Developing a non-invasive tool to assess the impact of oxidation on the structural integrity of historic wool in Tudor tapestries

Abstract

Near infrared spectroscopy (NIR) can be a useful diagnostic tool in the assessment of quality in textile, agricultural and various other industries. In cultural heritage applications, NIR as a non-invasive assessment tool is advantageous for understanding the composition or degradation of fragile historic objects that cannot be sampled. The direct interpretation of measured NIR spectra is complicated by overlapping bands produced from overtone and combination bands of chemical bonds. However, in combination with multivariate partial least squares (PLS) models and principal component analysis, the physicochemical properties of historic materials can potentially be identified by calibrating against a measured component. In this research, wool fibres from a sacrificial collection of historic tapestry fragments housed at Hampton Court Palace were analysed. The cystine oxidation products of historic wools which can be related to the embrittlement of fibres and ultimately fibre loss, were recorded using Fourier transform infrared (FTIR) spectroscopy. A PLS predictive model was then developed using previously measured NIR spectra for the same historic tapestry fragments to predict the ratios of the cystine oxidation species in historic wools measured in this research. The prediction of a validation set of historic tapestry fragments with known oxidation product ratios was found to be accurate to root mean squared errors of prediction (RMSEP) of 0.11 for cysteic acid/cystine dioxide, 0.03 for an oxidation ratio of cysteic acid/cystine monoxide and 0.06 for cystine dioxide/cystine monoxide. The model was applied successfully to an independent set of historic tapestry fragments with unknown oxidation ratios with an M-distance pass limit of 3. The models were also applied to NIR measurements of historic tapestries on open display with limited success. Alternative methods to investigate and account for errors in this research are proposed. The potential for NIR to be used by conservators as a non-invasive tool for the assessment of textiles, complementing current condition audit practices in use at heritage institutions is also discussed.

Effect of manufacturing temperature and storage duration on stability of chemically defined media measured with LC‐MS/MS

“…There are several potential reactions that could explain this observation. First, l ‐cystine could further oxidize to cystine monoxide, cystine dioxide or cysteic acid in ambient air conditions . Secondly, prolonged storage time could facilitate metal complex formation of l ‐cystine .…”

“…First, L-cystine could further oxidize to cystine monoxide, cystine dioxide or cysteic acid in ambient air conditions. 53 Secondly, prolonged storage time could facilitate metal complex formation of L-cystine. 54 Finally, L-cystine could indeed be reduced to L-cysteine due to negative oxidative reductive potential of CCCFM (unpublished data).…”

Recent developments in using the molecular decay dating method: a review

“…33,[74][75][76] FTIR spectroscopy proved the oxidation of disulfide bonds as a matter of oxidation in the wool of historic Tudor tapestries. 74 Different conservation oils and ointments lead to different status of conservation statuses in terms of surface and mechanical properties of Copt mummies from the first Christian era. 75 Owing to the limited number of artifacts, there is still no concise picture, but the individual chemical composition of materials from different species leads to diverse degradation pathways.…”

“…Historic hair is found in the archaeological context with mummies and might be often overseen in excavations. Not only textiles and tapestries but also plasters contain hair 33,74–76 . FTIR spectroscopy proved the oxidation of disulfide bonds as a matter of oxidation in the wool of historic Tudor tapestries 74 .…”

Characterizing historical textiles and clothing with proteomics

“…Physicochemical damage of wool and silk in indoor environments was assessed using dynamic mechanical thermal analysis (DMTA) together with thermogravimetry (TG) and differential scanning calorimetry (DSC) [81]. Cystine conversion into oxidation products such as cysteic acid in wool has been followed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy [82] and near infrared spectroscopy (NIR) [83]. Fibroin degradation in silk has been assessed by ATR-FTIR [84], NIR and High Performance Size Exclusion Chromatography (HPSEC) [85][86].…”