Copper magnet wire

Self-supporting coils are wound with wire coated with at least two layers, the outermost being a thermoplastic that bonds the turns together when heated.

Other types of insulation such as fiberglass yarn with varnish, aramid paper, kraft paper, mica, and polyester film are also widely used across the world for various applications like transformers and reactors. In the audio sector, a wire of silver construction, and various other insulators, such as cotton (sometimes permeated with some kind of coagulating agent/thickener, such as beeswax) and polytetrafluoroethylene (Teflon) can be found. Older insulation materials included cotton, paper, or silk, but these are only useful for low-temperature applications.