The maximum capacity that a fine-grained, porous, granular material can absorb a liquid into the pore structure of the individual grains and still remain free-flowing. The point where the liquid impregnated granules adhere to the sides of a container (i.e. become “wetted”) represents a rough measure of internal liquid holding capacity of the material (i.e., the point beyond where granules begin adhering together and lose free-flowing properties).