Aluminum Mill Finish The mill finish profile is an aluminum alloy extruded semi-finished product without any coating treatment on the surface, which material before being processed into a finished product. The mill extrusion will naturally oxidize for a long time, and it will be black and not bright. At present, aluminum profiles are commonly known as 6061 and 6063. The difference between 6063 and 6061 is: 6063 is softer than 6061 6061 is used in various industrial structures requiring high strength, weldability and high corrosion resistance, such as pipes, rods, profiles and plates for trucks, tower buildings, precision machining, etc 6063 is used in building profiles, irrigation pipes and extruded materials for vehicles, stands, furniture, fences, etc.