Patina

A little fakery played on time by chemistry.  A piece of steel tubing in the middle of the patina process.  The first spritz of chemicals reacts with the steel to produce a tarnished copper look.  That's followed by another to turn everything darker to an oiled bronze color.  This is after the second spritz, when the pieces have dried.  Next, they are wire brushed to remove the white metallic salts.