Questions about casting and joining clear resin

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Questions about casting and joining clear resin

Post by No_6 » Thu Mar 15, 2012 2:08 pm

Heya. I got it into my hand to do a sculpt of the Glass Hand from "Demon With a Glass Hand" but am trying to figure out the best way of doing things so that I can add lights and the inner structure. Wondering if y'all might have some good ideas.

First, it seems like the way to get the effect closest to the show is to cast the palm, pinky and thumb as a single piece, pre-build all the internal electronics and then suspend it in the mold during casting. This raises some questions as to what to do about the speaker. It protrudes out of the 'glass' palm. So if non-functional, I could just sculpt it and then paint the resin. If I want it to be functional.... then I'm not sure, because weather a hole is part of the sculpt or it has to be drilled out after, it creates problems with the electronics during casting.

I figure the removable fingers should be cast separately, with the wires and structure inserted into the mold during casting.

But I don't know... How about this, ALL of the fingers would be cast (solid) separately. The palm sculpt could be cut in half and then hollowed out to fit the electronics. But if done this way, the seam would be very visible when joined, which kind of bothers me. Also, being mostly hollow, it wouldn't have the same glasslike qualities the prop had. After the electronics were installed, could the hollow space then be filled with resin, or would that look weird?

I was figuring on using Smooth-On Crystal Clear 202. Would something with a longer pot/cure time be better in terms of getting pieces with no bubbles in it?

Lastly, I was thinking of using Apoxy Sculpt over balsa for the sculpt. Would this be strong enough to make multiple molds from? Or should I consider using a different material? The only surface detail would be the raised rings around the fingers (the GH thread on the RFP forum speculates that the original mold was made from taking a pair of rubber work gloves and turning them inside-out, which would explain the rings).
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Post by Ziz » Thu Mar 15, 2012 5:18 pm

I haven't fooled with clear resin yet but when I make parts that will end up having holes in them - the Work Bee, for example - I just fill the hole in the master with a piece of sheet plastic for casting. The builder then just has to remove the filler piece as part of the construction process. You could do something like that with your design - make the hole for the speaker integrated into the sculpt so that the lighting components are designed around it to begin with. Then all you need to do is remove the "plug" from the center hole and install your speaker.

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Re: Questions about casting and joining clear resin

Post by kenno3 » Sat Apr 14, 2012 5:01 am

No_6 wrote: I was figuring on using Smooth-On Crystal Clear 202. Would something with a longer pot/cure time be better in terms of getting pieces with no bubbles in it?
A longer cure time could help the bubbles rise before the liquid gels. If it's a small part you can pick out the bubbles with a toothpic or hold a blow dryer over the surface to pop the bubbles.

But that didnt work for my part which was a complex and deep mold, so I bought a pressure pot and pressure cast at about 35 psi which crushes the bubbles, then the liquid gels and cures, then the bubbles cant be seen once you take the mold out of the pressure pot. I get perfectly clear castings this way, so it was worth it to me, to buy the pot.

I used Easy Cast clear epoxy. It's easy to pour, it has a long pot life, but ive had it cure soft sometimes, othertimes hard. You need a perfect 1 to 1 mix ratio. ... epoxy.html

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