Enamel drinking glasses are also a good choice. Enamel is a composite material in which inorganic glass materials are melted and solidified on metal at thousands of degrees. Enamel coating on the metal surface can prevent rust, so that the metal will not form an oxide layer on the surface when heated and can resist the erosion of various liquids. Enamel products do not contain harmful substances such as lead, are easy to carry and clean, and are widely used as eating utensils and washing utensils in daily life. The enamel cup has a disadvantage. The enamel cup is afraid of bumping, and the surface is prone to damage. Studies have shown that damaged enamel cups are prone to precipitation of harmful substances when serving drinks, and should be eliminated decisively.