There is a company called Modern Options that sells a patina solution at crafts/arts stores. They have a website modernoptions.com and they do sell at big stores like Michael's and The Home Depot (California locations, at least.) Anyhow, they have various colors and they do sell the verdigris which I have used. I am an artist and I do copper drawings on huge sheets of copper foil, and have been all around on this subject, finally having some wisdom to share! If you don't want to use that approach (the modern options) you can make a solution of salt dissolved in vinegar. brush or spray the solution on CLEAN copper--clean with a lemon dipped in salt, and then immediately wash with soap and water and do not touch with bare hands. The oils from your hands will make the patina not stick. By the next day there should be a good patina on your surface. You can spray with water to stop the patina process, but make it a gentle spraying. This will also show you what color the roof will be if you decide to spray with lacquer. The lacquer will change/darken the appearance of the patina.
All the best!!!

Urine will react with copper. Collect some and brush it on a sample of the copper to judge the results. Cost will be low!

Miracle Grow plant food is supposed to work well. Cheap, but not as cheap as urine.
;-)

******UPDATE******

Thanks Rosemarino, I tried as you suggested with the vinegar and salt solution. Lo and behold, green patinated copper roof on my dovecote.... Great tip, I'm delighted with the result, thanks again,

Kev

Rosemarino --
What ratios on the vinegar/salt solution please? I want to age some copper plumbing pipe.
Thanks!
Gayle

I just had copper snow guards put on my roof and they are so BRIGHT I can't stand it. I saw the instructions on greening the copper, but I just want to darken it... I want it to be the color it would be if I let it age for 4-6month. Will the same solutions work?

THANK YOU!!!

Looking for advice on how to age new copper gutters and copper gutter helmet to a silveresh gray patina finish. Trying to keep the blue green effect out. The old copper gutters were patinad years ago to this finish. Any advice?

Any selenium based solution such as gun bluing will work to age copper, brass, and bronze.

Selenium followed by mineral oil CAN help get it more gray. It will not turn silver.

LIVER OF SULFUR will turn copper a darker color. Depending on the concentration it can be anywhere from a light gray blue tone to a dark black.

You can get it online at jewelry supply websites. As a jewelry, I use this all the time on copper and sterling silver. It is fairly permanent. It can be sanded off. It can be painted or sprayed on. I would get a scrap piece to test different methods of application.

I have copper gutters and roof from six years ago that is now dull copper tone. It should have turned green by now, so it must have been coated. How can I get rid of the coating and get it to green?

Ketchup also works

"Ketchup also works"

Acetic acid (vinegar) and salt.

I have not used any of these solutions yet, but I plan to try the salt and vinegar mixture Im going to be putting it on a table surface so Im wondering about a good way to seal the table top once its done. Someone said on here to use marine grade polyurethane but Im concerned about that being too strong if I decide to change the finish in the future. Any thoughts?

The "Copper and Brass Finish Treatments" link posted above now seems to be Copper and Brass Finish Treatments.

I also ran across this online: Patina Formulas for Brass, Bronze and Copper

Urine, animal or human will turn copper green. Weird but true. When the parliament building in Victoria, Vancouver was built, they put on a copper dome. The government wanted it to be green before they dedicated the new building. They put the word out that they needed cow or human urine. The people of Victoria were happy to donate to the effort. When the building was dedicated, the dome was a beautiful green.