The enamelled copper wires are exclusively made of Cu-ETP.

They are always annealed which makes them quite malleable and they must have a possible minimum elongation of 25%.

It is always the bare copper diameter (nominal diameter) which is used as the reference for the wire.

According to the temperatures of use imposed on the wires, there are different qualities of varnishes.

• polyurethan base coated varnish covering the wires of the range of temperatures 155°C  (IEC 60317-21) ou 180°C (IEC 60317-55).
• polyesterimide base coated varnish covering the wires of  the 210°C thermic classs ( IEC 60317- 13)
• simple polyimid base coated varnish covering the wires 220°C class  or aromatic polyimide for the 240°C class (IEC 60317-46)

The indexes of temperature (also named thermic class) of these enamelled wires mean that they can, in theory, work 20000 hours at the mentioned temperature.

• Polyurethans are used for static coiling (transformer, choke coil, ...). Theorically, they can be soldered without being first scraped., the insulating layer vanishing in the heat (about 360°C). That is why they are called solderable. They can have different colours (green, blue, black, purple), but most of the time, they are light yellow or red. This doesn't have an influence on the insulating power.
• Polyesterimid varnishes  are used for rotating machines (motors, alternators,dynamos). They are brown-coloured and are generally named unsolderable because they must be scraped before use.  
• Polyimide base coated wires are generally  used for  the very effective rotating machines very often working at high temperatures and in enclosed atmospheres (trains, planes, nuclear,...) and must be scraped before use as well.