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[TK 109]

I posted this question a while back, and I think we determined it was feesible. This time, though, I have a mold, and an idea.

Ok, Here's the situation...

I have some positive plaster molds (stormtrooper helmet parts). That's cool and all, but they're going to crack, because it's just regular plaster of paris. I was thinking of forming the pieces, and backfilling the pulled plastic with some sort of RTV silicon, resin, polyurithane, SOMETHING that would hold up to the vacuum, but something flexible so that pulling and releasing the mold would be easy. I know for a fact that most armor makers out there made their molds out of a form of RTV silicon (the face, the cap and back as one piece, and the ears), so that they last longer, and release easier.

I would need somthing, preferably, that I could pick up at a store that I could look up in the yellow pages. Something also that's relatively cheap. I'm mainly aiming for a form of DENSE yet FLEXIBLE RTV Silicon.

Hopefully, you guys can help me find something. If you think of something, let me know. The first thing tha comes to my mind is: Hey, Jim, what about that purple RTV silicon you use to cast those e-11 parts in your videos? Would it be dense enough to hold up to forming?
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-Alex

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[jegner]

I see where you are going with this, and having a vac-mold that is rigid enough to hold it's shape during forming, and yet flexible enough to release the part without breaking might be the job of a polyurethane rubber. It wold be cheaper than silicone, would hold up to the demolding process, and should be heat resistant enough to work for a long time.

Trouble is, you would have to make a negative mold of your plaster part, then cast the polyurethane rubber in this mold. Expensive to get you to the final mold, but it might be worth it.

www.smooth-on.com has a product called Vytaflex that might be perfect for this.

http://www.smooth-on.com/Urethane-Rubber-an/c6_1117_1142/index.html

Another idea might be to use some rubber used for a poor-man's 'Hyperfirm' rubber from http://www.jgreer.com/concrete%20molding.htm

Just some ideas.

[TK 109]

Wow! Thanks, Jim! I'll have to look into that stuff.
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-Alex

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