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Novolak rosin in star comps


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#1 Powderman

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Posted 14 October 2021 - 01:50 AM

It is very difficult to get red gum or parlon here, but I was lucky to find at least some PVC and novolak (low molecular weight phenolic rosin soluble in acetone). But now I have problem finding star formulas which can utilize these. Are there any clues how to substitute with these in existing formulas, or maybe there are ready made formulas? Or at least where to begin when composing new formula? I do understand it is consisting of oxidiser/fuel/flame colorant/chlorine donor/binder but are there any tips on which combination try first?

I would like to make colored stars if it is unclear from my questions...


Edited by Powderman, 14 October 2021 - 01:54 AM.


#2 Crazy Swede

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Posted 14 October 2021 - 08:21 AM

Novolac resin is a very good fuel and can replace red gum in a 0.82:1 ratio (i.e., only use 0.82 % of the amount of red gum in the original formula).

 

PVC has a lot higher fuel value compared to chlorinated rubber but contains less chlorine, so it is a bit more tricky to recommend a general way of substitution there. It depends of the type of formula. Try to search here, I'm sure it has been discussed.


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#3 robbo

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Posted 14 October 2021 - 03:54 PM

I think our Swede meant 0.82 x of the red gum, i.e., 82% of the RG weight.  It works fine.

 

Shellac is an old-fashioned, expensive (but great) fuel/binder for some stars that you might pick up at art supply stores.  Make sure you get a powder, though.

 

You might be able to get some chlorinated rubber from a paint manufacturer.  I think it's a film-former.  We used to get our "Superchlon" (a Japanese chlorinated alloprene) from a local paint making factory. 

 

If you're interested in hexamine, you might find it available in the form of smokeless campstove "Esbit" tablets (I think that's the name). 

 

Post here about what else you need - many things can be gotten from  alternative non-pyro sources.



#4 Powderman

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Posted 16 October 2021 - 11:42 AM

Thank you both very much!

So it seems at least red gum can be substituted, I will try to find some way to get chlorinated rubber, and till then I can try something with PVC. 

Shellac can be bought here but only flakes, and I think I know why powdered is better :-)

Hexamine tablets slowly disappear from stores so I bought this year few boxes just in case :-)






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