Brass- This is mainly used to cast different objects and artifacts.
Burnt clay- This is taken from previously broken moulds or burnt and broken by the craftsmen. If there are no tools available for breaking, the craftsman lays the mould on the road in front of their houses to be broken by passing vehicles.
Cow dung- This is mixed with mud to form a mixture used as the base as well as outer coating when making the mould.
Water- This is mixed in desired quantities to the mud- cow dung mixture to form a smooth paste. It is also used to test the effectiveness of the custom made drainage structure created in the mould.
Vegetable oil- This is used as a lubricant to grease the interior of the extruder as well as wooden board when rolling out wax sheets.
Beeswax- This is made into strips and coiled to create various patterns in the mould which shapes the final design. The material retains its malleability even it has cooled down after being heated.
Saras- This is a kind of resin gum that is mixed with beeswax to create wax threads and strips.
Coal- This is used as fuel in the kiln.
Wax, Ash, Backed clay mold
Tools & Technology
Furnace - This is used to bake the mould and also to melt brass.
Coal-pick - This is used to add coal in the furnace fire.
Iron file - This is used to polish and finish the final casted metal product.
Pincers or tongs - Used to handle the mold when pouring in the molten metal.
Lachhna - iron strips, used for different purposes like heating the wax, sticking with hot wax, etc.
Kati - small iron chisel used to cut wax strips and designs.
Hatha - This is a wooden tool, used to make wax strips and thick wax sticks.
Patha - This is a wooden board used for working the wax materials.
Pichkari - Multi-holed syringe like tool used to create wax threads. 'Sikkey' or coins are small metal coins with holes of different diameters inside the Pichkari, which help in drawing out threads of required thicknesses.
Kachni - wooden stick used for sticking and shaping small wax rings.
Kavelu - Terracotta tile piece used for smoothing and shaping the core.
Hammer - This is used to break open mold.
Axe - This is used to break open the baked mold to reveal the final product.
In designs which are either large or have a hollow space within, the core is made with sand. In the last stages of the production, sand is removed leaving a hollow core behind thereby, greatly reducing the amount of brass required to build the complete design.
Usually the core is made with a mixture of fresh and burnt clay. In this process the black burnt clay is first sieved in a moderately large vessel that has been covered with an old, gauzy cotton cloth. The dust is poured over the cloth and rubbed with hands to help it pass through. Burnt clay is used here because it doesn't shrink after drying and is easily removed from the finished product due to its weak binding strength. At this stage a small quantity of cow dung is added to the burnt clay and mixed together creating the core mixture.
The stability of the core at high temperatures is determined by the proportion and composition of these materials. The core mixture is shaped by hand to a desired form and left to dry naturally. If done properly cracks should not develop after drying. At this stage the core is rough and a little larger than the desired form. It is buffed using a terracotta tile to achieve a final shape removing any excess materials. The terracotta pieces are dipped in marl to add strength and achieve a smooth finish. The designs are left to dry in the sun for a few hours.
To prepare the wax an appropriate amount of beeswax and resin are mixed to together in a calculated ratio. During the winter months less amount of resin is used as it hardens the mixture quickly.
The mixture is filtered through a fresh piece of cotton cloth and the process involves two persons, as one holds the cloth the other pours the mixture. The wax needs to be stirred continuously through the cloth for an easy and quick flow. The filtered pure wax is collected in a container filled with cold water which is kept underneath the cloth. The collected wax is stored for hardening. After half an hour the hardened wax is taken out of water, broken into 4-5 pieces and kept in sun light for 4-5 hours. This softens the wax and is kneaded with hands for approximately half hour making it malleable enough to be drawn into wires.
The wax is worked by two methods, rolling into flat sheets to be stored away or by drawing into long wires using an extruder. Flat sheets are also made with 'Hata' on the wooden platform. Before making sheets small quantity of oil is applied on the platform and the wax lump is placed on it. Sheets are made by beating the wax lump with the hata.
In the latter, wax threads of different diameters are created by changing the extruder plate. Sheets are used to create flat surfaces while the threads are used to make coiled lines. A coin shaped part is fitted in the nozzle of the extruder or 'Pichkari' and changed according to the diameter required. Some amount of vegetable oil is applied inside the nozzle and a small lump of wax is inserted in it. Wax threads are drawn by pressing the wax lump with the piston.
When the wax melts away, it generates a gap between the core and the mould. The core pins are provided to prevent the core from moving inside the mould when the wax melts away and the brass has not yet been poured into the cavity. These pins are iron nails pushed into the core which fixes themselves to the moulds. The use of core pins result in a uniform wall thickness of brass and prevents irregularities such as holes.
After a pattern is made using wax, a wax runner is fixed to it form a point. This assembly is dipped into soil slurry. The slurry is able to seep into the minutest details of the design due to its intricate consistency.This improves the surface quality of the product. After the slurry dries, this is again covered with a coarse mixture of cow dung, soil and hay to make the final mould.
Brass pieces are usually scraps obtained easily in the local markets. The calculation of how much brass needs to be used in the product is determined as 6 times the amount of wax used. A hemispherical clay pot holds the scrap with some salt added to it as flux. The pot is covered with a flat clay disc with holes. The mould is stuck on top of this using clay at the joint.
The furnace is a pit dug into the ground having an intermediate grid. The chamber below the grid has an air passage which opens at the ground level after running a little distance away from the furnace. Cow dung cakes, used as fuel, are placed above the grid. The opening for air is attached to a blower. A layer of coal is added on top of this. The firing of furnace takes place mostly in the day, to avoid the heat of the daytime.
When the brass has melted the mould is picked up using tongs and shaken to check if the metal has come to the molten state. The wax melts away, leaving a cavity for the metal to be filled with. The mould is then inverted to enable the molten metal to flow into the mould from the clay pot.
Once the metal settles in, the mould is cooled for a while in air and then immersed in water. It is then cracked open and filed to reveal the exquisite product. When the mould is broken, the metal changes its colour due to oxidation so it becomes important to polish it properly to regain the original colour and shine of the metal.