Patent ID: 8133933

Claim:
A molding composition comprising: a refractory particulate material suitable for making a mold for casting metallic articles, wherein the refractory particulate material is at least partly coating with a resin mixture comprising: a phenolic novolac resin; a phenolic resole resin having a viscosity of from about 100 centipoise to about 5,000 centipoise at a temperature of 25° C.; hexamine; and less than 1,000 ppm by weight of calcium based on the combined dry solids weight of the phenolic novolac resin and the phenolic resole resin wherein the phenolic novolac resin has a dry solids weight of from about 60% to about 99%, based on the combined dry solids weight of the phenolic novolac resin and the phenolic resole resin, and wherein the phenolic resole resin contains from about 55% to about 75% solids.