Conservation of Artists Materials: Workshop Notes and Impressions

This article originally appeared in the CARFAC Saskatchewan Newsletter in May 2007.

I attended the Permanence of Artists’ Materials: Paintings and Works of Art on Paper workshop presented by the Canadian Conservation Institute (CCI) in Saskatoon in March. The workshop was given by two CCI conservators: Debra Daly Hartin, a specialist in paintings, and Sherry Guild, whose expertise is with works on paper. The CCI is an agency of the Department of Canadian Heritage, and was created to promote the proper care and preservation of Canada’s cultural heritage and to advance the practice, science, and technology of conservation.

The topic covered by this article is much too extensive for the amount of space I have been given. In fact, two full days of workshop time were only enough to scratch the surface of the subject, and that was without exploring the 2-inch binder of reference material that was given to each workshop participant. In this article I’ve included highlights of what I found important.

My primary goal in attending the workshop was to have access to these experts for some fairly specific questions about inkjet prints, as well as to confirm my conclusions about the projected longevity of some of my pieces in more traditional media.

I went to the workshop with a fairly good idea of the general issues in conservation, and expected that a lot of the material covered would be a refresher course for me rather than providing a great deal of new knowledge. I found that my expectation was confirmed, and that a number of the other participants who have been practicing artists for a number of years also felt that much of the workshop was a review. However, the refresher was good, and there was enough new information for me to feel that my two days at the workshop was time well spent. As for my questions about inkjet prints, because the workshop focussed on traditional media, I came away with some general answers and the tools to find out more information.

In talking about the workshop—both before and after attending—I discovered that conservators have a less than stellar reputation among some artists. Such statements as “conservators are materials fascists” or “once you’ve talked with a conservator or two you’ll never want to paint again” were not unusual. I found myself defending the conservators not because I took their word as gospel as much as because they were clear in their presentation that their advice was just that: advice. Their job as conservators is, of course, to preserve—and in some cases restore—the products of artistic practice. And having been in contact with what are probably some of the worst cases of art materials failure, they prescribe informed decisions rather than trying to force artists to or away from specific materials. They suggest an educated choice in materials.

This advice to make informed choices of art materials puts me in mind of Rabo Karabekian, the narrator of Kurt Vonnegut’s 1987 novel Bluebeard. Karabekian is a fictional abstract expressionist painter—possibly inspired on Barnett Newman—whose large canvases were created with a combination of a revolutionary-for-the-time new household paint, with coloured tape applied to the surface in vertical bands. According to the story, Karabekian became an art-world laughingstock because not only did the paint he used decompose into toxic gases when exposed to air, it also had a tendency to completely detach itself from its support. These enormous blank canvases were the result of using a paint that was claimed by its manufacturer to “outlast the smile on the Mona Lisa,” and serve as a warning to approach manufacturers’ claims with a grain of salt.

We started off with a lecture on what can go wrong with paintings over time, and were advised to take proactive steps to ensure the longevity of our artworks. Specifically, it was recommended that we choose materials and techniques known for their permanence, and to take steps to eliminate as much as possible the chance of deterioration over time. Part and parcel with this advice to be proactive was an overview of what forces can damage works of art. Among these are radiation (including light), humidity (fluctuations, too much, or too little), temperature (rapid changes, too high, or too low), mechanical damage, pests, and inherent vice of the art work. Inherent vice is the tendency of material to deteriorate due to the essential instability of the components or interaction among components.

Over the course of the workshop there were many questions from participants about specific materials combinations. Most of the CCI answers were generalities or fell back on advice to hold to tradition. Few questions were answered with an unequivocal yes or no. This lack of specific answers has less to do with a conservative approach to materials, and more to do with the fact that there are so many different artists’ materials, so many techniques, and because a great number of these materials and techniques have not been in use for long enough for anyone to be able to make accurate predictions.

The overall advice of the CCI can be summed up as follows:

  • know your materials
  • prepare your supports properly
  • don’t mix different brands
  • follow manufacturers’ directions
  • for media/materials/processes that have a long history, use tried-and-true techniques
  • learn how to do your own materials testing
  • for unproven materials or methods, do your own testing, and expect or plan for the worst

I’m going to go out on a limb here, and say that if you take conservators’ advice to the letter, all artists working in two dimensions should only use oil paint on panels made from quarter-sawn wood. Now, this might seem excessively restrictive. Taken out of context it would seem to confirm the poor reputation conservators have among artists, especially artists who want a more freedom of choice in their materials. But this prescription has nothing to do with the inherent virtue of these materials or the inherent vice of any other medium. Rather, it has to do with what is known. The reason anyone can make such a blanket statement about what lasts is the fact that most of the newer materials simply haven’t been around long enough for anyone to know for sure how they will behave over time. No conservator—or anyone else—is going to be able to make definitive statements about the longevity of acrylic paint. Or plywood. Or plastics. Papers, inks, pastels, and other materials have been with us as long as oils and panels, but many are known to have poorer longevity.

