Black Bar: Used to buff contaminants out prior to finishing. Will remove rust, stains, scale, and other contaminants. An extremely fast cutting material. Also called emery cake.
Brown Bar: Used for buffing aluminum, brass, copper, wood, plastics, hard rubber, and painted surfaces. Also called Tripoli rouge.
Red Bar: For buffing precious metals like gold, silver, platinum, sterling, and other high end metals. Can also be sued to further enhance materials that have already been buffed with other compounds. The finest grade.
White Bar: Used for buffing stainless steel, carbon steel, nickel, aluminum, and chromium to a high luster shine.