Casting in plaster allows for more detailed figures to be designed. The process is simple and quick and pupils can develop their own mould using this process.
First cut a piece of MDF 50mm x 50mm square. Place masking tape around the edge of the MDF to create a reservoir to hold the plaster. Within the reservoir and on the base of the MDF place a square of the same size of Clingfilm. The purpose of this is to act as a barrier between the plaster and the MDF so that the two will easily separate.
Place the shape you wish to cast in the centre of the mould on the top of the Clingfilm.
Mix the plaster, Moulding Powder for Model Making is available from model shops. 1kg will make around 10 moulds which have a multi-cast use. The setting time of the plaster is 10-15 minutes maximum.
Once the plaster has set the Clingfilm allows for the separation of the MDF from the plaster without any difficulty.
To release the template from the plaster cut a sprue hole from the top edge of the plaster mould down to the template. The template can, with care, be removed from the mould using a bradawl or similar tool. (The sprue is effectively a funnel to allow the liquid metal to run into the mould).
Even though the outside surface of the mould may be uneven, using the Flamefast spring clamps the mould can easily be held in place for a successful pour.
Consider the design. For this design air exit holes were needed at the tip of each ear so that any trapped air can escape and allow the metal to flow into each ear.
