A heavy duty sulfurized-chlorinated base oil that helps cut clean, sharp threads on steel and brass pipe. It is formulated to reduce friction during the machining process. By reducing this friction heat generation is minimized. The results are cleaner, sharper threads, better fitting joints and longer tool life. Black Swan's DARK CUTTING OIL is formulated to work on high speed machines. For hand threading applications use Black Swan LIGHT CUTTING OIL. Black Swan's DARK CUTTING OIL is an anti-mist lubricant. Weather conditions will not affect the oil. The quality of the oil is guaranteed to be uniform at all times. The oil is also ideal for stripping, broaching , or milling applications.