Rotational casting mold

Claim 1

In a mold for rotational casting of plastic wherein said mold is formed in two mating sections with one section having a raised tongue and the other section having a groove disposed to received said tongue, and wherein said mold sections each have plural complementary face means disposed to sealingly engage each other, and means to secure said sections together with said complementary face means of each section in sealing engagement and with said tongue in said groove, the improvement comprising vent means to permit escape of gas from between the complementary faces of said sections during heating, so that said gas is vented to the exterior of the mold preferentially to escape of said gas to the interior of the mold, said vent means including, channel means formed in one of said complementary surrounding said tongue outside said tongue, first aperture means extending from said channel means to the outside of said mold, and second aperture means connecting said groove with the outside of said mold, said plural complementary face means being essentially free of passage from the groove to the mold cavity.