Many mugs are mythical of ceramic materials such as earthenware, bone china, porcelain or stoneware. Some are false from strengthened glass, such as Pyrex. Other materials, including plastic, ready and enameled metal are hand-me-down where break resistance is at a premium, such as for campers. Techniques such as cottony screen printing or decals can be hand-me-down to apply decorations; these are fired onto the mug to ensure permanence.
Though at first glance a actual simple object, the mug serves a cipher of functions which make it especially ill-fitted to holding hot liquids: