6 replies to this topic

[GreenGenie]

1***) I have been planning on trying out the Robert Veline colour compositions. Ive been looking forward to it. I have been reading the MSDS sheets on both Potassium Perchlorate and Ammonium Perchlorate in preparation for this and I was struck that both of these chemicals have incompatibilities with metals generally. Potassium Perchlorate has incompatibilities with Aluminium and Magnesium specifically highlighted. Velines compositions contain both Potassium Perchlorate and a quantity of Magnalium.

Now I understand that Robert Velines Compositions are well established standards but given Perchlorates incompatibility with metals and Magnesium and Aluminium in particular how is it that the addition of Magnalium doesn't lead to a dangerous instability when combined with the Potassium Perchlorate? I have noticed this practice is not solely confined to the Veline compositions.

2***) Can Ammonium Perchlorate be substituted for Potassium Perchlorate in Velines compostions and for that matter all compositions?

3***) I notice that BP primes are used with compositions containing Perchlorates. Both Sulphur and Charcoal are listed as incompatible with Potassium Perchlorate. Again using a BP prime with a Perchlorate is bringing incompatible chemicals in contact with each other. Does this not lead to a dangerous instability?

Sulphur and Charcoal (Or Aluminium and Magnesium come to that) are not listed as incompatible with Ammonium Perchlorate on the MSDS sheet that I read; but I suspect that if it is incompatible with Potassium Perchlorate it is probably incompatible with Ammonium Perchlorate too. Is my assumption correct?

4***) I have recently been using aluminium coke cans to weigh out compositions. They combine a large capacity with a small base and they sit neatly on my small scales. I thought they would be suitable to use for compositions as they are non ferrous. Is it dangerous to use an Aluminium container to weigh out perchlorate? I weigh each of the chemicals into the same can (unmixed) prior to tipping it out on a sheet of paper and then mixing by the diapering method.

5***) I have read that metal oxides are incompatible with Chlorate is that also true with Perchlorates? I have made a Shimizu Blue with Potassium Perchlorate and Copper Oxide and Conklin has one too.

[portfire]

First, I'm sure you'll get a more indepth reply than mine and second, your a bit like me when I first started out, SAFETY, which is a good thing and should always be at the top of your list...

The Veline system is a good place to start with colours, it's tried, tested and proved!!! Don't worry about the incompatibilities, just take the standard safety precautions

[fruitfulsteve]

If everything in pyro was completely compatible/stable/safe they would not light. I think what we do is based on a bit of incapability to produce energetic mixtures. After all most containers of oxidisers will warn you not to mix them with combustible materials most metal powders are combustible as are a lot of other things we mix with oxidisers. MSDS are their to prevent people accidently making stuff we may be making deliberatly. Having said that i wouldn't want to replace kclo4 with nh4clo4 in a formula with any sort of clo3 in it.

[seymour]

Fuels sensitise oxidisers.

However that is the point. We want the mixture to be sensitive enough to ignite when we want it. With Perchlorates we are lucky, because nothing makes it too sensitive, like Fruitfulsteves mention of Ammonium salts and chlorates. These should never be mixed!

Some fuels sensitise perchlorates more than others. A resin fuel like Red Gum or Shelac will sensitise it less than a metal fuel. Sulfur will sensitise perchlorates quite a lot, but this is usually made ok because the sulfur is quite a small percent, diluted by other chemicals.

Different materials sensitise in different ways. Fr example fine charcoal makes things very sensitive to ignition through sparks or flames, but not from impact or frction. Magnalium however, because it is abrasive, makes things quite sensitive to shock and friction, but not nearly as much to sparks as charcoal.

So, getting back to my Main point. Fuels sensitise oxidisers. If you ask a chemist what you should not add to Potassium perchlorate, they will tell you what not to add, because it will turn it in to a firework. They are trying to avoid making fireworks. We are not.

It is a good thing you are being careful!

Sulphur and Charcoal (Or Aluminium and Magnesium come to that) are not listed as incompatible with Ammonium Perchlorate on the MSDS sheet that I read; but I suspect that if it is incompatible with Potassium Perchlorate it is probably incompatible with Ammonium Perchlorate too. Is my assumption correct?

Here is a great example of how useless MSDS sheets can be. Ignore the fact that KP is 'incompatable' with Charcoal. It is quite sensitive to shock with Sulfur, but not enough to make it unusable. But Magnesium... this stuff is about as incompatable with Ammonium perchlorate as you can get without being lethal.. It reacts like mad and will cause you much suffering unless you prepare it PERFECTLY. This involves coating it with a solution of Potassium dichromate, drying it, and then binding the composition with Nitrocellulose, using a dehydrated solvent, and dehydrated chemicals.

5***) I have read that metal oxides are incompatible with Chlorate is that also true with Perchlorates? I have made a Shimizu Blue with Potassium Perchlorate and Copper Oxide and Conklin has one too.

As with fuels, Copper oxide helps things burn, and thus chemists want to avoid it. We do not. It its a catalyst for both chlorates and perchlorates, which means that the composition will light easier and burn faster with it.

2***) Can Ammonium Perchlorate be substituted for Potassium Perchlorate in Velines compostions and for that matter all compositions?

As mentioned Ammonium salts just can not go together with chlorates. Amonium chlorate is formed when they meet, and this is one of those really really dodgy explosives. Other than that, Ammonium perchlorate reacts with many chemicals in ways that are not dangerous, but ruin the composition. These include Potassium nitrate and magnalium.

Finally, they have different oxygen contents, so they will not behave the same if used interchangeably.

I think the short answer is no.

While I agree with what has been said about the Velines being straightforward, and simple while working, and thus being a good first step, look out for better formulas. When people keep going on about a formula, and it has similar chemicals, it's probably better. Veline colours are not all great on the colour side of things, not that they are bad either.


I hope my ramble helps and is readable

[pyrotrev]

Check places like the PFP for specific AP based compositons - the colours tend to be bright and so much more saturated that you'll never look back. There's some good ones in Shimizu's book too.

[Creepin_pyro]

Great to see someone really paying attention to the safety side of things - this is a very good start. You will soon learn to read between the lines of MSDS sheets!

Now I understand that Robert Velines Compositions are well established standards

Not quite 'standards'. They are a compatible system for colour mixing - none of the actual individual colours themselves are particularly good. Their strength (other than using similar, relatively easy to find chemicals) is that they work well as a set and complement each other - when seen together they are well balanced in terms of brilliance, saturation etc.

If you're looking for the best colours using a colour mixing system I would recommend looking into Baechle's formulea.

If you do venture into the world of Ammonium Perchlorate colours you really need to familiarise yourself with how to use the appropriate non-aqueous binders, and any potential incompatibilities. You're certainly heading in the right direction in this respect.

[GreenGenie]

Thanks guys for your excellent explanations and for helping me up another rung on the ladder of understanding.