High temp Cracking/Fusing under Temp and Load

Does anybody have experience with High Temp Resin being used to mold silicone?

My colleague put it in a carver heated press with less than 100 pounds force (not sure the exact force) holding it together, and the mold cracked all over and looked like it fused together in other areas. The temp was 400 F
We did not have any aluminum cover for the parts. (did not think it necessary for liquid silicone compression molding)

Our silicone needs to heat to at least 400 F to cure.

I have had high temp resin cracking at 130C when it was insufficiently cured and on another instance due to thermal shock(injecting a cold fluid in a cavity).

How are you curing your parts? We have a UV Sterilizing Oven from the formlabs distributor in our area that we have been using set at 60 mins.