The composition of the metal used for casting is copper, brass and lead (the alloy is called Bronze) with some quantities of silver and load to make it panchadhatu (followed in olden days) Brass is added to reduce the melting temperature of the alloy and also to give a pleasing colour to the finished figure. Small quantity of lead is added just before casting to smoothen the pouring and make the alloy flexible and soft for easy working on it with chisel and hammer.
In normal practice 20 parts by weight of copper is mixed with 5 parts of brass and 1 of lead. These metals are locally available in the form of scraps such as old unserviceable utensils, cuttings, wires, etc., Melting of the alloy is done in ceramic crucibles which are available in the bazaar in any required size.
The furnace generally used for melting is pit type with lining of fire clay brick. A blower is connected to it at one end to blow air. The furnace can either be round or rectangular depending upong the convenience. The blower is either hand operated or power operated with electric motor attached. Coke is used for melting the metal. Tools used for lifting the crucible out of the furnace after melting are called “Tongs” and they have handles about 3 to 4 feet long.
Before actual casting the mould should be properly heated. For this a rough kiln is built around the mould and the fire is kept up by burning firewood and dung cakes till the whole mould becomes cherry red in colour. This hardens the mould and expels trace of moisture. The red hot mould is then buried in the earth upto the mouth of the orifice to keep it firm and upright in position while pouring molten metal into it. It also helps to prevent premature and sudden cooling of the molten metal after filling into the empty chamber caused by removal of wax from the clay mould.
For melting metal scraps are put into the crucible and melted to white heat in the coke furnace. The crucible with metal scraps properly weighed is kept on the follow of the furnace and covered with coke. The Blower is then operated sending air blast into the furnaces to keep the cook in flames. Metal scrap is added to the molten alloy in the crucible periodically until the required quantity of metal is melted.
When the metal is ready melted to proper termperature and the clay mould also heated to cherry red colour the pouring (Casting) is done. A circular ring or rags is invariably placed at the time of pouring around the orifice to prevent metal spilling, the metal is generally poured in then stream. After the mould is completely filled with molten metal the mould is allowed to cool gradually. The cast piece is then recovered by taking out the mould, cutting the binding strip or wire and breaking the clay layers. The stapathy then proceeds on his next work of chiseling and shaping.
For finishing hammers, chisels, files and seevuli are used extensively and for nakasi work finishing nails specially prepared by the stapathy himself are used. With these tools and instruments the stapathy displays his mastery in metal craft. The details of limbs, face, ornaments, dresses, etc., will come to light only when his skilled hands go into actual operation. The process of polishing after the finishing is quite laborious. It is achieved by rubbing fine grade emery paper over the entire surface making it very smooth. The image is cleaned in a solution of tamarind in water, polished and finally washed with soapnut by brushing briskly with the help of wire-brush. This gives a high polish to the metal surface. The polished figure is then oxidized b lack or brown according to the requirement to give attractive appearance.
In normal practice 20 parts by weight of copper is mixed with 5 parts of brass and 1 of lead. These metals are locally available in the form of scraps such as old unserviceable utensils, cuttings, wires, etc., Melting of the alloy is done in ceramic crucibles which are available in the bazaar in any required size.
The furnace generally used for melting is pit type with lining of fire clay brick. A blower is connected to it at one end to blow air. The furnace can either be round or rectangular depending upong the convenience. The blower is either hand operated or power operated with electric motor attached. Coke is used for melting the metal. Tools used for lifting the crucible out of the furnace after melting are called “Tongs” and they have handles about 3 to 4 feet long.
Before actual casting the mould should be properly heated. For this a rough kiln is built around the mould and the fire is kept up by burning firewood and dung cakes till the whole mould becomes cherry red in colour. This hardens the mould and expels trace of moisture. The red hot mould is then buried in the earth upto the mouth of the orifice to keep it firm and upright in position while pouring molten metal into it. It also helps to prevent premature and sudden cooling of the molten metal after filling into the empty chamber caused by removal of wax from the clay mould.
For melting metal scraps are put into the crucible and melted to white heat in the coke furnace. The crucible with metal scraps properly weighed is kept on the follow of the furnace and covered with coke. The Blower is then operated sending air blast into the furnaces to keep the cook in flames. Metal scrap is added to the molten alloy in the crucible periodically until the required quantity of metal is melted.
When the metal is ready melted to proper termperature and the clay mould also heated to cherry red colour the pouring (Casting) is done. A circular ring or rags is invariably placed at the time of pouring around the orifice to prevent metal spilling, the metal is generally poured in then stream. After the mould is completely filled with molten metal the mould is allowed to cool gradually. The cast piece is then recovered by taking out the mould, cutting the binding strip or wire and breaking the clay layers. The stapathy then proceeds on his next work of chiseling and shaping.
For finishing hammers, chisels, files and seevuli are used extensively and for nakasi work finishing nails specially prepared by the stapathy himself are used. With these tools and instruments the stapathy displays his mastery in metal craft. The details of limbs, face, ornaments, dresses, etc., will come to light only when his skilled hands go into actual operation. The process of polishing after the finishing is quite laborious. It is achieved by rubbing fine grade emery paper over the entire surface making it very smooth. The image is cleaned in a solution of tamarind in water, polished and finally washed with soapnut by brushing briskly with the help of wire-brush. This gives a high polish to the metal surface. The polished figure is then oxidized b lack or brown according to the requirement to give attractive appearance.
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