Formation of Acetates on Salt Contaminated Ceramics

Kirsten Linnow¹, Lieve Halsberghe² and Michael Steiger¹

1. Universität Hamburg, Institut für Anorganische und Angewandte Chemie, D - 20146 Hamburg, Germany
2. Ceramics conservation and restoration, 15, rue de Bivange, L-3395 Roeser, Luxembourg

E-mail: lievehalsberghe@hotmail.com

Serious damage of calcareous materials by acetic acid vapour attack has been observed on tiles in museum collections in Belgium. Formation of acetate salt efflorescence on calcareous artefacts is a widespread problem in wooden museum cabinets. Various precipitations from the mixed calcium-acetate-chloride-nitrate system have been observed. Solubility measurements were carried out and several different solids were identified by x-ray diffraction and ion analysis. Application of an equilibrium model allows for the calculation of the invariant points in this quaternary salt system, yielding the complete phase diagram, consisting of ten different solid phases, was constructed. The phase diagram is used to explain of the formation of calcium acetate containing efflorescences.