conservation

research & diagnosis

technical analysis of materials

introduction

Diagnosing the condition of an object often begins with a thorough visual examination, carried out with the naked eye, a loupe, a microscope or other techniques. Expertise in the technical analysis of materials is central to this process. This type of examination can reveal various physical characteristics, such as stress, glass thickness, fracture patterns and the morphology of fracture surfaces.

Sound and smell can also play a role in assessing the condition of glass. During the diagnostic process, an object’s vulnerabilities and the conservation issues they present are identified.

Many techniques are available for the physico-chemical analysis of glass, but only a limited number can be applied to cultural heritage objects. This is because sampling, which requires removing a small piece of glass from the object, may not be possible. Sample material may only be available from deteriorated archaeological glass or broken glass objects. Even then, grinding the sample into powder, as required for certain analytical techniques, is rarely desirable. Consequently, the scope for non-destructive analysis of glass objects is usually very limited. Glass reconstructions can sometimes make further analysis possible without sampling the original object.

This platform describes several materials analysis techniques, including microscopy, RTI, XRF and SEM-EDX. Many others could be added in the future. (see also objects.)

When studying the condition of a large glass collection, time constraints can make it impractical to thoroughly examine or continuously monitor every object individually. In such cases, a smaller group of objects selected according to specific criteria can be used to represent the collection. The ‘guide group’ at Museum Boijmans Van Beuningen is one such group of glass objects (some of which can be viewed on this platform). The museum’s entire glass collection was examined and treated in 2013, and the guide group has continued to be monitored in light of those findings. Objects are occasionally added to the group.

Besides regular in-depth research, an institution may also choose to subject objects from a glass collection to a faster form of examination. The Stedelijk Museum Amsterdam developed a method called the Quick Scan Tool for this purpose. All glass objects undergo a shortened condition assessment that focuses on stability and addresses two key questions:
1. Is the object stable in storage?
2. Is the object stable for display?

Where instability is suspected or confirmed, a follow-up study is recommended to conduct a more in-depth assessment of the condition and to examine the manufacturing processes of specific individual objects. Based on these findings, the museum can develop a long-term vision and formulate a conservation policy.

For more information about this approach, contact N. Krumperman, coordinating conservator of 3D Design (collections), Stedelijk Museum Amsterdam.