RUPERT THORNELOE: Base Mould Part 5 Rubber

Once the rubber had cured for at least 24 hours I removed the clay pour cups from the top of the plaster jacket. The excess rubber was cut back to the plaster level on both sides and it was ready to open.

Carefully prising the plaster halves apart revealed the rubber inside. Both halves of the jacket are removed to reveal the bare rubber. I trimmed off the rubber that had risen up the air holes and the flash of rubber from between the two plaster halves.

Below: Excess rubber was trimmed from around the keys and once the rubber was taken of the base pattern I set about removing the letters that had become trapped in the rubber surface. The rubber around the letters was also trimmed to remove any flashes .

Below: Here you can see the extra rubber that was created on the back to act as a location key, this is also the point that I wanted to split the rubber to allow for easier removal of the wax/plaster/casting material that will be in the mould later. It is important to cut this rubber in a zigzag fashion so that it locates in the right position when placed back in the plaster jacket.