Safe to use BP burst charge with H3 primed stars?

[JTO]

Potassium chlorate is supposedly unstable with sulfur, is it OK to put stars primed with a H3 primer (75% HClO3 + 25% charcoal + some dextrin) into a device that has BP as burst charge and where they are in contact with each other?

 

[Arthur]

Well it's certainly inadvisable.

Is it possible to add a layer of sulphurless BP as a second, outer, prime? Is it possible to use a chlorate burst powder?

[JTO]

Well it's certainly inadvisable.

Is it possible to add a layer of sulphurless BP as a second, outer, prime? Is it possible to use a chlorate burst powder?

I have an idea of what I might do. I'll put a few grams a BP and a couple of H3 primed stars in a small plastic container with a lid that opens easily, so that there will be no explosion if it detonates. Then, wearing a face shield and gloves, I am going to shake it as hard as I can. Then I will store it indefinitely and repeat every once in a while, to make sure it not has somehow sensitized. If nothing happens in a year's time, I'll deem it safe :-)

[JTO]

Is H3 faster as burst charge, so that I should use less? Should it be granulated, like BP?

 

Well it's certainly inadvisable.

Is it possible to add a layer of sulphurless BP as a second, outer, prime? Is it possible to use a chlorate burst powder?

 

[SharkWhisperer]

I have an idea of what I might do. I'll put a few grams a BP and a couple of H3 primed stars in a small plastic container with a lid that opens easily, so that there will be no explosion if it detonates. Then, wearing a face shield and gloves, I am going to shake it as hard as I can. Then I will store it indefinitely and repeat every once in a while, to make sure it not has somehow sensitized. If nothing happens in a year's time, I'll deem it safe :-)

That's about the worst idea I've heard in a long time. "...shake it as hard as I can." ??? You actively going for the Darwin Award?

[sefrez]

Is H3 faster as burst charge, so that I should use less? Should it be granulated, like BP?

 

 

 

I make chlorate based fireworks (no sulfur) and use H3 burst. Yes, it burns far more aggressively so you would have to be mindful in its substitution. I see people using around 10% shell mass of BP for lift where as I use around 3-4% H3 for lift. Get the two confused using 10% H3, and you will surely be informed after lift off (think cannon) or mortar explosion. I know the prior when I did ~8% on a tiny 1" shell (call it what you want.) Intended to get ~100 ft in the air. Got ~600ft instead. I granulate the H3 with 3-5% dextrin.

[JTO]

Well, I am going to do this with a SMALL quantity, a few grams, with a container that will easily pop open and not explode if the stuff goes off, outdoors, and wearing proper gloves and a full face shield. I am certain nothing will happen to me if it should go off :-) My idea is that if I subject it to way more impact and friction than it will ever experience in actual use, then I should be able to trust that it is safe. Also, these are my first prototypes, and I plan to move to sulphurless stuff in the future.

 

That's about the worst idea I've heard in a long time. "...shake it as hard as I can." ??? You actively going for the Darwin Award?

Edited September 22, 2021 by JTO

[JTO]

 

I make chlorate based fireworks (no sulfur) and use H3 burst. Yes, it burns far more aggressively so you would have to be mindful in its substitution. I see people using around 10% shell mass of BP for lift where as I use around 3-4% H3 for lift. Get the two confused using 10% H3, and you will surely be informed after lift off (think cannon) or mortar explosion. I know the prior when I did ~8% on a tiny 1" shell (call it what you want.) Intended to get ~100 ft in the air. Got ~600ft instead. I granulate the H3 with 3-5% dextrin.

How much H3 would you use as burst charge (not lift) per, mass of stars, or per volume of the shell?

[SharkWhisperer]

Well, I am going to do this with a SMALL quantity, a few grams, with a container that will easily pop open and not explode if the stuff goes off, outdoors, and wearing proper gloves and a full face shield. I am certain nothing will happen to me if it should go off :-) My idea is that if I subject it to way more impact and friction than it will ever experience in actual use, then I should be able to trust that it is safe. Also, these are my first prototypes, and I plan to move to sulphurless stuff in the future.

