Protection and relocation of frescoes during construction at the Harvard Art Museums

Abstract

Three frescoes painted in the 1930’s by social realist artists Lewis Rubenstein and Rico Lebrun needed to be consolidated, protected and moved during major renovations to the Harvard Art Museums between 2009 2 and 2014. During construction, the frescoes, measuring a total of 22.3 m , would be subject to relocation, shock and vibration, climate extremes and structural intervention. Conservators devised a cyclododecane (CDD) facing as part of a multi-layered system of protection designed to remain in place for several years. Two of the fresco walls, weighing many tons, were cut from the existing masonry and moved by crane, while one of the frescos remained in situ on the inside of an exterior wall, protected from the elements by a purpose-built housing. The project allowed comparison of two techniques for applying molten CDD on a large scale: by spraying through a gun designed for hot-melt glue, and by painting with hog hair brushes. Ultimately, brushes proved quicker and easier to use. Testing at various temperatures revealed new information about CDD’s behaviour. Though it reportedly melts at 60–71°C, it was significantly more fluid and easier to apply during testing in the 80–85°C range. Heating the CDD above 85°C using a hot glue gun resulted in samples that became tacky shortly after application. FTIR analysis revealed changes in the aliphatic stretching and bending regions of CDD in these samples. The analysis suggests that CDD can be safely heated to 80°C without causing molecular changes. The CDD facing successfully preserved the fragile fresco surfaces, remaining intact under a Marvelseal barrier film for over three years. Upon removal of this protective seal the CDD completely sublimated with the help of fans, localised heating and ventilation.