This coarse-grained, 20-mesh grog is sold by the pound or by the full 50-lb. bag. This is a calcined mullite grog, used throughout the ceramic industry and available in a variety of mesh sizes. This grog can be added to throwing and sculpture clay bodies to increase working strength and reduce shrinkage, although some people may find the texture a bit coarse for wheel-thrown bodies. Adding grog to your clay also aids in drying thick pieces.