Printex L 6 Imported furnace black Degussa Extenders / Fillers >> Carbon black Pigments >> Carbon Black SEALANT Printex L 6 Imported Furnace Black (Conductive) Conductivity. Used as a pigment in caulks for interior and exterior applications and in expansion joints. Conductive imported furnace black. Used as a pigment in caulks for interior and exterior applications and in expansion joints.