Protecting Copper Patina

Fabrication | Jewelry | | | |

Hi there. I was rooting through my little treasure bin and I found a little bottle of something blue that had purchased from a jewelry supply store during a going-out-of-business sale. It was cheap, sounded promising, so I bought it. Just now trying it. It appears to be some kind of verdigris (not that I really know what that means), as when rubbed on copper, a beautiful bluish green oxidation of sorts will appear, then dry very chalky and fragile. It is easily wiped off with just a finger. Too bad. I love the color. Is there a recommended way to either seal this (without a thick, unseemly coating on the work) or create a more durable, similar finish?

The bottle says something about "for mokume" - it's a name "Johnson's" or something. I'll dig it out and relate the name tomorrow if it makes a difference to anyone.


Rich Waugh's picture

David, It sounds like some

David,

It sounds like some sort of copper sulfate or cupric nitrate solution. Try diluting it half and half with water and then spraying the copper with it - warm the copper up to around 150-200F first. After spraying it, put a box or plastic can or something over it so the stuff stays moist longer. Then let it sit overnight and spray it again the next day. The longer it sits in a moist atmosphere, the better the patina will hold up. Generally speaking, the more dilute you can get the patina to work, the more durable it will end up being. Time is your friend on this - be patient. :-)

Once you get the color you want, coating it can be tricky. Many patina colors are to some degree the result of refracted light and coatings tend to kill that. Copper sulfate and copper nitrate patinas aren't so bad about this, fortunately. Still, a coating that "drowns" the patina will deepen and dull it, killing the subtle hues. The best coating I've found is Permalac - pricey but effective and doesn't seem to alter the look much at all if applied correctly - several thin coats, no flooding.

Hope this helps. Give us a report on your results, okay? We're all learning here at your expense. (grin)

Rich


Daverham's picture

Double post? Sorry... Not at

Double post? Sorry...

Not at my expense at all! I'm having a lot of fun. I would tend toward "naked" metal as opposed to any kind of coating, so I'm going to try the slow build up approach first. We'll get to the coatings after that. You can expect some photos.

Thanks for the tip about diluting. I should have known. I have been tarnishing silver and copper for years with this little bottle of liquid liver of sulfur and only recently found out that diluting it (a lot) can generate all kind of subtle blue and brown tones. I had no idea! This has added some nice subtle colors to my work.

Here is a silver/Chrysoprase ring that I did on Sunday. I used diluted liver of sulfer for the tarnish. At one point it was a rich brown color, I might go back to that - or just keep it in mind for the future. Ans in case someone asks, I did cut that cab too.

Chrysoprase and Silver Ring

Anyhoo... pics of green patina copper coming up as soon as I have time to play with it!


Rich Waugh's picture

Yep, you forgot to log in.

Yep, you forgot to log in. No prob, I deleted the duplicate.

Rich


johndach's picture

patina on copper

Pretty much agree with what Rich has stated. If you can get a "tooth" on the metal surface and the design will allow for this, the patina will have something to grab on to verses a polished surface. Waxing can help retain the patina, but the copper salts are pretty fragile so a clear coat is often called for. I use Incralac, I get it in spray cans from Custom Arisol in Iowa. I usually buy it by the case as there is a haz mat fee and it is about the same for the case or one can. The cans end up costing me about $13.00 each delivered. You could try a spray lacquer from the paint store too, they just are not formulated for use on copper and outside as are Incralac and Permalac. Also might suggest you try some of Ron Youngs copper patinas if interested. You can call them and they are very helpful if you get into a "what the heck!!!" situation...

John Dach
john@MLCE.net
web site: http://www.MLCE.net and ctmandalas.com