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Friday, February 27, 2015

Silver Bubbles? Look Again, The Worlds Finest Casting Grain

It may look like silver bubbles, but it's actually #sterling silver casting grain. Casting grain, or #silver shot is used by jewellers, silversmiths and goldsmiths to create one of a kind cast jewelry items. Sterling casting grain is little balls or BB's about 2-5 millimetres in diameter made of 92.5% silver, 5% #copper and 2.5% #zinc. The copper gives it strength and durability while the zinc adds an antioxidant element. 

Casting grain is easy to use, easy to melt, and because it's pre-alloyed, the finished product is of outstanding quality.

Silversmiths pour a measured amount of grain into their furnace, and once melted pour into a mold containing one or several shaped voids, known as casting. Hence, casting grain.
Sterling silver casting grain at KMG Gold Recycling

Posted by Mike Gupton at 11:50 AM 0 Comments

Wednesday, June 29, 2011

Casting Grain

Casting grain is done by jewelers when creating unique gold grains. Typically, high quality pre-casting grain comes in different karats and colors. The colors are created depending on tastes and color preference. Typically, the strength and color of the grain being cast will largely depend on the chemical composition of the metal being used, whether it is silver, gold, copper etc. Generally, the ratios of silver and copper in an alloy have a bearing on the overall color of the alloy. The ratios of the same will also determine the strength and hardness of the alloy. When casting grain, the chemical composition of the alloys mainly determines the overall characteristics of the outcomes.

As such, alloy chemistries are very important in determining color. But in cases where the chemistries create a challenge, jewelers will typically compromise. When using high zinc content, jewelers run the risk of creating bigger, unusual shrink voids. Other than this, grain such as red karat gold can be difficult to cast, as it forms copper oxide slag. In addition, red karat gold is highly susceptible to porosity.

Certain silver and copper variations may also force jewelers to compromise. Silver and copper content in certain variations can create very hard castings that are hard to work with. To mitigate this, jewelers prefer casting grain with tried and tested compositions of the various metals.

Generally though, workable casting grains feature a fine detail that is demonstrated by proper flow and fill characteristics. In addition, workable grain also has a clean as-cast surface and no impurities at all, such as oxides. Other than these, jewelers will also give preference to workable grain that has very minimal shrink characteristics, but with excellent physical attributes such as ductility and malleability. Workable casting grain has to be nearly as fine as-cast grain size and should be able to harden with age.

When casting grains, a jeweler chooses the best color for a cast after deciding on the Karatage of the gold being cast. However, the color of the gold being cast will solely depend on the relative amounts of silver, gold, copper, zinc and nickel being used. For instance, when casting colored karat gold, whether red, green or yellow; silver, zinc and copper will mostly be used.

White karat gold uses alloys of gold, copper, nickel and zinc. On the other hand, palladium white gold is also used sometimes and contains alloys of gold, palladium and silver. In addition to color requirements, the mechanical characteristics of an alloy are also important. Such mechanical properties include malleability and ductility, and depend on what the alloy is being used for. Therefore, casting grain depends on a number of factors that jewelers must consider when looking for quality outcomes.

Posted by Mike Gupton at 9:52 AM 0 Comments