For my second project I decided to focus on incorporating colour without the use of coloured glazes. I decided therefore to make a simple bulb shape, cast it in plaster and then apply various techniques to add colour to the surface, oxides, slips, inlays, saggar firing etc.
I made the bulb shape from a solid piece of reclaimed clay, this took a long time to dry, When it had reached a leather-hard state, I used kidneys and saw blades to perfect the surface. The bulb was rounded on one half, but had two flatter surfaces meeting on the other half. It wasn't symmetrical. This would make the mould quite tricky, the process would take most of the day.
I laid the mould down and marked the widest point down each side, this produced a wavy line of dots along the form. I built a wooden surround for the bulb with pieces of wood, leaving at least an inch on either side of the form. I then got clay and built a platform around the form to the wooden box, using the dots to determine the height of the clay platform. Underneath the platform was enough supporting clay to keep the platform firm under the weight of the plaster. I made sure that there were no gaps around the edges or at the corners of the wooden box. To add strength I added clay to the outside of the box at each corner. Time for lunch.
I then mixed up the plaster, and when it had started to thicken slightly I poured it into the box, covering the form by about at least an inch. The plaster hardened quite quickly. I removed the wooden box and turned the mould over so that the new plaster was now the base. I used a surform to get rid of any rough edges. I took a coin to make four notches in the plaster mould, two on either side. I then removed the clay platform and the supporting clay, so that the original solid bulb form was exposed. I used a kidney to get rid of any excess clay and smooth any scratches that had been made during the process so far.
I put the mould back into the wooden box, with the other half of the bulb form now exposed, and painted the surfaces with soft soap, so that the pieces could be separated easily. I started to mix the plaster for the second pour, it was getting quite late most people had gone home. I had not yet filled the corners or sealed the edges of the mould, a basic error. Rob and Louise helped me to fill any gaps at the corners and along the sides, as well as strengthen the corners. Thankfully we were able to do this before the plaster went off, and a waste of materials was averted. As before the corners of the mould were rounded with a surform. The two halves of the mould separated easily, the solid bulb form came out almost in one piece and the mould was left to dry.
This took more than a week, and had to be placed on stilts on top of a kiln for a further week to finally dry out. This probably took a long time because it was a large mould, but also because it was winter and the temperature in the workshop was cooler. It took a lot longer than I expected to make and dry the mould, however once it was complete it was fairly quick to form the basic bulb shapes, ready for the various colour applications.
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