The implementation of ion chromatography as a key analytical technique for investigation of unstable glass in museum collections

Conservators often face problems in identifying chemically unstable glass objects in museum collections before changes in appearance occur. This paper describes the development and application of an ion chromatography protocol aimed at identifying unstable glass in museum collections before visible changes appear, based on the build-up of ions on the glass surface as a result of deterioration processes induced by atmospheric conditions. The suitability of different types of swabs for sampling surface deposits from unstable glass was investigated. A validated method, using polyester swabs as the sampling material, was applied to objects from Museum Boijmans van Beuningen. Analysis of museum samples indicated that a distinction could be made between stable and unstable glass objects based on the sodium, potassium, acetate and formate concentrations. The outcomes of this study allow for the further investigation of unstable glass using ion chromatography as a key analytical technique and the development of an early warning system for unstable glass.