7 replies to this topic

[Neway]

Hello to everybody! Until now I have made only charcoal stars, but now I'm ordering some chemicals from keten, but they doesn't have red gum. Could I use shellac instead of red gum?

Thanks a lot!

[chris17]

Hello to everybody! Until now I have made only charcoal stars, but now I'm ordering some chemicals from keten, but they doesn't have red gum. Could I use shellac instead of red gum?

Thanks a lot!

I have never worked with shellac myself, so I am unable to answer your question. I can, however, suggest substituting red gum with pine rosin 1:1 in certain formulas. Pine rosin is a very clean burning fuel, which I use commonly. It should available at hardware stores in a chunky form. You need to either grind it with a bill mill or buy it in a powder form. The chunks break up easily and the resulting powder is a very fine, yellowish heavy powder.

Hope this helps.

Edited by chris17, 22 February 2008 - 01:08 PM.

[pyrotrev]

Shellac gives a good clear flame but I've found it a lot less ignitable and smooth burning than red gum when using KClO4 as the oxidiser, so maybe it's not an exact replacement when it's the main fuel. Inoxia and Cooperman do stock red gum (accroides resin) though.

Edited by pyrotrev, 25 February 2008 - 08:07 PM.

[Neway]

Ok, thanks, I think I will buy red gum from another seller!

[pyromaniac303]

I ordered red gum from keten, maybe he's ran out temporarily. Well anyway shellac is not as easy to work with, to start off with youll end up with it in large flakes, which have to be ground finely or dissolved in boiling alcohol. It is NOT very soluble in cold alcohol, not tried with acetone yet though.

Reproducing some of Weingarts lance comps containing chlorate and shellac was quite nice, though I still prefer red gum for stars as it gives slightly better colours and burns less smokey.

[KarlosH]

Shellac is not good binder, not good fuel. Shellac work only in blue compositions with CuO and potassium perchlorate.
If you want use shellac, I advise only 5 - 6% for metalic fuelled stars, only pumped or cut, and igniting composition must be perfect. Shellac decrease ignition, and inhibit burning! I use synthetic resin Ribetak instead of red gum, Ribetak is perfect binder, like dextrin, perfect fuel.
Bye.

[Bonny]

Shellac is not good binder, not good fuel. Shellac work only in blue compositions with CuO and potassium perchlorate.
If you want use shellac, I advise only 5 - 6% for metalic fuelled stars, only pumped or cut, and igniting composition must be perfect. Shellac decrease ignition, and inhibit burning! I use synthetic resin Ribetak instead of red gum, Ribetak is perfect binder, like dextrin, perfect fuel.
Bye.

I prefer red gum, but I have used shellac successfully in chlorate reds and greens as well as blue. The stars took AGES to dry but worked fine once they were fired, although they were a little slow burning, just have to make them smaller. They were not brittle either, so I think they would easily withstand very hard breaks.
To grind it, freeze it first to make it more brittle and then run it in the coffeee mill.

[nakaora]

I order Shellac to Kremer Pigmente GmbH, very cheap and they don't apply non justified high post costs.