Mold having a breathable release sheet across the top

Claim 1

Mold for casting foamed urethane plastics material for foam plastics articles having at least one generally flat surface and being fully finished on all sides ccomprising, in combinaTion, a mold box having a generally flat upper surface provided with a recess extending downwardly through said surface to define a generally open and unobstructed aperture in said flat upper surface and a cavity contoured to define the article to be molded and a generally flat lid extending across said aperture for containing the plastics material within said cavity during foaming and rise thereof together with a breathable release sheet extending across said aperture and across said cavity beneath said lid closing said cavity to fully define the article to be molded, said breathable release sheet consisting of a layered structure comprising, in turn, a self-supporting paper support later having sufficient strength and rigidity to be selfsupporting across said aperture without sagging into said cavity or wrinkling during rise of such plastics material and exhibiting sufficient gas porosity to enable complete venting of such cavity through said release sheet outwardly between said mold box and said lid during foaming of urethane plastics material deposited therein in an uncreamed state while precluding exudation of such material therethrough and a release material layer coated to at least the surface thereof toward said mold box to prevent adherence to such foam, so that the gas porosity of said sheet is substantially unencumbered by said release coating, to enable the production of a finished flat surface thereagainst accurately reproducing the texture of said release sheet without flaws or voids caused by trapped air, wrinkles, and the like.