The black surface of black tungsten wire is mainly because graphite emulsion is sprayed during the drawing process. As a lubricant, graphite emulsion can effectively reduce the friction coefficient between the tungsten wire and the drawing die, reduce the risk of tungsten wire breakage during the drawing process, and extend the service life of the drawing die. After the graphite emulsion adheres to the surface of the tungsten wire, a thin black coating will be formed, which is also the source of the appearance characteristics of black tungsten wire. The graphite layer can be removed by alkaline washing.