 

With respect, now you're trying to rationalize an exceptionally stupid idea. Abandon that idea completely. There are established ways to test friction, heat, and shock sensitivity that don't risk your hands and eyesight. Your approach is the opposite, PPE or not. If that goes off, a loose-lidded container that pops open offers pretty much no protection, and a loose lid contradicts "shaking as hard as you can". Rethink this.

[JTO]

SharkWhisperer - I really appreciate your concern for my safety, I am attaching an image to alleviate your concerns, i.e. to show the minuteness of the quantities that I am experimenting with. I have here some granulated BP (my own), a 1 gram organic star (the small object) which is primed with H3 (75%KClO3 + 25%C + some dextrin) primer, and a piece of paper spollet fuse (my own), with a 5mm BP core, which I also dipped in H3. The matchbox is for scale. I closed the lid on this stuff, put on a glove and a full face shield, went outside, held it from the bottom with the lid facing away from me, and shook it really hard. I also dropped it on a concrete slab. As expected, nothing happened. I plan to store this indefinitely, and repeat the treatment once in a while, to make sure that any of the stuff does not somehow become sensitized over time. I am now reasonably assured that I can use the same compositions in actual pyrotechnic charges, at least until I manage to replace the BP with a sulphurless alternative. Do you agree that I am not taking any real risk here? :-)

 

With respect, now you're trying to rationalize an exceptionally stupid idea. Abandon that idea completely. There are established ways to test friction, heat, and shock sensitivity that don't risk your hands and eyesight. Your approach is the opposite, PPE or not. If that goes off, a loose-lidded container that pops open offers pretty much no protection, and a loose lid contradicts "shaking as hard as you can". Rethink this.

 

[Arthur]

The whole problem with chlorates and their incompatibilites is that they are unpredictable and unreliable. You may make things for years and be OK BUT then it only takes one explosion to cost you dearly -medical, property, legal all have risks that cost much money.

 

Most professional factories have a separate work shed and separate tools for the chlorate work.

[JTO]

Arthur - One problem is that I cannot obtain potassium percholare because of EU legislation, therefore I am pretty much stuck with potassium chlorate, and even that I have to make myself. Obviously, nothing interesting can be done without either of these substances. I have been trying to minimize risks by making very small batches at a time, say 20 grams, and by exercising great care in general. I like to do things slowly, so I can do stuff a small quantity at a time, even if I aim at a larger quantity. Do you have any suggestions as to how I could improve my processes? I always wear a face shield (not the coronavirus type, but a real one) when I handle anything potentially explosive, so, if an accident should occur despite of my precautions, I would mainly risk burns, I think.

 

The whole problem with chlorates and their incompatibilites is that they are unpredictable and unreliable. You may make things for years and be OK BUT then it only takes one explosion to cost you dearly -medical, property, legal all have risks that cost much money.

 

Most professional factories have a separate work shed and separate tools for the chlorate work.

 

[justvisiting]

There was a guy on FW, a doctor, that made a mistake with chlorate that ended his hobby and almost cost him his medical license. As it was, it cost him tens of thousands for that one mistake.

 

There was a newer pyro, Ronmoper76 that started here and then went to FW. He was a bold pyro, and thumbed his nose at safety warnings, it seemed to me. He worked with all the most dangerous stuff we use- like chlorate- and he seems to be missing now. I hope he didn't get hurt.

 

It seems to me that the best way to enjoy the benefits of potassium chlorate is to make rolled stars, and put a good layer of prime on them. Then it's only prime rubbing on prime in a shell. BP burst can be boosted with slow flash if necessary, so the only chlorate in a shell is completely encapsulated. I would feel nervous priming chlorate cut stars with BP and then loading them into a shell. I'm no expert on it though, and I know people do it, but I won't. I agree with the other guys that using chlorate where anything else could work is not a great idea. A few friction tests are no guarantee of safety. Chlorate doesn't bark, it just bites. It makes me feel queasy when I read about newer pyros using potassium chlorate. Knowing what I know now, I consider myself lucky to have all my digits after the foolish risks I've taken as a newer pyro. Be careful.

