For a good many years the accepted method of cementing ceramic joints was with a mixture of fire clay grog and a plastic clay binder. This did not prove too satisfactory for several reasons. Usually when enough plastic clay was added to give good workability the vitrification was lowered to such an extent that either excessive shrinkage or excessive bloating occurred, depending upon the extent to which the vitrification point was exceeded...In order to obtain a cement with high strength throughout a long firing range the manufacturers have turned to the addition of various organic binders and inorganic fluxes. Most widely used of these foreign ingredients is sodium silicate...Reported as also capable of producing a ceramic cement is a substance call Calgon, chemically, sodium hexametaphosphate...It was decided to further investigate the possibilities of sodium hexametaphosphate as a ceramic binder and to investigate as far as possible the feasibility of the new metaphosphates as ceramic binders --Introduction, page 1-3
