Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!


Sealing hydrocal mold?

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.


  • Chris EllerbyChris Ellerby Los Angeles Admin
    Hi Tanuki,

    Here is the page for FlexFoam-It

    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.

  • My bigger issue is what to seal the hydrocal with or if I need to 
  • Chris EllerbyChris Ellerby Los Angeles 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.


Sign In or Register to comment.