[Arthur]

In reality you need to prepare and work very carefully when only chlorates are available. Seriously consider working with sulphurless BP for burst and fusing -maybe you have to learn new rules of thumb for sulphurless spollettes. If you use a bag to separate your stars from your burst you may be lucky. Realistically once you use chlorate colour comps you should plan to be without sulphur in any of your components.

[JTO]

Justvisiting - The stars which I have made so far are chlorate-based, both metallic (Al) and organic. After experimenting with various compositions I now have, I think, a reasonably good recipe for white, red and blue stars. I have made them by pressing them with a syringe with the end cut off (is this what you call pressed stars?) a small quantity at a time, spurting them on a glass plate, then primed them with H3 after they have hardened. So, both the stars and the primer are all chlorate based, no sulphur present. But it worries me a bit using BP as the burst charge, because BP obviously contains sulphur. I am going to assemble and test my first airburst device soon, which is a 60mm shell. Do you think I am on the right track or should I change something? I would like to avoid risks as much as possible.

 

There was a guy on FW, a doctor, that made a mistake with chlorate that ended his hobby and almost cost him his medical license. As it was, it cost him tens of thousands for that one mistake.

 

There was a newer pyro, Ronmoper76 that started here and then went to FW. He was a bold pyro, and thumbed his nose at safety warnings, it seemed to me. He worked with all the most dangerous stuff we use- like chlorate- and he seems to be missing now. I hope he didn't get hurt.

 

It seems to me that the best way to enjoy the benefits of potassium chlorate is to make rolled stars, and put a good layer of prime on them. Then it's only prime rubbing on prime in a shell. BP burst can be boosted with slow flash if necessary, so the only chlorate in a shell is completely encapsulated. I would feel nervous priming chlorate cut stars with BP and then loading them into a shell. I'm no expert on it though, and I know people do it, but I won't. I agree with the other guys that using chlorate where anything else could work is not a great idea. A few friction tests are no guarantee of safety. Chlorate doesn't bark, it just bites. It makes me feel queasy when I read about newer pyros using potassium chlorate. Knowing what I know now, I consider myself lucky to have all my digits after the foolish risks I've taken as a newer pyro. Be careful.

 

[JTO]

What composition would you recommend as burst charge and in spolettes? At least in spolettes one surely cannot use H3 because they would burn through in about three nanoseconds or possibly even explode :-)

 

In reality you need to prepare and work very carefully when only chlorates are available. Seriously consider working with sulphurless BP for burst and fusing -maybe you have to learn new rules of thumb for sulphurless spollettes. If you use a bag to separate your stars from your burst you may be lucky. Realistically once you use chlorate colour comps you should plan to be without sulphur in any of your components.

 

[justvisiting]

Pressed stars have edges and the prime doesn't cover them completely and evenly like it does with rolled stars. I would be nervous adding black powder burst and closing a shell with those kind of stars too. I'll let others that know more than me advise you on that, but you might look into rolling your stars instead of pressing or cutting in the future.

 

A retired fireworks manufacturer named Bill Ofca wrote a series of pamphlets called 'Technique in Fire'. One volume was specifically devoted to working with chlorates. I don't have it any more, but it was a good read.

[Mumbles]

With regard to your testing method, I wouldn't assume that a loose lid will prevent anything from exploding. Your amounts are small and the walls are thin, which helps. Compositions burn faster under containment. It's very possible to over-pressurize the container and have it explode before the lid is dislodged.

 

Most people I'm familiar with would probably suggest to prime your stars with BP instead of H3. It probably seems counterintuitive at first. The rationale is that it's better to have the BP and chlorate in firm, bonded contact with each other. The biggest issue tends to be friction. Having it bound reduces this risk, and reduces the risks during loading, settling, and shooting. BP burst granules are more likely to cause an issue rubbing up against chlorate primed stars, than BP prime is likely to cause issues by being in contact with chlorate stars.

 

There have been a large number of successful shells fired the way I described with the BP priming if that gives you some ease of mind. Nothing is without risk of course. If your shell fails to passfire from the spolette to the burst, these shells have been known to be more likely to explode if they re-impact the ground. Just a heads up.

