Indian Jewelry Bangles In UsaSandcast jewelry making was introduced by using sandstone or tufa stone. Tufa stone is created from crushed volcanic ash which is relatively soft and easier to work with than sandstone when making the carvings. However Sandstone will hold up much better, but the Tufa stone is is the choice among Silversmith because the soft stone is easier to carve.
There are many processes involved in Sandcast jewelry making before the jewelry piece is finished. The artisan starts by cutting a stone into two pieces and grinding both halves until they are smooth on one side. The tufa stone is sometimes drenched in water to keep the dust to a minimum while carving. Next, vents are carved into the stone outward towards the edges of the stone so that the extremely heated air from the molten silver will have an escape from being trapped in the mold, thus damaging the jewelry design. The next step involves heating the mold with a torch forming carbon on the inside of the halves preventing the silver from sticking to the mold when the halves are separated. Finally the mold is ready to start the silver casting.
The halves of the tufa stone are placed together with the pour channels aligned. The, artisans use a number of methods, such as wrapping with wire, plywood board and clamps, or rubber straps tightly around the halves to keep them secure while pouring the molten silver.
The silver is then heated in a crucible with a torch until it is at a high temperature of 1850 degrees. Traditionally, temperature was judged by the color of the molten silver. That is still the most common method used by many artisans today, but now use crucibles that where the heat is digitally controlled. This increases the chance for a successful pour. The temperature of the outside air must also be taken into consideration. If it is very cold, the silver can become too cool before it runs through the mold. When the silver is judged to be hot enough, it is poured into the mold through the carved channel.
The molten silver is then poured down through the channel and into the carved mold. Thus the piece is said to have been gravity cast. The tufa stone mold is allowed to cool and the silver piece is removed.
A tufa mold may allow several pours if the design is small and relatively simple. With larger, more complex designs, one or two pours is usually all that can be made from a tufa mold before the stone breaks or the design is ruined by the heat of the silver. The artisan at this point may determine that the jewelry piece obtained from the Tufa mold will be in demand and start the process of making molds of the more stronger Sandstone.
After the jewelry piece has cooled, polishing the finished jewelry is done in two phases. First the silver piece is polished wax and then washed to remove the excess wax. Next the jewelry piece is dry polished with buckskin or a dry cloth wheel, and finally, stones, if any, are set. Tufa and sandcasting processes are very labor intensive, taking many hours to make the mold, then carving the design into the two stones, depending on the detail. The finished piece have cost the artisan many hours which must be taken into account in setting the price of jewelry created by the sancast jewelry making method.
