RPF PREMIUM MEMBER
I assume the shrinking occurs after the rubber has set? So you remove the donor part and then it's shrinkydink time?
If my calculations are correct (I've always wanted to say that), then a mold that shrinks 50% in volume would yield a part that is 79.37% of the original in physical dimension. Does this seem right? I need to find that formula and see what I come up with using that. The original post seems to have been taken down.I have a technique for making silicone molds that shrink. So far I have tested a ration of 50:50 Silicone to Naptha that really does shrink 50% of volume. The actual ration of dimensional length is some sort of complicated math formula that I haven't figured out yet. But it is something to consider as you go forward with this venture.
OK. I have just a few questions then:The detail should hold just fine. An they will look sharper as they reduce in size. The only real tricks are to make sure your mold are air tight while they set up and that you are VERY carefull getting your pattern out of the rubber. the "thinned" silicone is like jello untill the naptha evaporates.
...You there Cobywan?OK. I have just a few questions then:
1) What do you mean when you say, "make sure your mold are air tight while they set up?"
2) Do you give the rubber the same amount of time to set as you normally would (without the Naptha)?
3) How long should I wait for the Naptha to evaporate completely, or as close as it can get?
Thanks, Coby.1. The mold needs to have a lid or be in a small container with a lid. You need to prevent evaporation while the rubber cures. I build my boxes out of styrene or acrylic and after teh rubber is poured I slap a plate over the top.
2. The set up times are the same.
3. You can tell it's done when the smell of naptha is gone. It shouldn't take more than a day to evaporate out.