Signatures of ageing: correlations with behaviour

Decisions on the conservation and display of a textile, including prioritisation for treatment, should be informed by objective knowledge of its current physical state. Measuring the tenacity and elasticity of yarns and fabric, however, generally requires sampling and is necessarily destructive. Bearing in mind the need to maintain the integrity of the artifact, an indirect approach requiring at most the removal of just microsamples is preferred. On ageing, the performance of a natural fibre such as silk or linen is compromised as the components within the fibre deteriorate. There is a reasonable correlation between the reduced tenacity of silk upon ageing and both the shortening of the silk fibroin polymer and the disorientation of the fibroin crystallites. These two parameters can be measured from just a short length of a silk thread using size exclusion chromatography (SEC) and polarized infrared (IR) spectroscopy, respectively. Other destructive microanalyses, e.g. X-ray diffraction (XRD), X-ray microtomography (XRM) and thermomechanical studies, can also offer characteristic chemical and microstructural identifiers. More recent technological advances and applied research suggest the potential for non-destructive approaches to condition assessment; with techniques such as near-infrared spectroscopy (NIR), the sampling constraint is circumvented by monitoring a dependent physical effect such as moisture sorption.