The Copper Challenge — Autumn 2019

The Objective

The goal of my copper challenge is to see how painting directly on a 10″ x 8″ copper panel compares to painting the same subject on a piece of linen glued to an aluminum panel.  Aluminum is my normal support for oil painting.

The Hypothesis

Light reflected back from the shiny copper will make its way to the viewer through layers of transparent oil paint. This effect gives the painting a warm glow. Since my subject is a brass kettle, the result should appear more authentic than if I tried to render a brass kettle the normal way.  This is the result I anticipate from my copper challenge.

Why Copper?

Copper has a long history and solid reputation among traditional painters.

Some cool reasons to love copper:

  • Historically, oil paintings on copper have held up well over the centuries.
  • Copper can be one of the most problem-free supports if maintained in a suitable environment (free of air pollution and high humidity)
  • Oil paint bonds extremely well to copper, and is unlikely to ever crack due to the copper support (There are many other reasons that may cause oil paint to deteriorate but a copper support is not one of them.)
  • The migration of copper ions into oil paint can strengthen the adhesion of the paint to the panel and reduce the oil paint’s drying time.
  • Copper does not respond to changes in relative humidity (RH), which is the cause of the most stress and strain on paint films and one of the leading causes of cracking and paint loss.
  • The coefficient thermal expansion of copper (i.e., how it expands and contracts with changes in temperature) is similar to that of oil paint, so copper does not cause much stress for oil paint films.

The Setup

In my home studio, I focused a small LED lamp on my on black still life stand where I placed:

  • dusty old brass kettle that used to sit on a mantle in my parents’ family room
  • a wooden cutting board
  • a lemon

For the control panel, I added a tea bag. For the copper panel, I added the end of a lemon instead (see the images below).  Just for some variety.

I placed my easel next to the still life stand so I could employ the sight-size method of painting from life.

My control panel is an 10″ x 8″ Artefex “AllinPanel” from Natural Pigments.  This product consists of fine linen primed with lead white oil that is adhered with BEVA 371 to a two-sided aluminum composite panel. This is my preferred painting support.

The copper panel is also an 10″ x 8″ Artefex panel with a natural (smooth) finish.  (To be precise, it is a a copper composite panel, consisting of one copper veneer and an aluminum veneer laminated to both sides of a black polyethylene core).  I also have a textured / abraded panel that I will use in a similar setup for the next copper painting.  Both are 4 mm thick.

I did not prepare the surface of the panel other then cleaning it with a microfibre cloth (a soft lint-free cloth) moistened with isopropyl or denatured alcohol and allowing it to dry. And I avoided touching the surface with my fingers; oil from fingerprints can interfere later with the adhesion to the oil paint.

In the gallery below you will see: my still life setup for the Control painting, the setup for the Copper painting, and the panels in their original packaging…

Please click on an image to see a full version of it.

Lemon Tree — The Control Painting

I created the Control panel in a very conventional way:

  1.  On regular paper taped to a drawing board, I drew the setup.
  2. I transferred the drawing to the Control Panel — linen on ACM panel.
  3.  With burnt sienna, I created an underpainting.
  4.  On my palette, I laid out the colours needed for the kettle, cutting board, lemon and tea bag:
    • a variety of red, orange and yellow ochres
    • raw and burnt sienna
    • naples yellow, cadmium yellow
    • pre-mixed green-yellows
    • lead white and titanium white (for the final highlights)
    • raw umber and a burnt sienna/ultramarine blue mix for the background and shadows.
  5.  I kept the dark areas thin, and slowly built up volume in the light areas.
  6. Finally, I softened the edges, bumped up the chroma in the brightest areas, and added highlights.

The images below show some of the steps.

Please click on an image to see a larger, undistorted version.

Brass Kettle with Lemon — On Copper

This is still a work in progress but the experience hasn’t been exactly what I expected…

  1. On regular paper taped to a drawing board, I drew the setup, as usual. This way, I could correct my mistakes and, by covering more area than I needed, I could decide how exactly to place the drawing on the 10″ x 8″ panel.
  2. Then I found I could not transfer the drawing the way I normally do, by coating the back of the paper with charcoal, placing it over the panel, and then tracing over the drawing.  The charcoal wouldn’t transfer and stay on the copper.  Nor would white chalk. So my solution was to coat the back of the paper with raw umber paint.  Enough of it transferred to the panel so that I could see the lines.
  3. Whenever I transfer a drawing, I often create an monochrome underpainting next — burnt sienna, for example, if I want a warm glow to come through everywhere.  But with the natural shine in the copper, I didn’t think this would be necessary.  An underpainting also helps me block in the large shadow and light shapes as well, keeping them as two separate worlds.  I kept that in mind while moving on to the next stage.
  4. I began the painting by trying to apply the local or “dead” colour directly, starting in the darks, and to do so in thin, transparent layers.  I would stare at the background behind the kettle, for example, and try to approximate the hue, value, and chroma  of what I was seeing in front of me on the palette first… It’s always an approximation on the first go…  I discovered that soft brushes work far better than bristle ones — what I’d normally use early on.  The bristle brushes left streaks and ridges, something I didn’t want left behind so early on.  Every layer became easier to paint after the very first one.
  5. My palette of colours is identical to the one I used in the control painting.  But I applied thinner, transparent layers in all areas except those receiving the most light (especially the lemon, the lemon piece and the highlights on the kettle).

At the time of writing this (November 7, 2019), I’ve modelled all of the elements in the still life and the colour is where I want it to be. I still need to soften some edges before I can call it complete.

I have not left any copper exposed.  But up close, I can perceive the copper shining through in the areas where the paint is less opaque.  And the copper panel seems to make my brass kettle seem more authentic.

The images below show some of the steps.  I will post a final version when it’s ready.

Please click on an image to see a larger, undistorted version.