Application example: Preventive conservation of glass objects

Glass may seem robust in everyday use, but the material is actually sensitive to humidity, temperature, and air pollutants. Over time, exposure to these factors leads to deterioration by dissolution of the glass network structure and leaching of the surface region, resulting in crack formation and flaking of the surface. Depending on their material composition, different glass types are more or less susceptible to such damage. It is therefore an important task in conservation to identify glass objects of vulnerable composition before damage becomes visible and take preventive measures of appropriate storage.

To this end, ion beam analytics can provide helpful information by non-destructive determination of the glass composition. The three methods of PIXE (proton-induces X-ray emission), PIGE (proton-induced gamma-ray emission), and RBS (Rutherford Backscattering) are sensitive to different elements and can probe different material depths with RBS also allowing for depth profiling. A careful combinatory analysis of the acquired data reliably identifies the glass type, even if the object surface has already suffered alteration of its composition by weathering. Investigation of model materials in which weathering has been simulated by exposure to acid solutions help to predict the outcome of certain storage conditions.

By determining the original material composition of historic glass objects in a non-destructive way, ion beam analytics can contribute to their preventive conservation. With reliable information on the material type and its response to environmental factors, conservators can decide on the appropriate required storage conditions for preserving the glass objects.

• M. Mäder and C. Neelmeijer, Proton beam examination of glass – an analytical contribution for preventive conservation.
  Nuclear Instruments and Methods in Physics Research B 226 (2004) 110
  https://doi.org/10.1016/j.nimb.2004.03.086