Laser cleaning at the Isabella Stewart Gardner Museum, Boston, USA: Sixteen Roman sculptures, fourteen months, and three conservators

Abstract

In 2011, the Isabella Stewart Gardner Museum conservation staff embarked on a project to clean the freestanding, ancient Roman marble sculptures in the center of the Museum's iconic courtyard. The goal was to remove accumulated ingrained dirt and surface accretions from these prominent sculptures. Prior cleaning tests indicated that the use of a Q-switched Nd:YAG 1064 nm laser unit resulted in controlled and uniform cleaning of the marble surfaces. Sixteen sculptures were cleaned by a team of three objects conservators. Six of the sculptures were portable and were cleaned in a laser-safe room within the conservation facilities; however, the remaining 10 sculptures are installed permanently into the building structure and, thus, had to be cleaned in situ. The condition of the marble surfaces was extremely varied. Some retained evidence of polish, and some had severely unstable intergranular structures. Laser cleaning was especially effective at reducing dirt from the unstable marble surfaces, whereas any traditional cleaning methods could have caused staining or loss. Significantly, the laser application was also successful in reducing iron-stained calcareous burial accretions. The success of this project has encouraged the Gardner Museum conservators to continue laser cleaning additional Roman marble sculptures in an adjacent gallery.