So I tried it experimentally with a two peice muskie size crank bait mold I designed with the lip part of the mold to be poured in, rather than added separately afterwards. I submerged it in mineral spirits overnight. It expanded alright, I'd say a good 10%. The top half of the mold warped a bit at the outside, but I think that can be overcome by clamping the mold together between two peices of plexiglass or similar (which I alays do). I'm not sure if the lure edges line up well, yet, but the problem is the slot area for the lip expanded/warped in on the slot closing the lip area; I can pull it back to the right size, but I cannot keep it that way when I put the mold halves together for pouring. (I'd attach picture to show, but I don't know how to do that.) Anyway, if you are thinking about enlargening a two peice mold by soaking in mineral spirits, you may want to think again and try something else. I'm not saying it can not be done; it would defineitly take more precautions, attention, and work than I employed though.