N.C.A.D. Diploma in Art & Design
Sculptural Processes - Clay
Creating a Clay Mould / Clay Sculpture
The below process is the simplest method for creating a clay mould. Again, the use of random materials and found objects can be a nice feature to indent within your design on the clay (eg. Leaves and foliage).
1. Mould/shape the design that you wish to create into the clay (using buff air drying clay). This clay can be used either on its own to create a sculpture, or, to create a clay mould for plaster setting.
I had a spider figure which I pushed into the clay and thus created its imprint within the clay block that I was using. Another simple imprint that I created was by using a leaf and applying pressure to it, against the clay, in order to leave its outline in the clay.
You could now oven bake your clay if you wished to to create a permanent mould, or, if you have now completed your clay model piece. A useful guideline on oven bake times for polymer clay can be found here. Most polymer or oven-based clays will harden after they are cooked at 265 °F (129 °C) to 275 °F (135 °C) for 15 minutes per 1⁄4 inch (6.4 mm) of thickness. You could also use self hardening clay - in this case the clay will harden itself over the course of a few days. Fine art clay is similar to self hardening except they use high-quality clay and add water only.
2. Now that your mould has been created with the clay, you can proceed to prepare the mixing plaster (fine casting plaster) in order to pour this into your mould and thus create the model. Mix the plaster directly into cold water (poor water in first).
3. Mix the plaster and water for a few mins.
4. Poor the plaster/water mix into the clay mould.
5. Leave to set (include netting etc. in the middle of the plaster in order to make a stronger base).
6. Carefully separate the mould from the plaster when it’s set (see below pics of the finished spider and leave).
(Tip: WD-40 oil - you could use this spray on your clay model to help the plaster not to stick.)
Setting objects in your clay to create sculpture
After mixing your plaster with water, you could then cover found materials and objects (such as the twigs I used in the below pictures) in order to create sculptural work. I placed the twigs into bottle caps and poured the plaster into the bottle cap (with the twig propped inside of the cap) and let set.