Sleevings are manufactured by coating braided heat treated Fibreglass sleevings with thermosetting polyurethane Varnish qualified for class 'F' (155 °C) operation. It is resistant to acids and most organic solvents and compatible with a broad range of wire enamels, polyester, polyamide, polyimide and polyvinyl formal. By virtue of cross linking, the polyurethane film will not flow upto application of heat. It is available in colours as well as the natural appearance of cured resin.