Sealing hydrocal mold?
in Sculpture
So I am working within a tight budget which is why I'm not using a silicone mold. I am going to be casting the part out of Smooth-on's flex-it foam IV. I need to seal my hydrocal mold but can't seem to find out what the best thing to seal it with. I've seen mold soap used but that was for making silicone casts not urethane. I need to call smooth-on to see if the Ease Release 200 will work with the urethane but what do I use to seal the hydrocal that will work with a release agent like ease release 200. Or is there something better I can use as a release. Would Meguiars mold release wax work? Could that seal it and be a release? What about the Jonhson's wax? Thank you.
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Best Answer
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Chris Ellerby
Admin
The release agent should seal the surface. Your first run with the mold may just require a bit more release, as the Hydrocal may soak up a bit.
I would also suggest using Ultracal rather than Hydrocal in the future. Hydrocal is made to be slightly more porous to wick moisture away from a casting. This is a great property when making something like a latex mask, where that property helps you to form a skin along the surface of the mold. But that also means it is more brittle. Ultracal is a bit more dense, so it is stronger.
/Chris
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Answers
Here is the page for FlexFoam-It
https://www.smooth-on.com/products/flexfoam-it-v/
They recommend recommend Ease Release 2831 to release their urethane foam.
You are right to be cautions, as some release agents (like those made of silicone) will cause the foam to collapse.
I believe a wax based release would work, but I have not tried using wax with FlexFoam-It, so I can't say for sure.
/Chris