Bill, if you've been following the forum here, this topic has been brought up many times. There is NO clear coat that will last more than a year or two without periodic maintenance. Polyurethane is NOT UV resistant. Please post some photos, if you can.
What are your "realistic" expectations for the copper top?

 

Why not let it age out to a beautiful dark color. You won't be able to keep it copper colored for long. It will only oxidize to a certain point to where the oxygen is cut off to the metal, then stop.

 

Use copper so you have no upkeep to worry about.

 

Copper is kept shiny copper color is chrome plated with out the nickel layer.

 

I appreciate the feedback.
I’m a retired chemical engr & spent 40+ yrs in the chemical & plastics industry. The best UV coatings are not available in retail. Red Spot Paint & Varnish did sell their products through paint stores but discontinued that years ago. I painted a metal sign for my church with their paint (red color) about 15 yrs ago & it still looks good. It sees full afternoon sun. (The original red coating on the sign faded badly within 2 yrs.)
Since I’m spending the time to refurbish the cupola (some wood replacement, repainting the wood, copper top old paint removal), I want to have the bright copper look as long as possible. ( We may sell the house within 2 yrs but nothing is certain.)
I could let it weather naturally to that green oxide patina but have decided otherwise.
i plan to use a coating that doesn't quickly yellow. As long as the coating doesn't crack or flake off quickly (2 yrs+?), there will be an oxygen barrier in place. If I can get my rear-end moving, i can re-coat it in 1.5 yrs. It’s a small garage with easy to access the roof.
I would provide a pic now but i had already disassembled some of the wood housing before I decided to do this post. Once it’s ready to be re-installed & after it’s installed, I’ll post pics.
Thanks for the opinions. I was hoping there was a great product out there that I didn’t know about.

 

I appreciate the feedback.
I’m a retired chemical engr & spent 40+ yrs in the chemical & plastics industry. The best UV coatings are not available in retail. Red Spot Paint & Varnish did sell their products through paint stores but discontinued that years ago. I painted a metal sign for my church with their paint (red color) about 15 yrs ago & it still looks good. It sees full afternoon sun. (The original red coating on the sign faded badly within 2 yrs.)
Since I’m spending the time to refurbish the cupola (some wood replacement, repainting the wood, copper top old paint removal), I want to have the bright copper look as long as possible. ( We may sell the house within 2 yrs but nothing is certain.)
I could let it weather naturally to that green oxide patina but have decided otherwise.
i plan to use a coating that doesn't quickly yellow. As long as the coating doesn't crack or flake off quickly (2 yrs+?), there will be an oxygen barrier in place. If I can get my rear-end moving, i can re-coat it in 1.5 yrs. It’s a small garage with easy to access the roof.
I would provide a pic now but i had already disassembled some of the wood housing before I decided to do this post. Once it’s ready to be re-installed & after it’s installed, I’ll post pics.
Thanks for the opinions. I was hoping there was a great product out there that I didn’t know about.

Automotive clear coat they put over paint??

 

Polishing the cupola top is out. The prior homeowner had it painted because some of the original lacquer coating had worn off. It’s not possible to get a uniform look. I’m going to finish the wood repair and give it 2-3 weeks to see if a uniform patina forms. I’m doubtful it will. I’ll paint it if it doesn’t.

 

The pic of corn got in by mistake. Tried to edit the post but got a message that I don’t have permission to delete it.

 

I had the same issue this afternoon about deleting a photo in a draft post that wasn't even posted yet. It should clear up soon.
Edit: I just did the weekly reboot of my laptop and internet modem, and the photo went away. So it may be within your operating system.
Would you consider artificially accelerating the patina with chemical methods ??

 

I had the same issue this afternoon about deleting a photo in a draft post that wasn't even posted yet. It should clear up soon.
Edit: I just did the weekly reboot of my laptop and internet modem, and the photo went away. So it may be within your operating system.
Would you consider artificially accelerating the patina with chemical methods ??

Just remembered that need to log in through the web rather the email link.

What would accelerate the oxidation? I’ve wiped it down with acetone. The spots without lacquer oxidized in seconds.

Car clear coat? I'm lost.

they have become big in the auto market in last 15 yrs. They have more than automotive coatings. Maybe I don’t understand your question/ point.

 

Just remembered that need to log in through the web rather the email link.

What would accelerate the oxidation? I’ve wiped it down with acetone. The spots without lacquer oxidized in seconds.

they have become big in the auto market in last 15 yrs. They have more than automotive coatings. Maybe I don’t understand your question/ point.

