Salt mixtures phase equilibria: a tool of preventive conservation against salt weathering

Document Type : Original Article

Authors

1 Hashemite University, Zarqa, Jordan

2 Hellenic Ministry of Culture, Athens, Greece

Abstract

Coastal architectural heritage is contaminated by sea spray which constitutes a multi salt solution. The thermodynamic assessment of salt mixtures has been recently suggested in order to predict optimal conditions for preservation against salt weathering. This development in the form of the computer based model ECOS has been used as a diagnostic tool at the coastal archaeological site of Delos. Despite the dominance of halite as the main contaminant, quantitative analysis of the salt content in two monuments revealed significant variety due to fractionated infiltration and secondary contamination by ground moisture capillary rise. The thermodynamic assessment, comprised by phase transition diagrams have been correlated to the monitored environmental conditions. The results underline the role of minor species in the generation of damage and the importance of the halite-gypsum mixture. The investigation provided arguments for the application of environmental control along with data that can be used in various conservation treatments.

Keywords