Earthen Architecture Initiative_Getty Conservation Institute
Assessment of Ethyl Silicate Consolidants for Earthen Finishes
Earthen finishes, found as decorative or protective coatings on architectural surfaces, have been the subject of conservation treatments due to their vulnerability and aesthetic or cultural significance. Consolidation, or the re-establishment of grain-to-grain cohesion, is performed in response to disaggregation which can be disfiguring or destructive to the finishes.
Consolidation treatments for earthen materials began to be used in the 1960s and 1970s. Since this time, ethyl silicates have emerged as a popular but not fully understood treatment. However, despite decades of use of ethyl silicates, it is still unclear how factors such as the composition of earthen materials, their conditions, the consolidant composition, application methodology, or environmental conditions affect the performance of the treated finishes.
The Getty Conservation Institute in collaboration with the Architectural Conservation Laboratory (ACL) of the University of Pennsylvania (UPenn) is assessing ethyl silicate-based consolidants and their effect on various clay-based surface finishes. Ultimately this research aims to provide information to conservators on which ethyl silicates are most appropriate for use with specific earthen finishes and under which conditions they can optimally be used.
Observation with environmental scanning electron microscopy shows the movement of treated earthen finish materials under conditions of fluctuating relative humidity. In this image, a treated earthen wash is viewed at high magnification. Cracks visible here were seen expanding and contracting as the relative humidity was raised and lowered. Photo: Eric Doehne, GCI