By Jeffrey Levin
In the centuries before the Industrial Revolution and the development of manufactured paints, a painter was not only an artist, but also a kind of chemist. Mixing pigments with selected binding mediathe material which holds the pigments together and bonds paint to surfaces the painter personally created his or her paints.
Artists often followed a variety of traditional paint recipes. Later, differences in paint formulas proliferated as painters experimented with a multiplicity of binding media, seeking that special combination that would give their work greater luminosity or warmth or life. With the advent of commercial paints, most painters no longer concerned themselves with detailed knowledge of the components of the paints they used.
Variations in paint composition present a formidable challenge to the modern conservator. Before embarking on the cleaning or restoration of a painting, a conservator analyzes the composition of the paint layers. Using a number of modern analytical techniques it is relatively simple to identify inorganic pigments. Binding media, however, remain much more difficult to analyze.
To remedy that situation, the GCI is engaged in a three-year project applying recent technology to binding media analysis. As part of that project, the GCI has assembled material to form one of the most comprehensive research collections of binding media now available.
A comprehensive collection is arduous to create since standard materials of historical binding media are not available commercially. But its value as a resource is immeasurable because it provides the samples necessary to help establish analytical standards.
The GCI binding media collection is the result of a joint project with the Center for Conservation and Technical Studies (CCTS) at Harvard University's Fogg Art Museum. Researchers from both groups worked together assembling a computer database catalog of the Museum's Gettens Collection of Binding Media. Some of the deficiencies in the Gettens Collection (e.g., inadequate sample information, unmonitored storage conditions, erratic sample exposure to light and heat) convinced the GCI of the need for a new binding media collection.
The GCI collection, located at its headquarters in Marina del Rey, California, presently. contains approximately 800 samples of primary materials used as binding media. These include oils, natural resins, waxes, animal glues, gums, and polymers. The collection also contains approximately 900 binary mixtures (e.g., egg and oil) in varying proportions, with and without pigments. The collection is stored in two ways. A large portion of materials are housed in airtight, amber glass containers labeled with basic information and a computer barcode which is the key to a computer file of complete information. Another portion of the material is processed for coating, applied to 4" x 5" glass plates, stored in the dark and allowed to age. Like the glass containers, each plate is labeled with basic information and a computer barcode. Most of the samples have already been analyzed using infrared spectroscopy.
The binding media collection continues to grow through the contributions of interested individuals and institutions. Expanding the collection to include binding media from around the world is essential. Even the same material can have different properties depending on the geography in which it was found, the season in which it was collected, and the manner in which it was processed.
The long-term objective is to provide future generations of conservation scientists with a valuable collection of well defined standards, test materials, and experimental samples. Those wishing to contribute materials to the library, or desiring more information. should contact Dr. Dusan C. Stulik, Deputy Scientific Program Director, the GCI.