Bju90 Posted March 10 Posted March 10 I want to replace red gum with shellac in the following formulas. Red gum is not readily available here in small quantities so it's super expensive @ $70/100g compared to shellac at less than $14/100g. Unless someone also in Australia has excess red gum and want to sell me some, pm me :). Component Red Green Yellow Peach/Lavender Strontium nitrate 0.53 0.13 Barium nitrate 0.53 0.40 Potassium nitrate 0.53 Magnalium 0.19 0.19 0.19 0.19 Parlon 0.17 0.17 0.17 0.17 Red gum 0.11 0.11 0.11 0.11 From reading various posts it should work but there are mixed experiences with shellac vs red gum in various comps. Everything I could find was to do with perchlorate vs chlorate comps. I'll start experementing to see but it would be helpful if anyone else has had any experience with these particular comps as a starting point. According to ChatGpt shellac has a higher oxygen demand by aabout 22% so will have to account for that. Resin Oxygen Demand (g O₂/g) Relative Difference Red Gum 1.78 g O₂/g Lower Shellac 2.17 g O₂/g Higher My other concern is drying. From previous threads users reported shellac being more difficult to dry if there was too much solvent used. I will be using acetone, much cheaper than denatured alcohol here.
Carbon796 Posted March 11 Posted March 11 Phenolic resin would be a better substitute. If you have access to it. If your not stuck on solvent binding. You can just add a water based binder. That will also eliminate any solvent entrapment issues.
Bju90 Posted March 13 Author Posted March 13 I looked for that but cant find anything unless I purchase commercial quantities. Can I clarify if you are referring to the binder as the Red Gum or the Parlon? I thought in this application the Parlon is acting as the Binder/Chlorine donor and the Red Gum is primarily there as a fuel, in which case the Parlon won't activate with the water? I have a decent amount of Parlon so i'd prefer to use that. This might be a dumb question but can a water soluble binder/fuel be used in place of the red gum and press the stars rather than making rubber cut stars?
Bju90 Posted March 13 Author Posted March 13 (edited) Something like this with water or water/alcohol to make a pumped star. Component Red Strontium nitrate 0.53 Magnalium (Mg/Al) 0.19 Parlon 0.17 Sulfur 0.07 Dextrin 0.04 Edited March 13 by Bju90 Error.
Carbon796 Posted March 13 Posted March 13 If you used alcohol, it would dissolve the RG or shellac. But not the parlon. If you used acetone it would dissolve the RG or shellac and soften the parlon. Subbing for sulfur and adding dex. Activating with water should work well. 1
Bju90 Posted March 13 Author Posted March 13 Tried a small amount with the Sulfur and dextrin as above. Hand pressed some of the comp dry in to an 8mm paper tube to test it. Don’t have anything to compare it to but it’s lit up easy, burnt red and bright. I will make a few pumped stars over the weekend and see how they go. IMG_5617.mov
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