Introduction:

What is Coade Stone? When was Bakelite invented? What is the chemical structure of indigo? Is it safe to use mineral spirits?  The answer to all of these questions and much more can be found in CAMEO (Conservation and Art Materials Encyclopedia Online at cameo.mfa.org), an electronic database that compiles, defines, and disseminates technical information on the distinct collection of terms, materials, and techniques used in the production and conservation of works of art (Fig. 1).

Content:

CAMEO was developed by the Museum of Fine Arts, Boston, and placed on the Internet in 1999.  The primary CAMEO database combines technical, historical, chemical, and visual information on historic and contemporary materials used in the preservation and production of artistic, architectural, and archaeological artifacts).  With more than 9,000 records, the reference set is broad because artifacts, sites, and treatment methods can include any combination of materials that have been used in the history of mankind.  Additionally, the knowledge required for work in the field of art conservation is becoming ever more complex and technical due to factors, such as increased availability of analytical techniques, better understanding of deterioration processes, wider selection of treatment materials, new emphasis placed on preventive conservation, and ever-growing concerns about health and safety.

Figure 1. View of the Home Page for the CAMEO (Conservation and Art Materials Encyclopedia Online) found at cameo.mfa.org

As may be expected, CAMEO entries includes a full-range of materials in the classes of  pigments, minerals, binders, coatings, adhesives, fibers, dyes, solvents, paints, corrosion inhibitors, woods, pollutants, insects, pesticides, and storage materials.  Each term in the database was selected based on its having been mentioned in the conservation literature regardless of whether its use is now considered good (Paraloid @B-72 at http://cameo.mfa.org/wiki/Paraloid@_B-72, Fig. 2) or bad (DDT at http://cameo.mfa.org/wiki/DDT, or Soluble nylon at http://cameo.mfa.org/wiki/Soluble_nylon).

Examples of other materials and related terms in the encyclopedia that may not be as obvious include:

• Materials used in the production or conservation of historic and processed materials (stainless steel, eosin, Portland cement, plywood, Art-Sorb, acoustic tile, etc.)
• Compositional groups (oil, alcohol, acrylic, aniline dye, polymer, etc.)
• Chemical and physical classes (abrasive, detergent, sealant, absorbent, insecticide, etc.)
• Analytical tools (hygrometer, X-ray fluorescence analysis, infrared spectroscopy, etc.)
• Material characterization terms (hardness, gloss, porosity, refractive index, etc.)
• Selected devices (Solander box, smoke detector, laser pointer, fluorescent lamp, etc.)

Figure 2. An example page for the commercial product, Paraloid B-72, commonly used as an adhesive and coating on art materials.

The primary description pages for each record contain a brief, but comprehensive text about the general class of material along with its major use or biological source.  For a natural product, its native geographical region is listed.  Information is supplied about the material’s production, manufacturer, historical availability, appearance, and uses.  For searching purposes, alternative, foreign, and archaic names are included in a synonym field along with common misspellings.  As part of an international collaboration, several European colleagues from the CHARISMA (formerly EU-Artech) organization of museum scientists volunteered to enhance the content, breadth, and transnational accessibility of the database.  As part of this work, over 10,000 foreign language terms have been added to the synonyms fields allowing for records to be retrieved by their Dutch, French, German, Greek, Italian, Portuguese, or Spanish names. In the past year alone, CAMEO logged over 300,000 page hits in more than 200 countries.  

Because of the condensed format for the CAMEO descriptions, references, such as for review articles, book chapters, and books, are included to direct the reader to more extensive information. Some of the references, such as the manufacturer’s Web pages, cited JAIC articles, and SDS sheets have direct hyperlinks to other Web sites on the Internet.

Images:

Several thousand images have also been added to CAMEO.  The thumbnail images can be enlarged with a click.  These images provide an essential record of a materials characteristics including photographs and drawings of a material’s outward appearance as well as analytical image records of its microscopic and spectroscopic characteristics.

Examples of images in the CAMEO database are:

• Images of artwork from the MFA’s collection that contain the material or have been treated or affected by the subject of record (e.g., see indigo, black walnut, Fig. 3).
• Photographic images or drawings of minerals, gemstones, corrosion products, insects, animals, trees, and plants as well as processed products from these raw materials (e.g., quartz, ant).
• Micrographs of minerals, metals, pigments, wood sections, and fibers, as well as positive and negative microanalytical results for spot tests and fluorescent staining (e.g., oak, cotton)
• UV/Vis, infrared, and Raman spectra of oils, resins, gums, waxes, proteins, pigments, dyes, and polymers (e.g., polyethylene, beeswax, realgar).
• XRD patterns for minerals, pigments, and corrosion products (e.g., calcite, brochantite)
• Comparative charts showing aging studies, stress curves, and product comparisons (e. g.,  see records for blue pigments, gemstone, solvent, and Paraloid.

Figure 3.  Examples of images that are found in the record for black walnut

Development:

In 2013, the CAMEO database was transferred from a proprietary software system and placed on a MediaWiki platform that resides on a cloud server.  This transformation provided two significant changes for the active maintenance and growth of the database.  First, the new platform provided the flexibility to keep editorial restrictions while also allowing easier, wide-spread contributions for revising and expanding the scope and content of our multi-functional information source.  CAMEO currently has 52 editors and that number is continually growing.  In conservation programs, professors have asked students to select a material, research it, then provide a prototype for an updated record including a prioritized citation list for additional information. All scientists interested in adding, updating, and or correcting the database are welcome to contact this author for editorial privileges.

