8 replies to this topic

[pyromaniac303]

I've recently been looking for a black smoke comp for daylight pyro, and noticed several comps containing anthracene and napthalene, both extracted from coal tar.

After looking round for napthalene mothballs for a while, it seems theyre getting hard to find, and after a bit of research discovered the alternative mothball ingredient (paradichlorobenzene) is also extracted from coal tar so I decided to give it a try.

After testing several comps it seems that the stuff just wont burn at all, and in fact would make an excellent fire suppressant as it bubbles up around the flame and smothers it. Can anyone explain why the huge difference in properties between the coal tar derivatives?

Also any suggestions for dark smoke comps without dyes would be greatly appreciated.

Edited by pyromaniac303, 02 June 2008 - 07:43 PM.

[BrightStar]

Alas, I don't know anything about the combustion of paradichlorobenzene.

You can however reportedly make a two component black smoke with a mix of Polystyrene and Potassium Chlorate. I don't know the proportions but it would be an interesting experiment to try...

Edited by BrightStar, 02 June 2008 - 08:29 PM.

[Arthur Brown]

Organic Chlorine IS a fire suppressant! So it will inhibit flame! It may be needed as a colour promoter BUT too much and it's a flame suppressant.

[icarus]

naphthalene was often used finely powdered fired and ignited by a bp charge in a tube to simulate fiery explosions in old films

[pyromaniac303]

Thanks for all the replies, theres been a lot of good info. The paradichlorobenzene seemed to be turning molten and bubbling up over the flame, extinguishing it and then solidifying again with no sign of discolouration. I have read from several sources that it is flammable, and on the MSDS it says avoid contact with oxidisers, so I still can't really explain its behaviour fully. I don't think the extinguishing effect is purely down to chlorine production, as it had its own oxidiser (50% perchlorate).

The comps tested were variations of perchlorate, paradichlorobenzene, sulfur and magnallium, starting with:

Potassium perchlorate 5g
Paradichlorobenzene 3g (99.6% pure according to the pack, the 0.4% I assume is a binder)
Sulfur 2g
200 mesh magnalium +2g

I do realise the perchlorate-sulfur incompatibility here, and was trying to just get a working product from a similar formula I found on the jackery pyro database, in a small quantity, then once I had obtained a working black smoke I was going to modify it to make it safer.

After thoroughly testing and proving that the comp was practically useless, I added the magnalium to try and increase the burn rate and temperature so it would self-sustain. Now once lit it 'strobes' slightly before going out. I think I am about ready to give up with it.


That polystyrene and chlorate comp sounds interesting. Do you know if the polystyrene is the expanded form or the normal form? Or if it should be dissolved in a solvent and bound with the polystyrene solution.

[GalFisk]

What's the perch/S incompatibility? I haven't read about that (chlorate sure, and someting about AP+S being sensitive iirc)
I have some naphthalene, could you post or point me to some of those smoke formulas?
I could send you some for the price of the chemical+shipping (from Sweden), if I can find a good way to seal it in hermetically, because this stuff reeks. The local paint supply store carries it in its line of base chemicals (along with sulfur, shellac and other goodies).
I have no personal experience with any polystyrene comp, but PS in acetone seems like the way to go. When the acetone evaporates the plastic will be solid. Expanded PS dissolves instantly, I think normal PS must soak overnight if not longer. Oh, and some packing peanuts really stink when dissolved, so don't use those.

[pyromaniac303]

Perchlorates are only a small amount less sensitive than chlorates with regards to sulfur sensitivities. Heres what Ron Lancaster has to say on the subject:
"Some firework makers add sulfur to perchlorate mixtures, and while it must be admitted that such mixtures are less sensitive than chlorate mixtures, they are best avoided. Tests seem to indicate that mixtures of perchlorate and sulfur are only marginally less sensitive to impact and friction."
From Fireworks, Principles and Practice 4th edition, p144.


I think the smell given off is pentane, as that is used in polystyrene foam manufacture. Thanks for the offer, I have found several sources for it online within the UK but thought I would try out the paradichlorobenzene as it was an interesting experiment.

I got a similar formula from www.jackerypyro.com, which now seems to be offline. When its back on again its worth a visit, there is an excellent formula database, fully searchable, and users can contribute their own formulae. This does mean that you should double check what your making for incompatibilities though, as there are a few dangerous looking ones.

[GalFisk]

Thanks, interesting point about perch/S, it doesn't often seem to be mentioned along with other compatibility issues. The smell from the packing peanuts reminded somewhat of leek or garlic, white styrofoam from a computer box didn't smell at all (at least not detectable over the smell of acetone). Yes I've melted stuff with acetone just for fun.
I found a few black (and other color) formulas here, I'm getting Sb2S3 from Keten soon (hope it's soon anyway), worth a try.
http://www.sciencefo...r...5543&page=2

Edited by GalFisk, 03 June 2008 - 09:37 PM.

[Arthur Brown]

While they were extracted from coal tar look! they are still on the market. One problem is that the Naphthalene is very toxic to all forms of life and shouldnt get on the ground or waterways as it kills everything.

www.camlab.co.uk/item.asp?itemid=21793&categoryid=718&browsecategoryid=20

Strangely the 500g is cheaper than the 1Kg pack pro rata.

Google 120-12-7

for info on Anthracene c&p that exactly, it's all you need!