Mold-Making Theory: Is It Hard or Is It Soft?
The first step in any mold-making project is to consider what you want your cast item to be used for. Do you want a solid skull as a base for building up a zombie face with clay and maché? Maybe you want a squishy dismembered hand that looks and feels lifelike. You have to consider what you want your casting to be. You will have to build your mold to the casting material you want to use. This is not absolute, but generally you won't be able to make a hard casting and a soft casting from the same mold. There are ways to try to game the system, but they are compromises to quality and/or ease of use. Hard molds make soft castings ∞ Soft molds make hard castings If you want to make a hard, bone-like skull, you will need a soft, flesh-like mold. Inversely, if you want to make a soft, flesh-like hand, you will need to make a hard mold. Why? Friction. Why does friction matter? When you pour casting material into a mold, you are making a copy of that mold right down to the molecular level...