If you want to shrink a model effectively without too much loss of
detail, the best way to do so is to use heat cured red silicone from
the Contenti Co. ( 800-343-3364) What you do is set your vulcanizer
for 375 oF and vulcanize for 15 minutes per 1/4 inch of thickness.
At this temp , you should achieve about a 10 to 12% shrinkage per
mold made… if you include casting the first shrinkage and cleaning
it up a bit, you will be very close to 30 % … and the final mold
will work well in production… this same rubber is normally used at
325 oF for normal standard molds… Quenching the hot mold frame and
mold into cold water will help to increase the shrinkage slightly.
Contenti’s moldex rubber is the least expensive heat cured silicone
based rubber on the market .
I have used the Reduce it compounds and have found that much work
will be needed on the model afterwards and have not had much use for
the material . I could usually carve a better model by hand faster
than using this material and then going through all the clean up
Hope this helps. Daniel Grandi
We do casting, finishing , mold making , cnc model work and a whole
lot more for designers, stores and people in the trade. Please