New stronger formula BCR for your toughest cleaning jobs. Works effectively on gold, platinum, silver, steel, stainless steel, zinc, magnesium, brass, copper and aluminum. Concentrated: use between 3% and 20% by volume depending on extent of compound buildup. Exceptional rinsability eliminates hand wiping, streaking and discoloration. Also available in 4-gallon, 19-gallon and 51-gallon containers.