When a molten metal is cast in a mold that is a poor conductor, the dominant resistance to heat flow is within the mold wall. Consider conditions for which a liquid metal is solidifying in a thick-waned mold of thermal conductivity k... and thermal diffusivity an. The density and latent heat of fusion of the metal are designated as p and hsf, respectively, and in both its molten and solid states the thermal conductivity of the metal is very much larger than that of the mold.