Paul took us through a couple of traditional mold making techniques this week. The first was 'pressed clay'. This is what you do:
- decide what you want to make - a plaque? a model of something? perhaps do a drawing to sketch out some ideas. We were encouraged to find a range of objects with different textures and use this workshop to experiment and play with the possibilities.
- prepare the surface of the clay which is being used to press the objects into.
- Paul pressed a few objects into the clay...
- then built a solid wall of clay around the area designated for the plaster.
- Mix the plaster - water first! For the size of the clay moulds we were using about 5cms of water in a regular bucket was plenty; sprinkle the dry plaster into the water quite quickly; when 'islands' of plaster start to form slow down the addition of the plaster; you want about 50% plaster and 50% water visible in the bucket; stir the plaster/water mix quickly with your hand to get the lumps out; when it is smooth and the consistency of cream (not whipped!) it is ready to pour into the clay mould
|the clay mold with 'walls' around the imprint, filled with plaster|
|If you are making a plaque and want to hang it on a wall place a wire hanger; make loops on the wire to provide something for the plaster to 'grip' onto|
- leave the plaster to set for at least 40 minutes. If a fingernail scraped across the plaster leaves a deep indentation it is not ready to be released from the mold.
- when the plaster is hard, peel the clay away from the plaster model.
- wash the plaster model with water and brush to remove and clay left in deep indentations
- leave the plaster model to dry - prop it up so that it dries underneath evenly
Here is my first effort. This technique provides a detailed casting and is easy and cheap, but one off. The clay is peeled away from the plaster when it has set so you lose the original mold.