Glassware is mostly soda-lime silicate glass, which is colorless and transparent, and the iron content in the glass is generally lower than 0.02%. Colored glass can be made by adding colorant to glass raw materials; Add sunscreen to obtain opaque glass (see glass manufacturing). Potassium lead silicate glass, also known as lead crystal glass, is often used to make high-grade artistic utensils such as goblets, perfume bottles and fruit pots. This kind of glass contains PbO, which has high refractive index and large dispersion. When grinding the blade surface, it is particularly bright, with high specific gravity, and it makes a crisp sound when knocking. All lead crystal glass contains more than 30% PBO, lead crystal glass contains 24-30% PBO, low lead crystal glass contains less than 18% PBO, and barium crystal glass contains BaO. Cookware such as coffee pot adopts heat-resistant borosilicate glass, which has low thermal expansion coefficient and strong temperature resistance. Glass-ceramics have good heat resistance, rapid temperature change resistance and high mechanical strength, and are suitable for making hotel cookers and frequently washed utensils.