This was my first ever attempt at mould making and the biggest challenge was to predict how big the final cup will turn out to be. From start to finish, the cup goes through three stages of shrinkage meaning that I had to accommodate by making a larger form to begin with.

First, the original form was sculpted from clay and bisque fired. During the firing, the clay undergoes a chemical reaction to become ceramic and shrinks in the process. The fired cup is then used to create a four-part plaster mould. Next, each cup slip-cast from the mould goes through the same bisque firing process and shrinks again. Lastly, the bisqued, slip-cast cup is dipped in glaze and undergoes a glaze firing that vitrifies the ceramic material, making it non-porous and food safe. Pictured below is a comparison between a bisqued slip-cast cup (left) and a glaze-fired cup that shows the third and final stage of shrinkage.