The more general—and more practical—advice is to understand the materials you are using and from this understanding estimate their longevity. Rather than saying “don’t mix oils with acrylics” the advice seems to be something along the lines of “understand that oils and acrylics have different bonding characteristics, and as such may separate over time. And by the way, here are some examples of catastrophic paint failure.” Much as good financial planners will avoid one-size-fits-all solutions, conservators make different recommendations based on the goals, aesthetics, and intended use and life span of art works. Simply put, deviation from traditional methods can shorten a piece’s life span.

Testing is recommended prior to integrating new or unproven materials or techniques into your practice. In some cases it is as simple as checking the ASTM (American Society for Testing and Materials) information for the material, but often you’ll have to do your own tests. Whether this means lightfastness testing of paint, or making a sample piece and exposing it to the elements, or even engaging in deliberately destructive testing depends on the situation. Sherry Guild recommended an article on the web site of acrylic paint manufacturer Golden Paints, which has excellent information on doing your own lightfastness tests on their web site. I’ve provided a link to the site at the end of this article.

Doing your own testing of materials is also recommended because manufacturers’ labelling is not always informative or accurate. Also, many artists use materials that were never intended—or tested—for artist use. For example, outside of the art context, “permanent” ink refers to its insolubility in water rather than its lightfastness. Most reputable art supply companies give some idea of the lightfastness of a given paint, but this rating may be exclusive to a specific company, or may not be specific enough to allow an informed choice. This is not to say that we should distrust manufacturers. Rather, we need to understand that paint companies test random samples, and that there may be deviations. In fact, in The Wilcox Guide to the Best Watercolor Paints, Michael Wilcox documents his exhaustive tests of watercolour paints from the leading companies. Wilcox found that some of his results contradicted some manufacturers’ claims.

General Practical Advice

Most traditional artist materials—canvas, paper, wood panels, even plywood—are hygroscopic, meaning that they tend to absorb moisture from the air. This means that they expand and contract depending on the ambient humidity. Minimizing exposure to fluctuations in humidity through framing, glazing, or encapsulation can go a long way towards preserving a piece. If the display or storage conditions of artworks are known in advance, preventive measures such as the following can be taken:

  • minimize exposure to high levels of light, especially ultraviolet light, via placement, exposure time, or UV-protective glass or varnish
  • protect works from physical damage by framing them
  • choose archival storage containers, such as acid-free boxes
  • avoid chlorinated plastics for storage, as the presence of chlorine can lead to acids being formed

Beyond the basic advice of choosing good quality compatible materials, there was specific practical advice for painters and for artists making works on paper. Granted, there is some overlap such as painters who work on paper, and artists who use paper collage on canvas or other traditional painting supports.

Practical Advice: Paintings

  • Prepare the support properly. In some cases, such as oil on canvas this means protecting the support from the chemical properties of the paint.
  • With smooth supports such as masonite—also known as hardboard—it is advisable to not only degrease the panel but to also roughen the surface slightly so that paint can adhere better. We were shown as an example a painting on masonite which had cracked and then released itself from the support because of flexion of the board, which could have been prevented at the painting stage by roughening the surface, or at the framing stage by stabilizing the board or framing less tightly to account for expansion and contraction.
  • With paintings on canvas it can be helpful—especially in very dry conditions—to either line the painting (attach a second piece of canvas to the back of the painting) or to enclose the back of the painting by attaching one or more pieces of coroplast to the stretcher (or its subdivided sections in the case of large canvases). Creating an enclosure like this creates a more uniform environment for the canvas, thereby minimizing rapid fluctuations in humidity and temperature.

Practical Advice: Works on Paper

  • Choose paper that is acid free, and buffered to a slightly alkaline pH. In the past, lignin—found in most wood-based paper—was believed to be bad. As such, the recommendation was to only use paper made from 100% cotton rag. However, recent research indicates that lignin might not be as bad it was once thought.
  • Avoid papers which have optical brightening agents (OBAs). OBAs behave differently under different kinds of light. Most respond to ultraviolet light in much the same way that certain laundry detergents brighten white clothes. As such, the appearance of works framed with UV-blocking glass—or displayed under minimal-UV lights—will depend on the viewing conditions. Additionally, OBAs can deteriorate more quickly than the paper or pigment.
  • Ideally, works on paper should be matted and framed with conservation-grade materials. Unframed works should be stored flat.
  • Avoid moisture. Avoid bright light. Avoid temperature changes.

Note that some of the advice of conservators contradicts artistic intent, or ease of handling. For example, varnished or enclosed paintings usually look totally different than bare paint. As well, conservators don’t like artists to use fixatives on friable media (that which can be rubbed off, such as pastels or charcoal) even though this eases the handling and storage of such works. In fact, one of the workshop participants was an art preparator at the Mendel. Her take on fixatives was that they greatly ease the gallery’s job.

Everything eventually degrades and disappears. It’s the job of conservators to slow down that process, or to repair damage caused by time. My impression of the conservator’s attitude towards artists is that we need to understand our materials and processes enough to make informed decisions about how we will work, and the impact of these decisions on the longevity of our art works. If our practices involve using new materials, or old materials in new ways, or anything beyond what is known, then we need to understand that there are inherent risks-to-longevity of such practices. Rather than working blindly, it is recommended that we test unknown methods before using them in the creation of real artworks. At the very least, we need to be aware that living today on the bleeding edge of art material alchemy has a good chance of keeping future generations of conservators gainfully employed.