A week ago I was pondering on the options and risks involved in taking a mold from my clay maquette. Under my post titled "Everlasting Life" I took you through the stages of one option, that being making a plaster waste mold from the clay original. However, due to the small size and fragility of the sculpture, I looked at other possibilities.
One alternative was a gelatin mold and another, a wax mold. Making a wax mold from a clay original is almost a forgotten process. I used it just once twenty years ago. In all of my books on sculpture there is only one brief mention of the technique. There is nothing on the internet...until now!
First a frame is built around the sculpture so as to enable it to be positioned in all directions when applying wax. A clay wall is also built around the base to collect the wax run-off. Metal tell-tale pins are set on the line along which the mold will be separated.
Casting wax is poured and brushed over the clay to a thickness of 1/8" to 1/4". Casting wax is harder than regular modelling wax. Metal and wood reinforcing is added to strengthen the mold and to prevent distortion. The mold is then separated by cutting through the wax with a modelling knife and the clay gently removed.
I used a soldering iron to weld the two halves of the mold back together again. Before pouring the plaster I filled the mold with water to check for leaks. These I stopped with softer modelling wax. The water also helps to determine how much plaster to mix.
I left the plaster to set for two days before gently warming the mold and carefully peeling away the wax.
The above picture shows the plaster cast as it appeared when released from the wax mold. All the detail has been preserved. The separation line can now be filled and other small adjustments made.
The difference in appearance between the clay and plaster reflects the truth of the saying: clay is the life, plaster the death and bronze the resurrection.
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