The usual properties are (1) strength - ability to maintain shape in the face of the flowing
metal, (2) permeability - ability of the mold to allow hot air and gases to escape from the cavity, (3)
thermal stability - ability to resist cracking and buckling when in contact with the molten metal, (4)
collapsibility - ability of the mold to give way during shrinkage of the solidified casting, and (5)
reusability - can the sand be reused to make other molds?