The Getty Conservation Institute, the Hirshhorn Museum and Sculpture Garden, and the National Gallery of Art in Washington, D.C., have formed the Canvas Staining Project, a collaborative effort to study issues concerning staining found on unpainted, unprimed areas of canvas in twentieth-century works of art. The aim of this project is to develop safe, well-researched treatment protocols to conserve these works through better understanding of the mechanisms of staining and canvas degradation, and to assess the efficacy of past and current conservation treatments.

The technique of painting on unprimed canvas is most often associated with the Washington, D.C.–based Color-field school, which was active from the mid-1950s through 1970. Artists such as Morris Louis, Kenneth Noland, and Helen Frankenthaler developed a new style of painting that relied on the application of monochromatic fields of color to unprimed canvas. Color-field artists poured, dripped, or brushed thinned paints onto the canvas that soaked through the surface and stained the fabric supports, thereby integrating textile and painting. Many other artists also experimented with painting on raw fabric—nearly every museum worldwide with holdings in modern and contemporary art contains artwork on unprimed canvas.

The texture of the raw canvas can create a velvet-like appearance, and expanses of unpainted canvas form an integral visual component of these works. The exposed canvas, however, is susceptible to readily noticed stains, discolorations, scuffs, and marks. Most of these stains are of unknown origin, and those from known sources are formed by poorly understood mechanisms.

Conservation treatments for Color-field paintings are few, and properly evaluated treatments are fewer, even though these issues became apparent while the school was still active. Today, condition and visual surveys of these works, as well as information gathered from conservators experienced with these paintings, highlight the increasingly problematic staining of Color-field paintings and other works on unprimed canvas in museum and private collections.

The great need for improved conservation treatments prompted the formation of the Canvas Staining Project. The project has identified two topics for researching stain mechanisms: stains due to stretcher bars and stains due to sizing agents. Volatile, possibly reactive components within the wood stretcher bars are believed to migrate to the canvas. Textile manufacturers apply sizing agents, such as starch or wax, to yarns to aid the weaving process, and artists have been known to stiffen the canvas by applying hide glue prior to painting.

In January 2006, specialists from the fields of modern paintings conservation, conservation science, accelerated aging, cellulose degradation, and textile manufacturing gathered in Washington, D.C., under the auspices of the Canvas Staining Project, for a two-day meeting centered around the topics of stains due to stretcher bars and sizing agents.

The meeting began with exchanges on various conservation treatments, storage and display environments, and textile manufacturing processes, which significantly informed the subsequent discussions. Among the topics discussed were the potential benefits and pitfalls of accelerated aging for studies of stretcher bar stains and sizing agents, sampling and testing techniques for fiber samples, and sources and uses of authentic sample materials, as well as the need for more detailed surveys of Color-field paintings and other works on unprimed canvas.

The discussions and ideas brought forth at the meeting will help guide the research plan being developed for the Canvas Staining Project.