After building up a pinkey's width of flash coat on your sculpture, you have the option to apply a 1:10 ratio of oil soap to water with a touch of paint to the cast. This will allow for an easier time demolding because as you demold the thicker coat of plaster will break off easier and you can then see how close you are to the cast. When applying this solution, be sure to keep 2 inches away from edges as the solution will make the mold weaker and the edges will be more likely to break. I did not have access to anything to color the solution hence why you cannot see it here.
