Copper as Oil Painting Support

[keron]

Would anyone like to offer some information on how to prepare a copper surface for oil painting? I've been hunting around on the net, which is usually a good way to start, but have come up pretty much empty-handed.
On a recent trip to Atlanta I found some copper sheets intended for printmaking. At @ $12 a sheet I snatched the four sheets in stock.
I know there are some painters out there ussing copper as a support for easel painting so I am hoping this forum will be an excellent place to refocus my research. Thanks in advance.

[ 16. October 2007, 18:39: Message edited by: Admin ]

[Kenneth Freed]

Copper is a wonderful traditional surface to paint on. So many beautiful portrait minatures were done on copper and they are in a remarkable state of preservation. You can clean the surface with an acetone to do a little degreasing. Then it is helpful to abrade the surface a little for adhesion with steel wool and/or sand paper. I would use an oil ground with a pigment that you could sand without creating toxic dust such as titanium. Put on several coats, sanding lightly between coats when dry. You can get a very smooth white surface to work on this way. You can of course use lead white ground but I am not comfortable with sanding lead white. You can also file the edges a little before priming and round the corners a little to avoid sharp points that can make life unpleasant.

[ 12. December 2009, 12:36: Message edited by: Kenneth Freed ]

[keron]

What about painting directly onto the copper plate sans primer coat? There seem to be painters who do this wanting the copper to shine through and bbe part of the final effect - Benjamin Shamback as an example.
Then again, I've read in certain places that the copper can turn the colours greenish. This doesn't seem to have been a problem for the Flemish old masters.

[Kenneth Freed]

It would of course be possible to paint directly on a copper plate in oils without a ground. Our administrator would be a good source for information about pigment reactions when painting oil directly on copper without a ground. It may well be that there are only a few pigments that would be reactive. I have never seen any old master paintings on copper that didn't appear to have a ground. That doesn't mean that they don't exist, I just haven't seen them. It is possible, on the other hand, that the copper was painted without a ground solidly without any voids of copper showing and one assumes that they were grounded. One potential problem with leaving some of the copper voids showing is the oxidation, it may start out shiny but will look like an old penny eventually. If the changing nature of the oxidation color doesn't bother you, then that wouldn't be a problem. There may be a possiblility of coating the bare copper spots with a translucent laquer to slow down the oxidation. Or if you want a patina, you could use some chemical spotting to encourage growth of the lovely green patina.

[George O'Hanlon]

Copper is a wonderful substrate upon which to paint. It is also less liable to cause cracking in the paint layers from deformation usually experienced with stretched canvas and wood panels. Studies have shown that it promotes drying of oil paint and strong film formation.

Although one could paint directly on the copper, you will have a much easier time of painting if you first apply an oil ground. Prepare the surface of the copper by lightly sanding it with fine sandpaper. Clean the surface thoroughly: degrease it with an aliphatic (mineral spirits) or aromatic solvent (xylene) and remove all copper particles. Apply the oil ground, preferably one containing lead white, to the copper surface. Allow to dry and scrape smooth, if necessary. If you must sand a lead oil ground, be sure to wear a dust mask and avoid making too much dust, wiping up all dust and wet mopping the floor once you are done.

For sources of copper sheeting and plates (over 10 gauge), there are a number of places online where they can be purchased. Here are several online stores:
Storm Copper Components Co.

Copper Basics

Online Metals

[ 16. October 2007, 12:46: Message edited by: Admin ]

[keron]

Thanks you both for the concise and informative responses. You've left me with options to consider and ways to act on them.
Mr. Freed, I'd havee to agree with - I don't think I've ever seen ay old master works on copper where the entire surface wasn't covered by paint. Naturally one would assume there was a ground involved.
It's with current painters that I seem to find indication of painting onto copper straightaway. Shamback is the clearest example. Jack R Smith, the Taos painter seems like he might paint directly...it's really only the sense of a glow of the metal coming through the paint layer. I am guessing because Smith does paint edge to edge.
Then there is Richard Murdoc. He seems to use a lead ground at least some of the time.
Do you think that a varnish coat would protect the metal from oxidation?

[Kenneth Freed]

Keron, it is my belief that you could slow up some oxidation but probably not completely eliminate it. You could do a little experimentation with some small copper pieces. You could polish some and then try some coating materials that might seal the shine. I might try some clear laquer sometimes used for furniture finish. I am not sure that any specific resin/varnish used for oil painting would be as effective or any more effective than clear laquer for sealing out oxidation. Please let us know what you find out with your experimentation, we would love to hear from you.

[George O'Hanlon]

A urethane varnish coat will provide a good moisture barrier and protect the copper surface from oxidation. However, I would not use this varnish in the painting side of the copper sheet, but to seal the back side.

[Alfredo]

Hi, George. I found some copper plates sitting around my studio that were covered in etching ground and unfinished. I have cleaned the goruned off with paint thinner and am about to start abrading the surface with sandpaper. I have no lead ground but I do have a lot of your lead white paint. Is there a way I can prepare an oil ground with it?

Thanks,
Alfredo

[George O'Hanlon]

You can mix the following with lead white: an equal amount by weight of chalk, and then enough linseed oil (50:50 mixture of pale linseed oil and heavy viscosity bodied oil) to obtain a stiff paste. Grind this mixture with a muller on a marble or glass slab until smooth. Add more of the oil (above) and mineral spirits or turpentine to the mixture to obtain a mixed paint that can be brushed onto the surface of the copper plate. The primer should level and show little or no brushmarks within a few minutes of application, if you have mixed sufficient oil and thinner with the oil color and chalk mixture.

For a more opaque primer, you can substitute about one-third of the chalk with titanium white.

Be sure to degrease the plate with acetone or another degreasing solvent before applying the ground. Allow the solvent to completely evaporate before working on it.

Apply at least two thin coats of the lead ground, allowing each coat to dry before applying the next.