These glazes need a certain thickness to float materials to the top surface of the glaze. This creates interest where the glaze pools in texture or drips. (If the glaze is applied too thinly, the glaze will not be able to float. The end result will be flat and probably an incorrect color.) The tiles show the float developing as the glaze is applied more heavily. Float makes these glazes perfect for layering. (Blue Rutile can be very fluid if applied too heavily.)
Tableware producers must test all finished ware to establish dinnerware status, due to possible variations in firing temperature and contamination.