than Potassium nitrate, so hopefully H3, or similar, will be more successful than Sulfurless BP.

Potentially they are soft, or the prime has not bonded well enough, and the burst either smashes the stars, or smashes the prime off them. Take a star, and using your fingers try to crush it. If you can, even if it hurts to do so, then I would consider this to be a likely cause of your problem.

[Mnemotron]

Either method of priming will work. My personal preference is to use a slurry, and then dust it with powder to "dry it up".

If they blow blind from a shell then something is wrong. Perhaps the Strontium carbonate content, if large enough, is inhibiting the burning significantly enough to inhibit ignition, or reduce the speed at which the flame is extinguished to below the speed it's thrown from the shell at. Adding a metal to the prime seems quite unnecessary considering that there is no metal in the star composition. Potassium chlorate usually burns hotter than Potassium nitrate, so hopefully H3, or similar, will be more successful than Sulfurless BP.

Potentially they are soft, or the prime has not bonded well enough, and the burst either smashes the stars, or smashes the prime off them. Take a star, and using your fingers try to crush it. If you can, even if it hurts to do so, then I would consider this to be a likely cause of your problem.

Ok,i'll try.Thank you for the infos!!!

[Mumbles]

Sulfur is what improves the ignitability of BP type compositions. It's possible the prime isn't lighting well, or going out at high speeds. A thicker layer would help to prevent the latter. If you watch a video you can usually tell if the prime is just burning off and not lighting the star, of if it never lights in the first place. Adding wood meal or diatomaceous earth can help to make the surface rougher, and improve ignition.