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Discussion Starter #1 (Edited)
I'm not sure if I'm in the correct area of the forums here. But, I got an old decorative copper bell. (You tap it with a stick to make the sound.) It has been out in the elements for a number of years and started degrading. I used vinegar and salt to try to polish it. However the reaction caused the paint to come off. I'm not sure how to go about painting it.

(Picture on top is it dry. Picture on bottom is it wet.)
 

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Baby Fire:

Copper rusts, but the oxide layer it forms is very different than the oxide layer that iron or steel forms. Copper oxide is a brown colour and is fairly impermeable to the oxygen molecules in the air. So, as that oxide layer grows in thickness, it better and better protects the underlying metal from further oxidation. This is why plumbers that sand the copper oxide layer off of copper pipe prior to soldering it find that the oxide layer on 50 year old copper pipe isn't all that much thicker than the copper oxide layer on 5 year old copper pipe.

If the vinegar and salt solution was able to remove the brown copper oxide layer and leave the underlying metal bright and shiny, then I'd use the same treatment to remove the copper oxide from the bells. If it didn't, then I'd probably try a product called Brassco (IIRC) that's mean to sprucing up old brass fixtures.

Once you get the copper nice and shiny, make sure it's dry and paint your bells inside and out with Tung Oil. Tung oil is a drying oil very much like linseed oil. It will take days for each coat to dry, just like linseed oil, but, once you coat your copper with Tung Oil, it will act as a physical barrier between the copper metal and the oxygen in the air, thereby keeping the copper bells looking shiny as they were when you applied that Tung oil.

You should be able to find Tung Oil at most paint & hardware stores and home centers. I would use a sponge brush to apply several THIN coats of Tung oil. Several thin coats is all you need.
 

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You did say that you want to paint it correct?

To paint metal it needs to be CLEAN and then primed, and then painted.

Are you wanting to restore the original design, or create a new one?

You could clear coat what is there now and have close to what it looks like wet now,

Brasso will just shine the copper to natural appearance as well as TARN-X, or other commercial copper pot cleaners. And it will oxidize once more to the copper patina you see on unprotected copper pipe.


I am still confused as to what you want this to be .


ED
 

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You could clear coat what is there now and have close to what it looks like wet now.
ED
Ed is correct. The reason why giving those things a clear coat will give them a permanent wet look is because coating the metal with a transparent liquid or a transparent solid or a liquid that dries to form a transparent solid will cause MORE light to reflect at the SMOOTH interface between the air and the clear coat and less of the light to be reflected at the clear coat/copper interface, which is exactly what getting the metal wet does.

As it stands now, all of the light that's reflected is reflected from the air/copper interface, and that copper is rough and it scatters light. Your eye sees scattered light as the colour "white", which is why clouds and snow banks are white. By putting a clear coat over the copper, much more light will be reflected at the SMOOTH air/clear coat interface, which doesn't scatter light and so you won't see that "pale" look the bells have now when they're dry.

This is the result of something called "Fresnel's Law" which says that the fraction of light reflected at an inteface is the difference between the refractive indices across the interface divided by the sum of the refractive indices across the interface, all squared.

http://en.wikipedia.org/wiki/Fresnel_equations
 

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Discussion Starter #5 (Edited)
I want to restore it to the original design. It was originally black and orange and I really want it to be as close to what it originally was as possible.

Edit: Or a reddish orange. It's a little hard to tell.
 

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That design is going to be very difficult to re-create.

Take many many pictures, strip off the old faded paint, then primer it well, and patiently start with the base color, and patiently add the design .

Did I say patiently, it will take time, but you can do it.


ED
 

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I wouldn't start trying to repaint it.

I would clean up the brass and copper as best you can, and then give it a few coats of Tung Oil to prevent them from tarnishing or oxidizing again.
 

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Polyurethane (as long as it's a true alkyd based polyurethane, and not some water based polyurethane) would probably also work to provide a physical barrier between the copper metal and the oxygen in the air.

I suggested Tung Oil only because I know it's still available for sale, it yellows less than linseed oil and forms a harder and more durable coating than linseed oil. And I know that any drying oil, alkyd or alkyd based polyurethane would provide an impermeable barrier to the oxygen in the air.

Also, Tung Oil is also often called China wood oil, and so if the OP want's to restore these bells, China wood oil would probably be the most appropriate clear coat to use on them.

http://en.wikipedia.org/wiki/Tung_oil
 

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Polyurethane (as long as it's a true alkyd based polyurethane, and not some water based polyurethane) would probably also work to provide a physical barrier between the copper metal and the oxygen in the air.

I suggested Tung Oil only because I know it's still available for sale, it yellows less than linseed oil and forms a harder and more durable coating than linseed oil. And I know that any drying oil, alkyd or alkyd based polyurethane would provide an impermeable barrier to the oxygen in the air.

Also, Tung Oil is also often called China wood oil, and so if the OP want's to restore these bells, China wood oil would probably be the most appropriate clear coat to use on them.

http://en.wikipedia.org/wiki/Tung_oil
Tung oil wood be a much more traditional finish, as well as being much easier to maintain.
 

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Discussion Starter #11
It's me again. I went to the hardware store, and it looks like Tung oil is used for wood. The employee also seemed confused as to why anyone would suggest that oil for copper.

So, I'm not sure about the advice you were giving me. :/
 

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I went to the hardware store, and it looks like Tung oil is used for wood.
Tung oil is normally used over bare wood.

The employee also seemed confused as to why anyone would suggest that oil for copper.[/quote}

Because Tung Oil is a drying oil, which means that the film it forms as it dries is highly impermeable to the oxygen in the air. So, by painting your copper bells with Tung Oil, you put an impermeable coating over your bells which protects them from tarnishing in future.

So, I'm not sure about the advice you were giving me.
No problem. Happens all the time. The 16 year olds working in hardware stores presume I don't know anything compared to them because I'm not working stocking shelves in a hardware store.
 

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Tung oil is normally used over bare wood.

The employee also seemed confused as to why anyone would suggest that oil for copper.[/quote}

Because Tung Oil is a drying oil, which means that the film it forms as it dries is highly impermeable to the oxygen in the air. So, by painting your copper bells with Tung Oil, you put an impermeable coating over your bells which protects them from tarnishing in future.



No problem. Happens all the time. The 16 year olds working in hardware stores presume I don't know anything compared to them because I'm not working stocking shelves in a hardware store.
And tung oil is what a 1000 year old Chinese guy would probably use. Between stocking shelves anyway.
 
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