The development of a cellulose acetate lacquer treatment for textile insulated wire has made available an improved type of wire for telephone central office use. The desired improvement in electrical characteristics is obtained when the textile fibers are laid down and covered by the cellulose acetate film. The accompanying graphs show the comparative electrical characteristics at various humidities, of wires insulated with commercial and purified cotton and silk servings, before and after treatment with cellulose acetate lacquer.