Documenting coupons with a colorimeter. Image courtesy of Joanna Hurd-Morrisey

This research project investigates documentation practices for Robert Rauschenberg’s metal paintings with reflective or mirror-like surfaces. In these series, Rauschenberg used metal sheets as substrates for paintings, pushing the boundaries of traditional painting through the use of artificially-induced “tarnishes” created with chemical patinating solutions and polyurethane “resists.” The artworks are visually active as their reflective properties include the environment and viewer in the presentation surface. A consequence of the reflectivity is that the artworks are nearly impossible to accurately capture in a static image. Throughout the past few decades, the artworks have been photographed in several ways and never, to the author’s knowledge, by a conservator with the sole aim of documenting the artwork’s condition. Due to the reflective nature of the paintings, the photographs always capture some reflections from the environment in the painting’s presentation surface. Sometimes, these reflections were left in the images; other times, they were removed during post-capture processing. In either case, the result was an image that did not record the condition of the artwork. As such, it is difficult to definitively state if and how the artworks have changed over time. 

This investigation aimed to understand what documentation practices can most accurately record the current condition of the artwork so that a baseline can be established. Three techniques for documenting these artworks are experimentally explored: colorimetry, glossimetry, and digital photography. Mockups with artificially-induced patina and glossy varnish coating were created to test the accuracy and precision of the equipment when recording subtle changes. 

Experimental results indicate that accurate documentation of these metal paintings will require a combination of digital photography, colorimetry, and glossimetry. Colorimetry can be used to record color changes over time, but has limitations depending on the size and texture of the space being measured. Glossimetry can precisely record changes in gloss, but different geometries should be recorded depending on the area of the painting being measured. Digital photography is useful for recording larger areas of tarnishes, for capturing topography, and for documenting measurement locations, but alone it is insufficient for accurately and precisely documenting the current conditions, color, and gloss of the metal painting’s presentation surface. 

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