Glass for electrical insulators can be classified into quartz glass, soda lime glass, lead glass, borosilicate glass, etc. according to their main components.

1. British glass: British glass is made by heating and melting silica sand and crystal powder at about 1800 ° C. It is almost completely non alkali, has high resistivity, low dielectric loss and excellent insulation performance. In addition, the coefficient of thermal expansion is small, because of good chemical stability, it can be used for high-frequency insulation.

2. Soda lime glass: Soda lime glass has low price, low softening temperature, and easy forming and processing, but it is not suitable for electrical insulation due to its many alkali components. However, in recent years, the dielectric properties have been improved by adding BaO. In some countries where excellent insulators cannot be obtained, Langdon has made insulator materials for power distribution and transmission.

3. Lead glass: Lead glass is a kind of glass containing PbO, which has low softening temperature, easy processing and good insulation performance, so it can be used as the glass for vacuum tubes.

4. Borosilicate glass: borosilicate glass has less alkali components harmful to electrical performance, and it is easy to melt and spit out. It has good mechanical strength, stable cold and heat resistance, and excellent insulation performance. For example, "Pyfex" (USA), "Terex" (Japan) and other well-known commodities are used for insulating materials, antenna insulators, communication insulators and other high-frequency equipment of communication equipment.

5. Alkali free glass: The glass fiber used for the insulation coating of power lines, etc., is glass with high alkali content, which has poor chemical stability and insulation performance, so it is necessary to use alkali free glass as the raw material.

The main components of glass are acid oxides such as SiO2, B2O3 and AL2O3 and basic oxides such as Na2O and K20. The raw materials include silica sand, feldspar, borax, calcium carbonate, and many other natural materials and industrial drugs. A small amount of auxiliary materials shall be added as clarifying agent and reducing agent. Blending these raw materials, adding a considerable amount of cullet, heating at a high temperature above 1300 ° C, and melting for a long time until the bubble disappears. Then, the automatic forming machine is made into the required shape and then annealed. For products that require high strength characteristics, such as suspension insulators for power transmission lines, keep the molded products at a temperature slightly lower than the softening deformation temperature, quickly take them out of the furnace, and use nozzles to blow cold air for quenching and tempering. This treatment can fix the compressive stress of about 800kgf/cm2 on the surface of the glass, which plays the role of resisting external forces and essentially toughens the glass.