micanite

Micanite is a flexible insulating material derived from mica that is formed into sheets or papers by binding mica flakes with resins such as shellac or phenolic resin. In historical electrical engineering literature it is commonly called micanite or mica paper and was used as high-temperature electrical insulation.

Composition and manufacture: mica flakes are layered and bonded with a binder, then compressed into thin sheets, tapes, or rigid boards. The material can be impregnated with resin to improve moisture resistance. Micanite exhibits high dielectric strength and stability at elevated temperatures and is resistant to many oils and solvents. Its performance can be affected by moisture, with dry micanite being more brittle and resin impregnation helping moisture resilience.

Applications: it was used to insulate windings in transformers, motors, and generators, especially where heat resistance was required. It also found use in vacuum tubes and other high-temperature electrical components, as well as in older equipment and in certain niche modern devices that demand durable high-temperature insulation.

Today: micanite has largely been supplanted by modern mica-based laminates and other high-temperature insulants, but mica papers and related products remain available for specialized applications where temperature stability and chemical inertness are critical. Availability is through specialized electrical insulation suppliers.