Silica stone powder applied to the bottom of vessels to prevent fusing during firing. However, in regions where good quality silica stone powder is difficult to obtain, ashes are sometimes used. This is called mesna ash. This is also a silicate.
Sand for making mezuna sand is made from sand with large particles that settle quickly during hydrofiltration of potter’s clay, so in regions where hydrofiltration is not used, mezuna sand is not often seen.