[sefrez]

How much H3 would you use as burst charge (not lift) per, mass of stars, or per volume of the shell?

 

I can't say really. Depends on too many things. Though I kind of lean on the assumption that "its probably going to break harder than I think" and go from there. Not great advice, I know. Really for me it has been trial and error, and making changes to correct those errors.

 

 

There was a guy on FW, a doctor, that made a mistake with chlorate that ended his hobby and almost cost him his medical license. As it was, it cost him tens of thousands for that one mistake.

 

There was a newer pyro, Ronmoper76 that started here and then went to FW. He was a bold pyro, and thumbed his nose at safety warnings, it seemed to me. He worked with all the most dangerous stuff we use- like chlorate- and he seems to be missing now. I hope he didn't get hurt.

 

It seems to me that the best way to enjoy the benefits of potassium chlorate is to make rolled stars, and put a good layer of prime on them. Then it's only prime rubbing on prime in a shell. BP burst can be boosted with slow flash if necessary, so the only chlorate in a shell is completely encapsulated. I would feel nervous priming chlorate cut stars with BP and then loading them into a shell. I'm no expert on it though, and I know people do it, but I won't. I agree with the other guys that using chlorate where anything else could work is not a great idea. A few friction tests are no guarantee of safety. Chlorate doesn't bark, it just bites. It makes me feel queasy when I read about newer pyros using potassium chlorate. Knowing what I know now, I consider myself lucky to have all my digits after the foolish risks I've taken as a newer pyro. Be careful.

 

Do you know what that mistake was?

 

Justvisiting - The stars which I have made so far are chlorate-based, both metallic (Al) and organic. After experimenting with various compositions I now have, I think, a reasonably good recipe for white, red and blue stars. I have made them by pressing them with a syringe with the end cut off (is this what you call pressed stars?) a small quantity at a time, spurting them on a glass plate, then primed them with H3 after they have hardened. So, both the stars and the primer are all chlorate based, no sulphur present. But it worries me a bit using BP as the burst charge, because BP obviously contains sulphur. I am going to assemble and test my first airburst device soon, which is a 60mm shell. Do you think I am on the right track or should I change something? I would like to avoid risks as much as possible.

 

 

 

Mind sharing your white formula? I haven't made any chlorate based stars containing metallic fuel. I don't think chlorate + metal is so much unpredictable (like chlorate + sulfur) as it is friction sensitive. All things pyrotechnic have the ability to go up, that is their purpose. We just want to have say so when they do. I'll deal with a predictably sensitive composition before I would an unpredictably "moderately" stable one. I may do some chlorate / metal (no magnesium... thats really unnecessary) composition tests in the future, but for now I'm leaving the metal with perchlorate.

 

What composition would you recommend as burst charge and in spolettes? At least in spolettes one surely cannot use H3 because they would burn through in about three nanoseconds or possibly even explode :-)

 

 

 

 

In using a chlorate system, I did some chlorate spolette composition tests a while back. This included an H3 test. As one would guess, It burns far too fast.

 

 

Dextrin is a poor fuel in comparison to charcoal and so I came up with some mixtures of varying burn rate by varying the ratio of charcoal to dextrin maintaining the overall oxidizer to fuel ratio as in H3. They all seem to burn reliably although more dextrin = slower = less energetic. You don't typically see dextrin as a fuel but rather as a binder. But I don't mind breaking that standard. You could possibly even substitute corn starch with little change if not using the solubility properties of dextrin. I've not bothered with that however.

 

KClO3, 66, Charcoal 13, Dextrin 21: 9.2mm/s

KClO3 65, Charcoal 10, Dextrin 25: ~5.8mm/s

KClO3 64, Charcoal 9, Dextrin 27: ~5mm/s

 

I have used the last one. Here is a test of that (I think, video was old with no title):

 

 

These are just 2.2mm. Generally, the lower the cross-section the less reliable. So if it burns reliably at 2.2mm, it should definitely work at more typical diameters. Speed will be dependent, so testing is essential. It lights pretty easily, although not as easy as H3. Iv'e had no issues getting it to light with the black match I mentioned before. But you could press a "prime" layer of H3 at the ignition side as well. Still, I think you should really use match of some type that has much exposure to lift giving a solid path to spolette comp.

