These washers won't melt, stick, or become brittle, even when exposed to temperatures as high as 1050° F. They make excellent insulators and are often used to secure electrical connections in transformers. Mica can chip and flake due to wear, however, so these washers are not recommended for high-vibration applications.

Cover screw heads or nuts to block electrical current and prevent short circuits. These washers isolate fasteners from sensitive surface-mounted components, such as capacitators and transistors on printed circuit boards. They also extend the life of your assembly by preventing galvanic corrosion, which is when two different metals rust more quickly due to contact with each other.