Grog
Crushed Brick, Body Agregate
Miscellaneous
- Family: Aggregate
- Region: None
- Mined At: Unspecified
- Raw Mineral: No
- Generic: Yes
Notes
Grog is a granular material made by grinding brick or other fired ceramic although it can also be made by crushing certain natural minerals. It is marketed in designations that refer to the size range of the particles. 20-40 mesh grog means that all material under 40 and over 20 has been graded out to provide a material whose particle size range is tightly controlled.
Grog is used mainly as a clay body addition to control drying and fired shrinkage and to open the body to allow quicker venting of water vapour during drying and gases of decomposition during firing. It does on a large scale what 200 mesh silica does on a microscopic scale. A sculpture body typically has 20-30% grog.
Since grog is normally prefired, its does not undergo a firing shrinkage. This means that the more that is put into a recipe, the less the clay shrinks. However, more grog also means less plasticity and wet strength. It is possible to get maximum benefit from a grog addition if its complement is added in specific size ranges and amounts (testing is required to achieve maxiumum density).
It is possible to achieve a pressing or non-plastic forming body with almost zero shrinkage by mixing a body with 90% or more grog. The heavy refractories industry commonly uses a 50% 4-16 mesh, 10% 20-36 mesh, 40% 40-60 mesh mix of grog and a deflocculated slip to bind them together for drying. This principle can be extended to almost any grogged clay body.
Suppliers
- Generic
Authors
- Tony Hansen (Owner)
XML
<?xml version="1.0" encoding="UTF-8"?>
<material name="Grog" descrip="Crushed Brick, Body Agregate" generic="1" rawmineral="0" searchkey="" loi="0.00">
<families>
<family name="Aggregate"/>
</families>
<suppliers>
<supplier name="Generic" country="" url="" label=""/>
</suppliers>
<notes>
<note>Grog is a granular material made by grinding brick or other fired ceramic although it can also be made by crushing certain natural minerals. It is marketed in designations that refer to the size range of the particles. 20-40 mesh grog means that all material under 40 and over 20 has been graded out to provide a material whose particle size range is tightly controlled.
Grog is used mainly as a clay body addition to control drying and fired shrinkage and to open the body to allow quicker venting of water vapour during drying and gases of decomposition during firing. It does on a large scale what 200 mesh silica does on a microscopic scale. A sculpture body typically has 20-30% grog.
Since grog is normally prefired, its does not undergo a firing shrinkage. This means that the more that is put into a recipe, the less the clay shrinks. However, more grog also means less plasticity and wet strength. It is possible to get maximum benefit from a grog addition if its complement is added in specific size ranges and amounts (testing is required to achieve maxiumum density).
It is possible to achieve a pressing or non-plastic forming body with almost zero shrinkage by mixing a body with 90% or more grog. The heavy refractories industry commonly uses a 50% 4-16 mesh, 10% 20-36 mesh, 40% 40-60 mesh mix of grog and a deflocculated slip to bind them together for drying. This principle can be extended to almost any grogged clay body.</note>
</notes>
</material>
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