Abstract: A mold comprising a cavity for defining the shape of a casting and a mold body for forming said cavity, comprising: a mold body formed of an ordinary temperature setting resin or thermosetting resin and casting sand, said mold body having a surface layer portion on the surfaces thereof including depressions, said depressions in the surface layer portion being filled up with at least one porous powdered material selected from the group consisting of hydrous magnesium silicate clay mineral, activated carbon and activated alumina, thereby providing the mold body with smooth surfaces whereby said mold generates less amount of material such as gums which cause defective castings during casting since molten metal is restrained from intruding into the walls of said mold.

Abstract: A mold surface treatment process comprises: providing a fluidized bed of a treating powder; holding the mold in the fluidized bed to fill up the depressions of the mold surfaces with the treating powder by employing a surface treating member for pushing the treating powder into the depressions; and taking the mold out of the fluidized bed. The mold surface treatment allows to make molten metal less likely penetrate into the walls of mold, and to manufacture a mold which generates less amount of gum causing defects during casting.