Silver is a precious metal used in applications ranging from photo processing and coins to eating utensils and dishes. One of the more ubiquitous uses of silver is in jewelry. As a relatively malleable material, silver products can be made in a number of ways including casting. Casting is process in which, typically, molten materials are poured into prepared molds. There are a number of casting techniques in which silver can be used.
Sand casting is, according to the Swiss Gemological Laboratory, the oldest method of casting. For simplicity, a description of small scale sand casting provides a general process overview. Sand casting is done with two mold frames, generally made of steel or aluminum, that are open on the front and back. The model (object to be copied) is placed into one of the frames and sand is packed around it very tightly. The other half of the frame is filled completely with sand. A groove or casting gate is made on both sides of the frame that extends from the top of the molds to top of the model depression, reports jewelry website Ganoskin. The sand is dried and then molten silver can be poured into the casting gate and allowed to cool. Sand casting is probably the easiest casting process to perform in a non-professional setting.
Lost Wax Casting
One of the more popular casting process in use is called lost wax casting or investment casting. In lost wax casting a model is created from wax and affixed to the base to hold it in place. The model is placed in a flask and covered in a type of plaster, after which the flask is put into a vacuum chamber to remove air, reports The Rams Horn studio. Once the plaster sets with the model in place, it is fired or kilned which causes the wax to melt or evaporate and leave the plaster with empty space inside that replicates the model. The melted silver, or alternate metal, can then be poured into the mold and allowed to cool.
Die casting is generally used in large scale operations, due to the high equipment and set up cost involved. In the die casting process, the molten silver is mechanical forced into a specialized mold called a die. Dies are permanent molds, frequently made from steel, that may be held shut mechanically or with manual latches. Once the metal cools, the mold is opened to release the cooled product.
Plaster and Ceramic Casting
Two alternative casting methods are plaster and ceramic casting. According to Swiss Gemological Laboratory, plaster and ceramic casting follow the same essential process as sand casting. The difference is that plaster or ceramic materials are substituted for the sand.