Selected carbon black types act as a lubricant in metal casting processes. For example, in foundry molds they help to release to final product and prevent sticking.
In the casting process, the surface of the melted metal typically oxidizes in the high temperatures. To prevent this, mold fluxes are used to cover the surface to prevent oxidation processes. Carbon black, used as an additive in the mold flux, helps regulate temperature and allows the casting process to continue without oxidation. In continuous copper casting, some special carbon black grades can be used without any additives to cover and protect the liquid copper. The temperature of this process is significantly lower.