The cast of a teacup that I've recently made from plaster of Paris has completely dried up. To make the cups from the mould you need to have the slip and stir it well until it's of equal consistency. Have a jug, a bucket and wooden planks called guides near by. Place the guides on top of the bucket with a space where the mould hole is. Dip the jug into the slip, with a good amount and pour into the mould without spilling over. After this wait approximately four to five minutes, the size of mould and how much water is in the slip will estimate how much time to wait. When all that's done the next stage is turn the mould upside down and over the bucket with the guides supporting it. Leave like this for over 10 minutes to drain the excess slip then turn it back over and wait for the slip in the mould to dry more. Lastly is just taking the cup out and neatening it with a grater and sea sponge and the piece is complete.