Bertrand Bellaize, 18 February 2020
Tribal Dokra art: casting and finishing the brass statue
Once the wax work is finished, it is again covered with a mixture of clay, based on river sand. As soon as the drying is finished, a new layer is applied to reinforce the structure of the whole before firing. Holes for the flow of wax are also made at this stage. A final layer from a clay-rice husk mixture is applied to solidify the whole: fire losses are significant, the result is far from guaranteed every time: clay that splits, gas créating breaches...
The copper alloy used is similar to brass as we know it in Europe, namely 70 to 95% copper for 5 to 30% zinc. The Dokras are supplied in brass with pieces of usual broken objects: kitchen utensils, plumbing, etc. the alloy is therefore never equivalent from one production to another. The calculation of the necessary quantity of metal is made approximately by experience.
At this point in the process, two techniques for casting brass (or copper alloy) are used depending on the region.
Once the wax work is finished, it is again covered with a mixture of clay, based on river sand. As soon as the drying is finished, a new layer is applied to reinforce the structure of the whole before setting it on fire. Holes for the flow of wax are also made at this stage. A final layer from a clay-rice husk mixture is applied to solidify the whole: fire losses are significant, the result is far from guaranteed every time: clay that splits, gas that creates ... breaches.
The copper alloy used is similar to brass as we know it in Europe, namely 70 to 95% copper for 5 to 30% zinc. The Dokras are supplied in brass with pieces of usual broken objects: kitchen utensils, plumbing, etc. the alloy is therefore never equivalent from one production to another. The calculation of the necessary quantity of metal is made approximately by experience.
At this point in the process, two techniques for casting brass (or copper alloy) are used depending on the region.
The first method is to cast the alloy using the wax discharge holes which will be widened by making a funnel. The second consists in the manufacture of a clay pocket which will be added to the modeling and which will contain the metal.
In the first case, two fireplaces can be lit, the first one will be used to heat the modeling, raising it to the right temperature for the wax to flow. In the other hearth, the mixture of metals will be heated (sometimes a little salt is added to speed up the process) 2 to 3 hours up to 400°C: here again everything is experimental and the know-how of the artists plays a key role in determining the right temperature of flow of the wax, to pour the molten metal (for example the color of the flames above the melting ...).
In the second case, the modeling is put entirely in the fire, the skill of the artist will be to determine when the metal will have flowed: to do this, using pliers, he lifts and shakes at regular intervals the modeling to know the fluidity of the brass.
In some villages, a communal oven is used for all the villagers (West Bengal): it is lit a few times a month; elsewhere each family has its own home, usually a hole in the ground outside the house under an awning to protect itself from the sun or the monsoon rain, which it uses as needed.
It is important to know that the Dokras work in tongues, loincloths, tee-shirts without any protection, with the risk of burning themselves but also with the discomforts linked to the heat of the brazier. The utensils are rudimentary, the metal is melted in coarse crucibles which are grasped by pliers and poured into the modling: the losses are important (15-20%) even if the copper alloy is then recovered and reused in the next manufacturing process.
Once the casting is completed, the modling is removed from the heat to cool, sprayed with water, then coarsely demolded. Once completely cooled, the clay matrix which has hardened considerably in contact with fire is first removed using a small pointed hammer. Then comes a long work of cleaning all the small clay impurities which adhere in the many details of the sculpture using a wire brush and a punch. At this stage, many sculptures are eliminated because of their faults: air pockets which prevented the flow of metal to the ends of the sculpture, cracks that appeared on drying, imperfections during the production in wax causing a break (on fragile parts such as fingers, headdress, jewelry, etc.) ...
The last step is polishing, which is now done mechanically.
The sculpture is now ready to be sold either on a local market or to a wholesaler who will distribute it throughout India.
The copper alloy
The copper alloy used is similar to brass as we know it in Europe, namely 70 to 95% copper for 5 to 30% zinc. The Dokras are supplied in brass with pieces of usual broken objects: kitchen utensils, plumbing, etc. the alloy is therefore never equivalent from one production to another. The calculation of the necessary quantity of metal is made approximately by experience.
At this point in the process, two techniques for casting brass (or copper alloy) are used depending on the region.
The casting
Once the wax work is finished, it is again covered with a mixture of clay, based on river sand. As soon as the drying is finished, a new layer is applied to reinforce the structure of the whole before setting it on fire. Holes for the flow of wax are also made at this stage. A final layer from a clay-rice husk mixture is applied to solidify the whole: fire losses are significant, the result is far from guaranteed every time: clay that splits, gas that creates ... breaches.
The copper alloy
The copper alloy used is similar to brass as we know it in Europe, namely 70 to 95% copper for 5 to 30% zinc. The Dokras are supplied in brass with pieces of usual broken objects: kitchen utensils, plumbing, etc. the alloy is therefore never equivalent from one production to another. The calculation of the necessary quantity of metal is made approximately by experience.
At this point in the process, two techniques for casting brass (or copper alloy) are used depending on the region.
The casting
The first method is to cast the alloy using the wax discharge holes which will be widened by making a funnel. The second consists in the manufacture of a clay pocket which will be added to the modeling and which will contain the metal.
In the first case, two fireplaces can be lit, the first one will be used to heat the modeling, raising it to the right temperature for the wax to flow. In the other hearth, the mixture of metals will be heated (sometimes a little salt is added to speed up the process) 2 to 3 hours up to 400°C: here again everything is experimental and the know-how of the artists plays a key role in determining the right temperature of flow of the wax, to pour the molten metal (for example the color of the flames above the melting ...).
In the second case, the modeling is put entirely in the fire, the skill of the artist will be to determine when the metal will have flowed: to do this, using pliers, he lifts and shakes at regular intervals the modeling to know the fluidity of the brass.
The hearth
In some villages, a communal oven is used for all the villagers (West Bengal): it is lit a few times a month; elsewhere each family has its own home, usually a hole in the ground outside the house under an awning to protect itself from the sun or the monsoon rain, which it uses as needed.
It is important to know that the Dokras work in tongues, loincloths, tee-shirts without any protection, with the risk of burning themselves but also with the discomforts linked to the heat of the brazier. The utensils are rudimentary, the metal is melted in coarse crucibles which are grasped by pliers and poured into the modling: the losses are important (15-20%) even if the copper alloy is then recovered and reused in the next manufacturing process.
Demoulding
Once the casting is completed, the modling is removed from the heat to cool, sprayed with water, then coarsely demolded. Once completely cooled, the clay matrix which has hardened considerably in contact with fire is first removed using a small pointed hammer. Then comes a long work of cleaning all the small clay impurities which adhere in the many details of the sculpture using a wire brush and a punch. At this stage, many sculptures are eliminated because of their faults: air pockets which prevented the flow of metal to the ends of the sculpture, cracks that appeared on drying, imperfections during the production in wax causing a break (on fragile parts such as fingers, headdress, jewelry, etc.) ...
The last step is polishing, which is now done mechanically.
The sculpture is now ready to be sold either on a local market or to a wholesaler who will distribute it throughout India.