this invention relates to a method of compressing ceramic refractory bodies which can be designated as &# 34 ; hot forging &# 34 ;, as distinguished from &# 34 ; hot pressing &# 34 ;, although both processes involve the compressing of formed porous bodies of ceramic refractory material to decrease their porosity and increase their strength . the hot forging process utilizes a breakaway mold having cooled die members . the porous ceramic body has been prepared for the compression by being heated to a pyroplastic temperature . it is rapidly compressed within the cold mold , a temperature gradient of the order of 1000 ° c . being maintained from the cooled inner die surfaces to a depth of not over 5 milliliters into the body from the die - contacted outer surfaces . while a thin porous skin is formed around the body , its thickness is limited to not over the depth of the temperature gradient . the body is released from the mold by separating the die members in directions perpendicular to the contacted sides of the body so as to limit abrasion of the outer surfaces of the body .