90 Chapter 4
5.4 Assessing the Condition of Wool by Microanalytical Techniques
Electron microscopy can provide valuable information about morphological
changes in the fibres, and can potentially give an indication of the nature and
cause of degradation, such as photolytic damage, swelling, desiccation or abra-
sion. The appearance of fracture surfaces is a particularly useful source of
information.
Amino acid analysis is also potentially of value in monitoring and assess-
ing deterioration. By following the way in which the proportions of various
residues vary over time, it is possible to gain an understanding of the type of
damage that has occurred to the fibres: e.g.the cystine disulfide bridge is
particularly susceptible to photo-oxidation, and this reaction is accompanied
by a corresponding increase in cysteic acid, a process which can be followed
using this type of analysis.
Chromatographic techniques may also reveal a range of important data. End-
group analysis will give an indication of the breakdown of the peptide chain,
and the measurement of extracted soluble protein will similarly indicate the
extent to which the polymer has deteriorated. These techniques, alongside
mass spectroscopy, can also reveal the presence of dyes and other treatments.
5.5 Conservation and Treatment of the Tree of Jesse Tapestry
An approach of minimal intervention was taken for the conservation treat-
ment and subsequent mounting of the tapestry. Gentle vacuum cleaning was
employed to remove the particulate soiling, which, if left in place, may have
caused abrasion. Those earlier repairs and alterations that were in good condi-
tion were left intact; only those which were found to be unstable were treated.
The calico lining, which joined the frontal to the superfrontal, was removed, as
this was not thought to have any historical significance, and this enabled differ-
ent support methods to be employed for the two pieces, suitable to their indi-
vidual requirements – the Nativity scene on the superfrontal, for example was
reinforced with a linen patch. Both sections were then stitched to conservation-
quality boards to provide protection and long-term stability, and to limit the
necessity of further intervention. Pest monitoring was recommended as a
long-term strategy, due to the particular susceptibility of wool fibres to attack
by insects.
6 Conclusions
We began this chapter by suggesting that a conservation scientist would need
a thorough appreciation of the underlying science to best advise on the long-
term preservation of historic artefacts like the Victorysail, Shackleton’s ensign
and the Jessetapestry. In the associated investigation carried out to support