Metal Icons of Thanjavur
When the wax model is completed, Sthapathi fixes the image on a wax base, which is attached to a wax rod ending in a funnel-shaped flange. This is a runner, which serves as an ingress for pouring molten metal and also as an ingress for draining out the molten wax. Through the wax rods, metal is poured into various parts of the image. This completes the preparation of the model. For making a clay mould out of a wax model a process called as “Mankattal” is performed. For the first three recasting, fine loam is ground into a paste with charred husk and cow dung. The Sthapathi covers the entire wax model with this paste, which for the first coating, is applied in a semi-solution form and is then allowed to dry. This process is repeated three-four times till a fine even layer of loam is spread all over the surface. This is a clay surface, which comes in contact with molten metal.
Encasing wax model in clay:
The model is encased in layers of coarser clay. Three successive layers of such clay are applied to the model, with each layer becoming coarser and bulkier than the one before. Each layer should be allowed to dry completely before coating the next layer. After the second coating, fine steel is wound around the entire piece. This wax orifice serves both as a runner and a vent.
Draining off the wax:
The Sthapathi, heats the mould over a drafted ground surface called ‘Ulai’, when the wax in the mould melts and runs out. The Sthapathi then collects the wax and weighs them to ascertain the quality of metal required for the operation.
The next step in the craft sequence is pouring.
