Q. Recently I tried painting on leather with acrylics. The paint went on beautifully, but I’m concerned about any long-term problems between the paint and whatever the leather was treated with.
A. There’s nothing unusual about painting on leather. After all, you can find plenty of examples of painted utilitarian leather objects including horse bridles and such decorative works as gilded and painted stamped leather wallpaper. Historically, however, leather has not been widely used as a fine-art support for painting. There’s probably little advantage to painting on leather, and possibly some technical disadvantage—unless you’re interested in incorporating the color and texture of the leather support in your composition. Most likely the historical disinterest in leather as a support for painting is fueled by this lack of distinct advantage, as well as the cost.
Leather is made from animal skins that have been treated by a tanning process, which makes them resistant to rot. Essentially, tanning agents produce a more stable lattice structure of fibers. The tanning agents have traditionally been obtained from bark and other vegetable matter, as well as through fatty substances and/or smoke as a curing agent. Today most tanning techniques use minerals such as chromium salts or synthetic tannins, which have been available since the early 20th century. In the ideal processing situation, the tanning agents become chemically bound up in the structure of the leather. If, however, there are contaminants or other residues left behind, the character and aging of the leather could be affected. While it’s hard to know the particular tanning process that was used for your piece of leather, I’m not aware of any adverse effects a proper tanning would have on acrylic paint.
Impurities in the leather may not chemically attack your paint, but anything that undermines your support puts the physical well-being of your paint layers at risk. For example, acid and alkaline residues from the tanning process can make leather brittle and subject to cracking. Also, vegetable- or bark-tanned leather is subject to a type of chemical decay called red rot. Red rot is brought on by the presence of sulfur dioxide in the atmosphere and makes leather powdery. Either of these attacks on the leather would obviously jeopardize any paint layer you applied to it.
Leather is also easily affected by such changes in the environment as extremes in humidity. If leather becomes too dry, it can become stiff and brittle and may crack. Conversely, if leather is exposed to very high humidity, it could grow mold, which may etch the surface or bleach it. Other environmental threats include light, which can bleach dyed leathers and may even harm the leather itself. There are also some insects, like the silverfish, that will attack leather. Of course, these types of problems aren’t limited to leather. Extremes in humidity, insects, mold and acidity can affect canvas and paper, too. No matter the support, you should always try to maintain your artworks in a stable environment where there are no extremes of temperature or humidity.
You must also take care to choose a leather support that promotes good adhesion between the paint layer and the support with tooth and a degree of absorption to get a good physical bond. An overly smooth leather, like patent leather, or one that’s too greasy may result in poor adhesion, causing your paint to flake off. Likewise the leather must be stiff enough or well-supported to avoid excessive manipulation of the surface, such as folding, which could also cause the paint to flake off. Keep these requirements in mind for every support you work on.
One final caution concerning the common care of leather: Leather is typically treated with creams or oils during its lifetime in order to maintain suppleness. But you shouldn’t apply any creams formulated for leather care directly to the painted surface because the paint layer will impede the absorption of the cream into the leather and the cream may also leave residues that could discolor or dull the paint surface.
Heather Galloway is a freelance conservator living in northern Ohio.