This part is dedicated to prototype creation. The prototype is an early sample (or model) of an object built to be replicated. Its realization takes place thanks to the traditional moulding process and, above all, the brand-new 3D printing.
The more complex molds, made of two or more pieces of plaster that fit together, are most often used with slip to produce hollow, slip cast objects such as vases. Our model can be an existing object or an object that we’ve made using clay or many other materials as wood, plastic, metal ABS etc. It’s very important model’s diagnosis: mold must release easily from the model. To make a good diagnosis, it’s necessary to understand the concept of undercuts, indented areas in the model that can make it impossible to separate the model from the hardened plaster mold.
If the object has no undercuts, it’s easy to pour plaster around this shape and lift the mold straight up from the model when plaster hardened.
But if the object has undercuts, no matter how we positioned it, we have to make more piece mold, each piece of which could be drawn away from one portion of the model.
To use the moldsconsisting on two or more pieces we have to aplly a release to the face of each mold piece and then bind them together. Now we can pour liquid slip into the assembled mold, through an hole in it’s top, filling the cavity completely. Plaster absorbs moisture from the slip. We wait for few minutes and then we pour liquid’s excess out.
When slip inside the mold is firm enough to support itself without mold, we separate the pieces.