As soon as the Le Corbusier’s Unité d’Habitation kitchen arrived in MoMA’s sculpture conservation lab, we began assembling the various components to assess and document their condition. Once that was done we were faced with an object that had been re-painted as many as six separate times while it was still in use. After discussion with the curators, the decision was made to remove that overpaint in order to better present Le Corbusier’s original design and palette.
Before we could begin to develop a treatment plan to remove the paint we needed to understand what type of paint was there, how well attached each of the layers were to each other, and if any of the original paint was left to uncover. Microscopy, chemical analysis, photo documentation, and archival research became our primary tools in this endeavor. Over the course of the next month each piece of the kitchen was photographed and samples of all the painted surfaces were taken for cross-section analysis. Cross-section analysis was particularly helpful in starting to determine the condition of the original paint surface.
A paint cross section is a sample of paint a millimeter wide that goes from the top surface of the paint down through each layer of paint to the bottom material, called the substrate, which in the case of our kitchen is the wood. This chip is embedded in polyester and polished giving us an image of every layer of paint present on the surface.
The photo below is an example of a cross section from the front of the red sliding door on the front of the bar; layer 1 is the oldest layer of paint present. When we compared this layer to the Le Corbusier palette endorsed by the Corbusier Foundation it was a close match the red ochre shade.
After analyzing the results of our cross sections we compared these results to documentation at the Corbusier Foundation in Paris. Le Corbusier had developed a specific palette of colors for the kitchen along with instructions on how each of the colors should be used. However these instructions were not rigid, and there was variation from kitchen to kitchen. For example he left guidelines that one of the sliding panels over the stove be painted while the other panel should be varnished. The painted cabinet could be either green or red ochre. We determined using cross sections that the left slider of the MoMA kitchen was originally painted green.
Cross sections are a remarkable tool to see the history of an object, where all the layers of paint are laid out like layers of archeological strata. However, there are some drawbacks. These are small samples, at the very most a few millimeters, and the surfaces in this kitchen are massive in comparison. Further, conservators tend to sample in areas that are already chipped, rather than create new areas of loss. It was difficult to know if our samples were taken in the exact spot where the original surface was still present. Therefore as we treated the kitchen by methodically removing upper layers of paint we also worked with our scientific research department to analyze the newly exposed paint layers in order to distinguish layers of modern paint, which wouldn’t have existed in 1953, from the older paint layers.