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Joukowsky Institute for Archaeology & the Ancient World
Brown University
Box 1837 / 60 George Street
Providence, RI 02912
Telephone: (401) 863-3188
Fax: (401) 863-9423
[email protected]
Posted at Mar 09/2011 07:21PM:
BMB: From Wikipedia In archaeological terminology, 'grog' is crushed fired pottery of any type that is added as a temper to unfired clay. It can be produced by firing selected fire clays to high temperature before grinding and screening to specific particle sizes. The particle size distribution is generally coarser in size than the other raw materials used to prepare clay bodies. It tends to be porous and have low density. Grog is used in pottery and sculpture to add a gritty, rustic texture called "tooth"; it also reduces shrinkage and aids even drying. This prevents defects such as cracking, crow feet patterning, and lamination. The coarse particles open the green clay body to allow gases to escape. It also adds structural strength to hand-built and thrown pottery during shaping although it can diminish fired strength.
EZZ: it is a ceramic raw material, with high percentage of Al and Si (silica and alumina)