The authoritative public forum
  for Metal Finishing 1989-2025
  

  -----

Residue from copper that has been patina'ed

I am building a cupola and intending to place a weathervane on the top. The roof of the cupola is a pre-finished metal with a dark color. We purchased a weathervane that came with a patina finish, which we assume was simply the manufacturer accelerating the process. When I opened the weathervane, I noticed that there was some green powder on my hands, and I am concerned that this powder will wash down and streak the roof. Here is my question - is this powder a normal result of accelerating the patina, and can I simply wash the weathervane to remove the excess powder before I install it...?

Tom Dowling
Architect - Hartford, Connecticut
2007

---

Yes, to all. You can wash the powder off to gain a little time, but it will stain the roof anyway. And whether the patina is natural or accelerated, it is a fairly soluble marginally adherent copper salt. Look at old cupolas or green statues in public parks -- they all stain their surroundings. Learn to love it :-)

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

---

2007

Ted -

Thank you for the prompt response. Given your recognition and expertise in the industry, I now have the "ammunition" when my wife wants me to climb 35 feet in the air and wash stains off the darn roof - I'll just direct her to the park in the middle of town and tell her that we are making history in our own back yard. You have saved me a lot of grief...!

Regards,

Tom Dowling

Tom Dowling
Architect - Hartford, Connecticut

---

And thank you for the excuse to post pictures of a couple of my favorite buildings --

 

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007