Aging metals

[Slowhand Bob]

Guys what techniques do you use for aging your leathers assembly or decorative metal parts?  Talking copper, brass, steel, silver, nickel, etc for the conchoes, rivets, spots and whatever else you use in your leather work that might need that older look.   

[Nolan Sackett]

these are for copper based materials such as brass, copper, bronze, Sterling, and nickel.

http://www.sciencecompany.com/patinas/patinaformulas.htm

for steel/iron: cold blue and chlorine bleach