Poulticing Guidelines for Conservators

The Desalination of Porous Building Materials project developed poulticing guidelines to help conservators working on historic stone structures use less water to remove more salts from stone in a time-effective manner. This was accomplished by better matching the poultice properties and application method to the stone’s substrate and environmental conditions. This is important because using less water may actually remove more salts and result in more predictable extraction. The guidelines the Conservation Institute developed are based on a firm foundation of laboratory research and case studies.

Project laboratory research focused on experiments to characterize the working properties and behavior of poultice, discovering, for example, that shrinkage is a key parameter since it controls the detachment of the poultice from the substrate. Experiments using NMR have documented the behavior of poultices in contact with substrates of contrasting pore size distribution, showing that the pore size of the poultice needs to be matched to the substrate for efficient salt removal. The Institute contributed to these experiments with IC and ESEM analyses.