leia
Freakzoid
Hi guys.
I have a tendency to sculpt slightly too large, which is very frustrating. I wanted to share the method I use to shrink my molds. It is slow, but it is rather effective. Also, you will need a gram scale for this method.
I add mineral spirits to the silicone. As the mineral spirits evaporate, the mold shrinks in proportion to the percentage of mineral spirits you added. I'm guessing that it varies by brand, but it ends up being...
(your mixed weight of silicone) x 50% = the weight of the mineral spirits you can add for AROUND 15% shrinkage
More than 50% will cause some negative effects in your silicone, from what I've read. The most I've done in around 30%. Anyway, you can mix around the proportions to get the shrinkage that you want. (I generally do around 30% by default, then just pour a text cast every few days until it's the size I want, then I finish up the properly sized cast and mold that).
For example, this is a Silva head that I wanted to shrink before sculpting his hair.
This was the cast I ended up finishing (about 3 days of letting the mold shrink, sped up a bit by putting it on a candle warmer):
But this is how small the mold got after a few weeks:
If you need really big shrinkage, you could always mold it more than once.
You can also speed up the shrinking process by popping it in your oven for a few hours at just over 100 degrees. My oven doesn't go that low and my housemate won't tolerate the smell, so I just bought a little candle warmer and I plug it in down in the basement. I flip the mold every half hour or so and let it go for a few hours at a time.
You can use odorless mineral spirits, but the mold I'm currently shrinking seems to be having some light cure inhibition with the resin. It didn't happen with the normal spirits, but the surface of my cast of Bond is a bit tacky and shiny. (Though it's firmed up after sitting on my desk for a few hours.) I'm not sure if it's because it's a bit humid today too, but at this point I recommend normal mineral spirits if you have a well-ventilated work area or place you can leave your mold to shrink.
I hope this is helpful!
I have a tendency to sculpt slightly too large, which is very frustrating. I wanted to share the method I use to shrink my molds. It is slow, but it is rather effective. Also, you will need a gram scale for this method.
I add mineral spirits to the silicone. As the mineral spirits evaporate, the mold shrinks in proportion to the percentage of mineral spirits you added. I'm guessing that it varies by brand, but it ends up being...
(your mixed weight of silicone) x 50% = the weight of the mineral spirits you can add for AROUND 15% shrinkage
More than 50% will cause some negative effects in your silicone, from what I've read. The most I've done in around 30%. Anyway, you can mix around the proportions to get the shrinkage that you want. (I generally do around 30% by default, then just pour a text cast every few days until it's the size I want, then I finish up the properly sized cast and mold that).
For example, this is a Silva head that I wanted to shrink before sculpting his hair.
This was the cast I ended up finishing (about 3 days of letting the mold shrink, sped up a bit by putting it on a candle warmer):
But this is how small the mold got after a few weeks:
If you need really big shrinkage, you could always mold it more than once.
You can also speed up the shrinking process by popping it in your oven for a few hours at just over 100 degrees. My oven doesn't go that low and my housemate won't tolerate the smell, so I just bought a little candle warmer and I plug it in down in the basement. I flip the mold every half hour or so and let it go for a few hours at a time.
You can use odorless mineral spirits, but the mold I'm currently shrinking seems to be having some light cure inhibition with the resin. It didn't happen with the normal spirits, but the surface of my cast of Bond is a bit tacky and shiny. (Though it's firmed up after sitting on my desk for a few hours.) I'm not sure if it's because it's a bit humid today too, but at this point I recommend normal mineral spirits if you have a well-ventilated work area or place you can leave your mold to shrink.
I hope this is helpful!
