deepakpyro Posted May 30 Posted May 30 I am having about 2 pounds of red gum and trying to make stars with red gum as binder. I made a small batch of independence red pumped stars with red gum by activating the red gum with Denatured alcohol. I do see, after wetting the mix with alcohol, the mix is look like wet loose powder mix but not something like dough consistency. When i hand pump it, the star came as good shape not crumbled. But i see the binder was actually doing it job when it is atleast 50% dry and it is fragile before that. On complete dry for 3 days in the shade, few starts are hard but few got crumbled when handled (maybe top layer of mix is dried when pumping). Is red gum binded stars are strong enough for hard break ? Is there baseline qty that needed to activate the red gum ?
Crazy Swede Posted May 30 Posted May 30 The original Independence Red formula contains dextrin and is supposed to be moistened with water. Due to its content of strontium nitrate they can be difficult to dry though if you live in a humid climate. Red gum is not a good binder and you should not rely on its binding power unless you press stars/comets with heavy pressure. Regarding the consistency of moistened compositions they should not be like a dough if they are to be pressed! Try acetone, or a mix of 50/50 ethanol/acetone, to also activate the chlorinated rubber. Leave the composition moistened in a solvent tight container for 20 minutes or so to really let the red gum and chlorinated rubber to be partly dissolved before pressing.
SharkWhisperer Posted May 30 Posted May 30 3 hours ago, Crazy Swede said: Red gum is not a good binder and you should not rely on its binding power unless you press stars/comets with heavy pressure. Try acetone, or a mix of 50/50 ethanol/acetone, to also activate the chlorinated rubber. Leave the composition moistened in a solvent tight container for 20 minutes or so to really let the red gum and chlorinated rubber to be partly dissolved before pressing. I make a lot of cut rubber stars & like the Swede says, acetone (or EtOH/acetone mixture) may work better than just alcohol for binding--Parlon/chlorinated rubber won't dissolve in alcohol and RG often requires some exposure time to alcohol to completely dissolve. Parlon dissolves in acetone very readily & I don't find the parlon/acetone needs more exposure time than it takes to mix the solvent into the comp, but if won't hurt anything to try. It may help for pumped stars that use less solvent, though. My rubber reds are pretty close to Independence Red (https://www.fireworkscookbook.com/firework-recipe/independence-red/). The common formula uses 50.5% (call it 51%) strontium nitrate; Gorski's/Skyrobber's red rubber formula is 53% (https://www.skylighter.com/blogs/how-to-make-fireworks/screen-sliced-red-rubber-stars). I round up to 55% (with 20% MgAl -200, 15% parlon, 10% RG; nice easy numbers with good results). Like others, I avoid using water/dextrin for comps that use strontium nitrate whenever possible. Parlon-bound cut red rubber stars are durable & store well even without desiccation. I also use RG instead of dextrin in nearly all of my priming comps, typically using 91% IPA as solvent. I like the faster drying than dex/water and the prime adheres just fine at 5% RG. Per Swede, try an alcohol/acetone solvent combination so you can take advantage of the binding potential of both your RG and your parlon/rubber. Increasing the alcohol fraction slows evaporation and increases working time. Agree 50/50 is a good starting point.
Zumber Posted May 31 Posted May 31 Alcohol evoprates faster and red gum needs some time to dissolve and activate. I prefer dextrin water and use red gum as a fuel than binder.
Mumbles Posted May 31 Posted May 31 I haven't cut a lot of stars with red gum as the binder, but I have used it often as the binder with isopropyl alcohol for primes. It adheres pretty well for that and dries fairly hard. It's made into a slurry for that. I've never thought about it much, but there could be merit to the letting it sit or at least getting it a little wetter than you'd expect. Materials that tend to skin over when drying also tend to take longer to dissolve/activate for the same reasons.
deepakpyro Posted June 1 Author Posted June 1 Thanks, i will try with the acetone+parlon binding. But with the RG and Alcohol, few stars which were pumped immediately after wetting is not Strong as compared to the ones which were pumped last. The batch size is 200gms and while after half way through, i had to re-wet the mix again since they got dried up so fast. I like the idea of making prime slurry @Mumbles is RG is used instead of dextrin in prime (BP/Hot prime) ?
Zumber Posted June 1 Posted June 1 5 hours ago, deepakpyro said: Thanks, i will try with the acetone+parlon binding. But with the RG and Alcohol, few stars which were pumped immediately after wetting is not Strong as compared to the ones which were pumped last. The batch size is 200gms and while after half way through, i had to re-wet the mix again since they got dried up so fast. I like the idea of making prime slurry @Mumbles is RG is used instead of dextrin in prime (BP/Hot prime) ? Already answered in post......binder is red gum and isopropyl alcohol. If there no water there should be no dextrin at all.....
Mumbles Posted June 6 Posted June 6 I probably should have been a little more specific. I was thinking primarily about Lloyd S's Pinball Prime Potassium perchlorate 75 Air float charcoal 15 Red gum 10 Dextrin + 5 (optional) Silicon +5 (optional, any metal or other hot burning components work too) Red gum is a fuel component, but was serving double duty as a binder for me as well. I mix and keep stuff like this around pre-prepared. It very likely had dextrin included as I more often would slurry prime with water or gum arabic solution instead, but I don't recall specifically. This is something I hadn't thought of. I assumed the red gum was doing most of the binding, but maybe there was dextrin around too which contributed. This would have been done with 91% IPA.
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