Sciencemadness Discussion Board

SGRS - Soluble Gelatinous Rice Starch

Simoski - 16-4-2020 at 16:03

Hello it's the end of the world and I have been trying desperately to make a simple reliable fuse during lockdown here in South Africa that I can trust with my life. ( So here comes a story about SGRS )

Without building an underwater fuse which I am sure I will get to in this life, rather when I say reliable fuse I am looking for 3 things, constant burn rate, passfire and non-hygroscopic.

I have tried lots of different ideas to waterproof my cotton string impregnated sugar/Chlorate fuse. And the best thing I have found is hot gelatinised pasta starch.

It's during my testing 101 different waterproofings that I have come to understand SGRS... Gelatinous rice starch.

The amateur Pyro forums talk about SGRS and make reference to Shimizu's work and multiple methods to create said SGRS, none however explain it succinctly or with good understanding.
It is my pyrotechnic quest for water resistance combined with my understanding of gelation from soap making that have lead to the understanding that I here depart.

Simple put... Gelation of starch requires 2 things: water and heat. If you allow a solution of rice starch, or pasta starch for that matter to cool, you will notice a starch precipitation forms as it cool. Basically it drops out of the gel phase to the solid phase.

The pyrotechnician must first heat the starch in water to get it to the gel phase before use. Rice/pasta starch in room temperature water does not work well.

[Edited on 17-4-2020 by Simoski]

ShotBored - 17-4-2020 at 12:36

I've messed with SGRS a bit, but I always figured it would still fall apart when reintroduced to water, slowly in cold water or at the very least that it would swell. I'd give Klucel a look for coating your fuse, as it's used in leather tanning specifically to keep water out and is soluble in ethanol and IPA. Should be readily available and fairly cheap. If you're set on water-binding, polyvinyl alcohol or polyvinylpyrrolidone are worth a look. I've found that polyvinylpyrrolidone seems to affect burn characteristics a lot less than any other binder I've messed with, but it's a bit spendy.

Simoski - 17-4-2020 at 23:18

Thanks ShotBored