Understanding Salt Crystallization and Decay

Efforts to reduce salt concentration in order to lower the rate of decay caused by crystallization are a common—and critical—component of conservation measures. As part of the Salt Research project, various approaches to salt reduction—such as poulticing, rinsing, and sacrificial rendering—were tested and monitored analytically. Tests were carried out in the Conservation Institute laboratories and were validated in the field in order to evaluate the efficiency of various treatments and to estimate the risk of secondary damage to highly salt-laden surfaces.

Although conservation treatments take place on a macroscale, salts begin to crystallize in pores on a microscale. For that reason, the project coupled the use of time-lapse video microscopy and environmental scanning microscopy for an in situ dynamic study of salt crystallization and dissolution. This aspect of the project provided important knowledge of the underlying mechanisms of decay.

Finally, visualizing the processes involved on a micro-level has contributed to the education of conservation professionals by increasing their understanding of decay processes. The project developed and disseminated educational tools and information—including visual materials depicting salt crystallization and dissolution—that have enhanced the collaboration between conservators and researchers in the field of salt damage.