Foam latex question

Troy Mccombs

I recently did a foam run where I filled three ultracal molds and placed them in my makeshift oven. One mold was small ( a forehead prosthetic). The other two were face molds, about the same size. My oven circulates air. When I demolded the three molds, the smallest mold (forehead) turned out well and was cured. One of the face pieces turned out well, too, but the third felt (soupy) in the middle, as if it hadn't fully cured. Does anyone know why this may have happened ? Because I ran them all at the same time (2 hours and forty minutes). I don't understand why 2 turned out and one didn't. Also, once a prosthetic is demolded and not completely cured, can I cure it after the fact?

Chris Ellerby

There are a lot of factors that can cause different molds to bake slower or faster.    The mass of the mold and the thickness of the mold material can act as a heat sink, making a mold take longer to heat up or cool down.  The thickness of the foam can also impact time, as thinner pieces will bake faster than pieces with a larger volume of foam.  

One thing you can do as you determine how long a mold takes to bake at a specific temperature is write that time/temp on the mold so you know for next time.

Ovens can also have zones where the air circulates more or less depending on how multiple molds are positioned in relation to each other, the heat sources, and airflow.

You can try putting the prosthetic back in and baking it a bit longer, though demolding and handling may deform it a bit, and the foam can collapse a bit.

/Chris