Flour based stars

[TomasBrod]

Organic pyrotechnic stars, as name suggests, use some kind of organic fuel. Common organic fuels are shellac, colophony resin, red gum, dextrin, parlon and pvc. The later two serving dual role as a chlorine donor. Now these chemicals, while unrestricted, are not particular common. Because of that, I decided to look at commonly available organic materials.

First, let's look at he unsuitable ones. Sughar is very hygroscopic when mixed with sodium chlorate. Citric acid is also very hygroscopic. Candle-wax makes secondary high explosive.
Wheat Flour appears to be good candidate: it is not as strong in reducing potential, but it is not hygroscopic. It comes conveniently powdered in multiple degrees of fineness and is cheap. When mixed with sodium chlorate, it burns tamely with well-formed flame envelope. The flour, when activated with water, acts as a binder too. The chemical composition of flour can be approximated to starch with the chemical formula of C6H10O5. When calculating amount of oxidizer, combustion to CO and H2O should be considered, not CO2.
When mixed with just chlorate, it does not burn very fast and is hard to ignite. Charcoal powder was found to be good additive to improve burn speed and flame sensitivity. Added charcoal should be balanced with extra oxidizer.
Some years ago I developed a formula of 4:1:8 (flour:carbon:chlorate), but recently I changed the ratio because it was not sensitive enough.

 

Wheat Flour ... 12
Charcoal ... 4
Sodium Chlorate ... 28

 

Wet with small amount of water. This composition can be pressed into comets, or moisturized more and cut. Obviously, it burns yellow due to all that sodium.

Next step in development is to replace most of the Sodium chlorate with more stable potassium chlorate.