Characterization of historic silk by polarized attenuated total reflectance Fourier transform infrared spectroscopy for informed conservation

Description/Abstract

When assessing historic textiles and considering appropriate conservation, display and storage strategies, characterising the physical condition of the textiles is essential. Our work has concentrated on developing non-destructive or micro-destructive methodologies that will permit this. Previously, we have demonstrated a correlation between the physical deterioration of unweighted and ‘pink’ tin IV chloride weighted silk and certain measurable spectroscopic and chromatographic signatures, derived from polarised FTIR-ATR spectroscopy (Pol-ATR) and HPLC microsampling analyses. The application of the Pol-ATR technique to aged silk characterisation has now been extended to include a more comprehensive range of weighting methods and ageing regimes. This was intended to replicate the full spectrum of states of deterioration observed in silk textiles, from pristine to heavily degraded. Breaking strength was employed as a measure of the physical integrity of the fibres, and, as expected, decreased with ageing. An orientational crystallinity parameter, reflecting the microstructural ordering of the fibroin polymer within the fibres, was derived from the Pol-ATR spectra. A good correlation was observed between the breaking strength of the variety of fibres and this parameter. This suggests that the physical state of historic silk fabrics might be adequately characterised for conservation purposes by such indirect micromethodology.