A Marver is a tool used in glassblowing. It generally is made of a polished steel surface attached to a metal or wooden table. A warm piece of glass is rolled on the marver, for two reasons: controlling temperature and adjusting shape. Because of the high specific heat capacity of the steel, it can absorb heat from the glass, particularly the outer skin. Because the glass comes in direct contact with the steel, it must be kept very clean. It is usually rubbed with steel wool and then wiped with rubbing alcohol to keep it from rusting.