When analysing a given object it is possible to arrive at its material composition and thereby gain an answer - if in doubt - to what sort of artefact is being dealt with. Initially, it is often possible to determine the material on the basis of the conservator's experience and knowledge of materials.
Methods of analysis fall into two groups: Organic and inorganic analysis. There are innumerable methods of analysis, many of which require complex equipment. At the Preservation Department we have various microscopes, special equipment and a chemical laboratory that can be used for our work.
Waterlogged wood normally has a brown-grey colour and can be hard to immediately determine, but by cutting a thin cross-section of the wood and examining it under a screening microscope it is possible, with the aid of a reference work, to determine the type of wood.
Cross-section of oak, micro-photograph
Textiles can be identified on the basis of a single fibre removed from the object and observed under the microscope. As far as animal and vegetable fibres are concerned, each material - as with wood - is characterised by different 'micro-details'.
Synthetic textile materials are made of polymers, often called thin plastic strands, which can easily be recognised as such. Closer identification of the type of plastic, however, calls for further chemical and physical tests.
Metal can be determined on the basis of a wet-chemical analysis - a so-called spot test. But if a very exact analysis is required, equipment such as a Scanning Electron Microscope (SEM) is needed. Such an analysis can be purchased from larger institutions.
Polished, etched section of a Viking knife. At the centre the tempered steel core
Furthermore, metal can be analysed with a so-called polished section. A small slice is cut out of an object using a fine saw, after which it is embedded in epoxy and ground/polished to a high-mirror finish. The section can then be analysed under a microscope.