Patent ID: 8376024

Claim:
A process for manufacturing a metal casting free from pinholes and other blowout gas defects comprising, providing a mold, said mold having an active surface, heating and maintaining said mold to a temperature between 250° F.-600° F., prior to introducing a molten metal at an elevated temperature into said mold, a coating suspension mix is applied onto said active surface of said mold, said coating suspension mix having dispersed therein a quantity of refractory glass that constitutes from 10.0% to 55.0% by weight of the coating suspension mix, said refractory glass being inert at said elevated temperature of said molten metal to be cast and having a brittle state at said elevated temperature of said molten metal, said suspension mix having a carrier liquid for suspending said quantity of refractory glass, wherein said carrier liquid and said refractory glass combined constitute at least 95.0% by weight of the suspension mix, wherein said refractory glass is nonporous to said carrier liquid and said carrier liquid is vaporizable at a temperature from 250° F. to 600° F., drying said carrier liquid on said heated mold for at least five minutes in duration whereby said carrier liquid is vaporized and no further water vaporizes or are other gases generated, after said five minutes a thermal insulating coating remains on said mold active surface, said thermal insulating coating is inert and nonreactive to said molten metal.