Ask Samantha #18: Metallic Copper Turned Green

Help! My copper turned green!

Q. I took your Metallics abstract acrylics class in Okotoks. I really enjoyed the class and I hope to be able to make many more paintings the way you taught us. Today I tried varnishing the two paintings I made on Saturday. I did two layers of varnish on one painting as per your online instructions. However, the copper leaf I used on the painting turned green. Did I use too much varnish? Will the varnish clear and will the copper return to its original color? What can I do about it?

A. Unfortunately, there is no way to get the copper back. Waiting for the varnish to dry will not reverse this. No, you did not use too much varnish. You used the wrong kind.

When it comes to working with metallic powders, leaf and foils, I always advise my students to work with spray varnish instead of a liquid varnish. The spray varnish keeps the powder from spreading all over the canvas and will help the colour stay true to itself.

The thing to keep in mind about my painting process is that it is highly experimental. We are using products in ways in which they were not originally intended. When we do this, we open ourselves up to the possibility that things might go astray.

The only other thing that I can think of, is that perhaps the copper you used was suspended in a green colour. Another way of saying this is that the formula for making the copper colour includes the colour green. Make sense? When you rolled on the varnish, it caused a chemical reaction of some sort. 

At this point, if you want the copper back in your painting you will have to add some more. Once you've added the copper back in, finish things off with a spray vanish.