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Analysis of ancient fibres by LOW VACUUM SCANNING ELECTRON MICROSCOPY/ENERGY DISPERSIVE SPECTROSCOPY (LV-SEM/EDS)

By: Ulrich Schnell, The National Museum of Denmark, Department of
Conservation, Brede,    DK-2800 Lyngby, Denmark.
 

Abstract:

The introduction of  LV-SEM/EDS as a tool in the analysis of ancient fibres has greatly improved
the possibilities of analysing a wide variety of specimens in a non destructive manner. The primary
advantage is that the samples need no coating with a conductor. The poster presents a number of
examples of how LV-SEM can produce more valuable information about the fibres than is
possible with conventional SEM, and with minimum damage to the artefact.

Fibre analysis in conservation science is crucial both for identification of the material,
identification of the techniques applied to the material as well as revealing fraud.

The minimum sample preparation required for the analysis, and hence the minimum handling of
the specimen, makes it possible to analyse single deteriorated fibres. Furthermore the often
unique, small and fragile specimen is left unaltered for further work.

Moreover the technique makes it possible to analyse a sample with a higher content of volatile
constituents than is possible in conventional SEM, because a high  vacuum is not necessary. It is
thus possible to take archaeological samples directly from the excavation site to analysis under
LV-SEM and thus avoid manipulation that may destroy the specimen. The analysis of a piece of
13th century textile excavated from a grave illustrates this.

Altering the pressure in the chamber and the power of the electrons offer a possibility to analyse
both internal and external structure without making a cross section. Examples of reindeer hair and
silk are presented

Finally LV-SEM has been used to distinguish original paper fibres from fraudulent objects, on the
basis of the character of the fibres and the additives. An example of 13th century Asian paper
fibres is shown.

The  experiments were performed on a JEOL 5310 LV SEM with a Link EDS system using a
Si(Li) ATW detector. The instrument is located at the School of Conservation  of the Danish
Royal Academy of Fine  Arts, Copenhagen, Denmark.

If you have comments on this home page, or any kind of professional interest in our work please feel free to contact me at ulrich@alfheim.dk or phone me at +45 33 47 35 28.
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