Why not use car clear coat on your copper, would be the question? Every body shop has it.

 

My post is irrelevant to your question, but I remembered in high school we were taught to remove a patina from copper to use the Ketchup bottle from the pantry.

The mixture of Aspic (tomato juice), and acetic acid (vinegar) will shine copper up really well with minimal scrubbing.

As suggested, I would get a quality stripper (no not gypsy Rose), and strip all the old finish, then shine it, and have an auto body shop clear coat it.

ED

 

My post is irrelevant to your question, but I remembered in high school we were taught to remove a patina from copper to use the Ketchup bottle from the pantry.

The mixture of Aspic (tomato juice), and acetic acid (vinegar) will shine copper up really well with minimal scrubbing.

As suggested, I would get a quality stripper (no not gypsy Rose), and strip all the old finish, then shine it, and have an auto body shop clear coat it.

ED

And also lemon juice and salt - works great on copper-bottom pots and pans.

 

I think the OP's cupola has patches of NON copper and will never "polish" up. Paint may be his only alternative.

 

Rut-Rhoooo - Having more time to examine this more closely, please correct me if I'm wrong, BUT, it appears the cupalo "could be" copper plated TIN and not true, solid copper sheeting.
It would be in your best interest to dig at it deeply on the inside to see if it is solid copper. Also, put a magnet to it to see if it sticks. I'm not feeling good about this. UNLESS, the "greenish" colored object is just paint that hasn't been removed yet.

 

That blob appears to be BONDO applied to fill in a rusted-out spot.

Therefore, this is just a scab job.

Unless O P wants to rebuild it with fresh new $$ copper, they are doomed to repaint and move on.

ED

 

Don't over-think it. Yes, the poly will give you a year or 2 of the fresh copper looks, but then it will degrade, and the patina will form. However, it may wear away at different intervals leaving you with a couple of years of blotchy patina. I'd just polish it up nice and enjoy a few weeks / months of the fresh copper. Then let it go green. It's the way copper is supposed to look.

 

See post #19

 

So here’s something no one has mentioned yet. Bare copper metal, whether it has patina or not, will actually improve the health of your roof. When rain water washes over the copper it picks up microscopic particles of the copper (or its compounds) and deposits them on your roof. Mold and mildew do not like the copper and hence they do not stay on your roof. I intentionally had a copper ridge cap put on my roof about a year and a half ago for the very purpose of protecting the roof itself. Now the copper has turned to about the color of an old penny.

Next time you’re driving around neighborhoods look for homes with any kind of copper fixture on their roof. Also look for galvanized (zinc plated) fixtures. You will almost always notice what appears to be a stain down stream of the metal fixture. It’s actually an indication of where the roof has been healthier because of the presence of such a metal. Do a little research and you will find what I’m saying to be true.

 

An interesting page from Red Spot labeled 'UV Products'. ...... Sounds interesting, but I saw NO products listed on this 'UV Products' page. I did see 'pictures', but no links to anything giving ANY details.

UV • RED SPOT

Red Spot has earned a reputation for creating cutting-edge UV coating solutions for a wide variety of applications.

www.redspot.com

 

My post is irrelevant to your question, but I remembered in high school we were taught to remove a patina from copper to use the Ketchup bottle from the pantry.

The mixture of Aspic (tomato juice), and acetic acid (vinegar) will shine copper up really well with minimal scrubbing.

As suggested, I would get a quality stripper (no not gypsy Rose), and strip all the old finish, then shine it, and have an auto body shop clear coat it.

ED

I use Bartender's Friend to clean the bottom of my copper-clad pots and pans. I've learned it works best if applied with hot water. Saves a lot of rubbing compared to using it with cold water. Hot water with a slight paste of BF on a wet sponge will do a beautiful job.

You can pick up Bartender's Friend at most grocery stores in the cleaning aisle near the Comet powder cleaner, etc.

we use this all the time. It’s a great product. Biggest use is on the stainless kitchen sink.

 

I added copper sheeting to a cuppalo several years ago to outdoor kitchen and cleaned it thoroughly. I sprayed it with automotive clear coat and it has remained copper colored ever since.

 

Here’s the cupola re-installed. I decided to let the copper roof stay as it is. My wife wanted it that way.

 

Absolutely NOTHING wrong with that. Wife has good taste.

 

wow - looks awesome from where I sit !!!

 

You are a wise man.

When SWMBO speaks listen.

I like it.

ED