Liver of Sulfur SOL600.04

An oxidizing agent for brass, copper and silver that results in patinas from a light gold to a dark gray or black. Chunks, keep in a cool dry place. 4 oz.

WARNING: Contains Sulfuric Potash! Harmful if inhaled, swallowed or absorbed through skin. May cause burns or skin irritation, use in a well ventilated location.

If you don't want to use a chemical you can get some good results with torching your metal or heating in an oven.