Secondly, the cloud server provides for virtually unlimited growth, which has placed CAMEO in the unique position to offer homes to small collaborative databases that benefit the art conservation and museum communities. Two of the new major information resources are related to the use and analysis of natural and synthetic dyes in works of art. The first resource is the documentation of the Uemura collection of dyed fabrics that was acquired by the MFA in 2008.  A database containing the original Japanese text with its English translation was created by Masumi Kataoka, Sherman Fairchild Fellow in Textile Conservation. Images of all of the dyed samples were collected by Keith Lawrence, Scientific photographer. The second new resource is seminal to the scientific art analysis world because it provides critical analytical parameters for the analysis of synthetic and natural dyes using state-of-the-art liquid chromatographic and mass spectrometric equipment. This database initially will contain analyses carried out over the past ten years by Richard Laursen and collaborators at Boston University, who have carried out extensive work on many natural dye raw materials.  Results from analyses of the Uemura archive carried out by Richard Newman at the MFA will also be included.  It is anticipated that analyses from other researchers around the world will be added in the future, making this CAMEO database an invaluable resource for high-quality information on the compositions of raw dye materials used throughout history, as well as examples of samples from works of art that contain those dyes (see Fig. 4).  

Preventive Conservation:

Why is the technical information in CAMEO important for museums and how it is used?  Identification of materials in art is a significant consideration, but other such as the problems dealt with in the specialized field of preventive conservation can provide some additional insight.  An important goal of museums is to preserve their collections for future generations.  In preventive conservation, the basic guidelines are to provide optimal environments for objects thereby minimizing causes of deterioration; these practices are widely considered critical for the cost effective preservation of large collections and are applied to the objects in storage as well as those on display.

To this effect, when sensitive objects go on display, they are placed in air-tight vitrines, or display cases, to provide physical safety while also creating controlled microenvironments that diminish pollutants, temperature and humidity fluctuations, as well as UV light exposure.  Both high-tech and low-tech

Figure 4.  The pagoda tree bud record in the Natural and Synthetic Dyes database of CAMEO

methods are used to create the environments.  For example, some valuable organic materials, such as the Declaration of Independence, are stored a hermetically sealed cases that use oxygen scavengers tomaintain an anoxic atmosphere.   Also, it is common for %RH in display cases to be buffered at optimal levels using silica gel that has been conditioned to very specific moisture levels using saturated salt solutions.   Controlled humidities are extremely important in many cases, such as where an archaeological ceramic with absorbed salts or corroded sculpture with bronze disease must be kept at low humidities to minimize the formation of salt accretions or further corrosion.  Additionally, vitrines containing objects made of silver, or combinations of metals, may contain sulfur scavengers, such as Corrosion Intercept, to hinder surface reactions. 

Extreme care is used to examine all materials used in display case construction since any volatile components introduced in a contained atmosphere will be higher than levels found outside the case. Since the interior of a display case essentially creates a microclimate for the object, it can be disastrous if the materials used in the construction of the case release pollutants.  For example, a common construction material is wood, but hardwoods, such as oak, release acetic acid, and some laminated woods, such as plywood, release formaldehyde and other reactive compounds.  Vitrines can still be made with wood as long as it is sealed with a barrier film (i.e., impermeable laminating material), such as MarvelSeal 360.  A video on the Marvelseal 360 record illustrates correct method for the application of this heat-seal laminate link to video https://www.youtube.com/embed/C2u7MiOp7jI). 

It is standard practice to test all materials that go into a display case, whether it is the base, gasket, adhesive, fabric, or display label.  For decades, a low tech method, called the Oddy test (http://cameo.mfa.org/wiki/Oddy_test), has been used to evaluate display case materials by placing them in a sealed test tube with small coupons of silver, lead, and bronze then waiting for 6 weeks to see if any corrosion or tarnish occurs.  Attempts to evaluate off-gassing of deleterious materials by other methods, including residual gas analyzers and sorbent tubes have not been successful.  Current hopes are leaning in the direction of a colorimetric sensor array developed by the Suslick group at the University of Illinois at Urbana Champaign that uses an array of chemically reactive dyes targeted at potential pollutants to produce a visual indicator of aerosol problems (LaGasse, et al 2014). 

Summary:

CAMEO is a readily accessible resource that defines, characterizes, and increases our understanding of materials found in historic and artistic works.  It provides a time saving resource for the art conservation field where knowledge regarding material properties, reactivity, and history can be crucial to success and safety.  It also enables all interested persons to access vast amounts of technical and visual material’s data.  This is especially beneficial to labs or museums with limited personnel or resources.  The MFA is committed to providing CAMEO as an outreach program with numerous benefits for professional conservators, the museum community, and the general public.

References:

Maria K. LaGasse, Jacqueline M. Rankin, Jon R. Askim, Kenneth S. Suslick. ‘Colorimetric sensor arrays: Interplay of geometry, substrate, and immobilization’, Sensors and Actuators B (2014) 116-122.