Antiquing brass and copper.

[crazyman]

I've tried lime juice, salt, vinegar, battery acid, and ammonia. Guess which chemical won out? Ammonia. I dipped the pieces into Ammonia, then stood them on end to drain on a spray can lid above the Ammonia and gently sealed the lid on the ice cream tub to let the vapors work.

I'm building a fuel rail for a three deuce Ratrod for my buddy, and Ammonia did the trick to make it petina'ed..

This ad brought to you by the Ammonia producers association, JK...

[crazyman]

Hmm.. Sitting here reading my post, I wonder how ammonia would make a ported head appear unported...

[crazyman]

[XLR8R]

Antiquing copper & it's alloys - as in Verde Patina (i.e. Statue of Liberty)?

Cupric nitrate and heat - apply with a brush when surface temp is above 215*F, repeat as needed to achieve desired hue - too many coats (~>2-3 dozen) can cause seperation of sacrificial coating on flexible substrates... many years of experience with a coloring torch in my younger days.
Nostalgia is dampened by memories of Antique Brown application - the Sulferated Potash required was especially stinky as the water steamed away!