The brass casting that is done in Goa is called as ‘sand casting’ where the casting process happens by the use of sand molds, so the term sand casting will refer to the casting done through sand casting process. Most of the complex metal castings are done in this method. It is comparatively cheap and sufficiently refractory hence this method mostly is used in brass casting small-scale industries. To carry out the process of brass casting – Preparation of molds and needed tools and materials has to be kept handy. First the model to casted is done and then molds are designed after which metals are melted and poured into the molds to get the castings.
Preparation of molds:
The molds are formed of desired even shape of a desired part. To create a mold – two or three kinds of soil (jungle soil) are mixed together along with a suitable bonding agent (usually clay). The wooden plank with design pattern is placed on ground, chalk powder is sprinkled on top of the design so that the sand mixture doesn’t hold onto it and the mold frame is placed on the plank, it is tightly filled with sand mixture and covered with another wooden plank on top. The wooden plank with the design pattern is below so it is turned upside down. The wooden plank is removed leaving the pattern in sand. Chalk powder is sprinkled on it and another box frame is placed tightly filling it with sand later. The box is covered with plain wooden plank after filling with sand. There are two box frames along with the pattern still inside. The first frame is slowly lifted and kept aside. The pattern is taken out and the two box frames are put back together after making a pathway for the molten metal to pass and is kept aside. By the same way number of molds are made for the bulk production.
Once the mold is ready the furnace is set up and the metals are melted in a crucible in a furnace. It takes about twenty minutes for small amount of metal to melt. Once it is melt the bigger grains and dust are removed. The crucible is held with tongs and carried to the molds. The molds are filled with molten metal. Castings are taken out after cooling the molds for few minutes. The castings are separated from sand and placed in water. The castings are buffed and polished to give a finished look.