The residue tests indicated a very high percentage of non clay material entering the ceramic recipe, with as much as 40% free quartz in clays from specific areas of the deposits. It was then possible to locate the sections of the main clay deposit that held clays of a better quality.

These clays were again tested for residues, with the clay on the left hand side containing notably less debris. Simple sedimentation tests were also carried out in glass cylinders containing the liquid clays. The faster the clay in suspension falls will give an indication of its low plasticity. Again the clay in the l.h.s. cylinder can be seen to be in suspension and indicates a better quality material.