Aging new copper?

[voipio]

Just tried ferric chloride on some copper tape and, as you say, the metal stayed bright, but my recollection from years ago was that partially etched and rinsed copper would have a dullness to it, and would tend to darken fairly quickly. There were probably other chemical vapours about, which helped the process, including sulphuric acid aerosol from lead acid batteries being (over)charged. I do remember fingerprints would reveal themselves on clean copper over the course of a few days.

The mystery is solved. I have, in the past, tried a recipe using ferric chloride with hydrochloric acid added to it, to try to speed up the etching process. That mixture definitely "ages" the exposed copper, as I've just tested it. I don't have the exact proportions to hand, but guessing it was about 10ml of conc HCl added to a litre of ferric chloride, which rings a bell. For the test, I used 10 drops of ferric chloride solution and 1 drop of conc HCl.

 

[Smallfry]

Tourmaline. Sold by Liberon. Used in the antiques trade to fool you into getting something old ! I have some if you want to borrow it. Dip and done !

Easiest way though, it just wait 50 years if you have the patience