After many, many hours of exacting work, the wax artisans at the foundry, under the direction of the sculptor have now removed all of the seam lines, air bubbles and tiny imperfections left from the mold and we are left with an exact copy of the clay maquette in wax (this process has to be completed for every statuette cast).
We are now ready for the next stage.
The wax is now cut into component parts and extra lengths of wax tubing or 'gates' added; these provide channels for the molten bronze to enter and the air to escape, lengths of thick fishing line are added at the tips of any extremities which aid the air release.
The main body and approximately 20 smaller parts are then dipped into a revolving drum of silica slurry, and a coat of very fine sand added, the process is repeated each day until the foundry master is happy that the thickness and strength of the new mold is ready for casting; this typically takes 12 to 15 days with 24 hours between each coat to allow for drying.
(The video below shows a model of a Siebe Gorman Diver Statuette going through the same process)
Over the next 12 to 15 days they go from looking like this (you can see the fishing line in this photograph) ...
To this...
And eventually, end up like this
You can see from a broken mold below that the wax is now completely encased by silica. The silica mold can withstand the very high temperatures involved when molten bronze is poured in, but first, we need to get rid of the wax which will leave a void ready for the bronze.
It's time to put the mold and the wax in a furnace so the wax melts and runs out, this gives the process its name, The lost wax casting process.
