Bake 'dry' ultracal 30 life casts and molds prior to foam latex?

Hello, I was wondering if I need to bake my ultracal lifecast and mold prior to running foam latex? I recently found an online fx book that suggested that plaster pieces, including those made with ultracal 30, retain some water until the water is 'baked out', so to speak, and that if the moisture is not dealt with prior to running foam latex it can steam the foam during the cure and ruin it. Is this true? If so any general guidelines on how long I need to bake my pieces? Thanks in advance! Caterina 


  • Greetings Caterina,

    If your stone (Ultracal) mold still contains moisture it can generate steam that can create pockets or "second skin" defects in a foam latex piece.

    How long you should bake your mold depends on how old it is (over time they naturally lose moisture) and how dense it is, as larger/thicker molds hold more moisture and dry slower.

    One source I found suggests baking molds for 30 minutes in a convection oven at 180°F.  But there is no reason you could not use a lower temperature for a longer period of time, or even just leave them out in the sun to dry naturally if you have the time and low enough humidity.

    Best of luck!


  • Thank you soooo much Chris, I can't tell you how much I appreciate the help! My lifecast and mold are both brand new, so to speak, so I'll pop them in my foam latex oven at a low temp for 30+ minutes. THANK YOU AGAIN!! 

  • My pleasure, and happy baking!

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