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Grog
Sorry, matey, this kind of grog is not
something the English army used to drink. Instead, it's a
refractory material that's often used to make more durable casting
molds.
Grog usually refers to one of two different
products. One is pre-fired clay that has been ground and
screened to a specific particle size. This product is usually
available at ceramic supply stores, and is also known as chamotte or
firesand.
The term grog is also used to refer to
ground up silica bricks. (This type of grog is often called
"silica grog".) You can make these yourself by grinding
bricks, but it's easier and safer to purchase it pre-ground and
sifted by particle size. Silica grog also tends to be more
refractory than clay grog (it can withstand a higher temperature
without deteriorating), and is probably the best choice for molds
that will be fired at or above fusing temperatures for a longer
period of time.
Grog can usually be added to any casting
mold formula to increase durability.
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Copyright 2006 Brad Walker.
All rights reserved.
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