worked great. I did have an issue with the mold I had swelling more on one side that the other so it curved a bit. But I was able to get it where I needed. I have a stone going into casting of a pendant. The stone was a tiny bit big.
Any way to make a mold bigger???
- Thread starter MattMunson
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If only this trick worked on my penis. I'd go make movies.
Just smash it with a hammer. it'll get bigger. Whatever you do dont stick it in a vise.
which method did you use? pictures?
macropod80
Active Member
I did manage this successfully years ago with tin-cure silicone moulds sitting in shellite. The mould starts to swell almost immediately but takes a while to settle down to uniform, even expansion. It takes several hours to get to around 120% or so (I once waited overnight to get to about 150%). But it's tricky: as soon as you take it out of the shellite, it starts to shrink again as the shellite evaporates, and the shellite can interfere with your casting material. Also the silicone mould becomes fragile and prone to tearing as you remove the casting. And controlling the exact amount of expansion is difficult.
In theory you could expand your mould; do a casting; then mould that and expand the new mould - and so on to get as big as you like. (I've also read - but haven't tried - that you can do the reverse by adding shellite to the mixed silicone before pouring it over your subject. Then once it cures you remove the original and as the shellite evaporates, the mould shrinks so you can produce reduced castings.)
It's easiest with simple, open-topped moulds.
In theory you could expand your mould; do a casting; then mould that and expand the new mould - and so on to get as big as you like. (I've also read - but haven't tried - that you can do the reverse by adding shellite to the mixed silicone before pouring it over your subject. Then once it cures you remove the original and as the shellite evaporates, the mould shrinks so you can produce reduced castings.)
It's easiest with simple, open-topped moulds.
As Adam said; back at ILM we "grew" a coin to be quite large by soaking a silicone casting in gasoline, and then molding the swollen piece.
We repeated the process several times to get it really big. The silicone expands only so far before it becomes too fragile to handle.
A few years later we enlarged a silicone mold of a puppet using diesel instead of gasoline. It worked great, but stunk worse than the gasoline. The thinking was that the diesel fuel would evaporate slower from the mold - giving us more time to get a good casting out of it. Gasoline evaporates faster than diesel. I think we soaked that mold for 2-3 days. It was a large mold, and we wanted the diesel to soak through it evenly.
We repeated the process several times to get it really big. The silicone expands only so far before it becomes too fragile to handle.
A few years later we enlarged a silicone mold of a puppet using diesel instead of gasoline. It worked great, but stunk worse than the gasoline. The thinking was that the diesel fuel would evaporate slower from the mold - giving us more time to get a good casting out of it. Gasoline evaporates faster than diesel. I think we soaked that mold for 2-3 days. It was a large mold, and we wanted the diesel to soak through it evenly.
