Electrical Properties

Volume Resistivity - Is the resistance in ohms between opposite faces of a centimeter cube of the glass tested. Its value is stated in ohms-centimeters, and it is tested per ASTM D 257. This is important when glass is used as an electrical insulator.

Dielectric Constant - of a glass is the ratio of the energy stored in a condenser with the glass as the dielectric, compared with the energy stored by the same condenser with air as the dielectric. It is a measure of the ability of a glass to store electrical energy and varies with the frequency of the voltage applied to the condenser. The dielectric strength is measured per ASTM D 150. This is important when the glass is used as a substrate for electrical or electronic devices.

Surface Resistivity - the ratio of the potential gradient parallel to the current along its surface, to the current per unit width of the surface. Surface resistivity is measured according to ASTM D 257. This is usually specified as ohms per square centimeter (O/cm2) or just ohms per square. This method is used to measure the conductivity of coated glasses.