 

 

I'm currently using a perchlorate composition now with metallic fueled granules for sparkling effects. A tiny 1" canister using such small spolette.

 

Edited September 23, 2021 by sefrez

[justvisiting]

Sefrez, the chlorate mistake was one that's so unlikely to be repeated that I didn't bother to mention what he did, but I'll relate it from memory:

 

He wanted to make some lampblack streamer stars from a formula in an old book by Weingart. Chlorate was the oxidizer. The instructions were to press the damp starmix in bundles made of cloth to firm it up, and then let the 'cake' dry. After that, the cakes were to be broken up into pieces prior to use. The prevailing wisdom in pyro at the time was to prime everything, whether needed or not. The guy primed the cake with a black powder-type prime. Then he went to cut the primed cake with a sharp knife, I believe on a porcelain slab. The whole thing went off and started a fire.

[SharkWhisperer]

"Shaking" a pyro comp "as hard as you can" to test stability/safety is just plain dumb. No way to state it otherwise.

 

You seem like an inquisitive experimenter, and that's great.

 

You'll probably get away with it, but more concerning is what else you won't get away with in the future.

 

Not a fan.

[JTO]

Thanks! Unfortunately the publication seems to be pretty hard to find, too esoteric I guess.

Pressed stars have edges and the prime doesn't cover them completely and evenly like it does with rolled stars. I would be nervous adding black powder burst and closing a shell with those kind of stars too. I'll let others that know more than me advise you on that, but you might look into rolling your stars instead of pressing or cutting in the future.

 

A retired fireworks manufacturer named Bill Ofca wrote a series of pamphlets called 'Technique in Fire'. One volume was specifically devoted to working with chlorates. I don't have it any more, but it was a good read.

Edited September 23, 2021 by JTO

[JTO]

My true and tried white composition is very simple :-)

50% KClO3

40% aluminum (very fine, airfloat, don't know the particle size because I milled it myself, but it is so fine that one batch turned out pyrophoric)
10% shellac (already dissolved in ethanol) (shellac is cheap at Aliexpress!)
For me, the shellac-ethanol solution alone is adequate to moisten the mixture, no water or ethanol needs to be added. I am using a ready-made shellac-ethanol solution with 50g shellac and 200ml ethanol. I used a syringe to estimate the quantity of shellac, assuming 5ml of solution = 1g of shellac.

These stars are pretty fast and very bright.

I pumped them on a glass plate using a syringe with the end cut off to form 1g stars. Afterwards dipped then in H3 primer with some dextrin as binder.

I also tried a version with dextrin as binder, it was inferior (burned at least as fast but was not as bright).

Mind sharing your white formula? I haven't made any chlorate based stars containing metallic fuel. I don't think chlorate + metal is so much unpredictable (like chlorate + sulfur) as it is friction sensitive. All things pyrotechnic have the ability to go up, that is their purpose. We just want to have say so when they do. I'll deal with a predictably sensitive composition before I would an unpredictably "moderately" stable one. I may do some chlorate / metal (no magnesium... thats really unnecessary) composition tests in the future, but for now I'm leaving the metal with perchlorate.

 

[JTO]

Isn't BP worse because in my experiments it seems to burn *far* less aggressively that H3, which would suggest that the chance of a blowout or failure to ignite would be greater with a BP primer than with a H3 primer?

 

Most people I'm familiar with would probably suggest to prime your stars with BP instead of H3.

 

[JTO]

Thanks, I'll try to be extra careful with everything I do, always wear protection, and only work with small batches in the range of a few tens of grams at a time. My biggest problem probably is that I am stuck with potassium chlorate because I live in the EU, I would like to use percholarate but it cannot be purchased here (neither can chlorate but I make it myself). Thanks once more for your valuable feedback.

 

You'll probably get away with it, but more concerning is what else you won't get away with in the future.