For effective preservation of historic tapestries
An interdisciplinary consortium of conservation scientists, curators, and scientists focused on improving damage assessment and preservation conditions for historic tapestries at the European level. More specifically, project researchers sought to shed light on the degradation processes in the integral components of the woven structure including wool, silk, metal threads, dyes and mordants. With the aid of integrated chemical/materials science practices characterisation of model and historic samples was achieved. Thereby, using advanced analytical techniques, such as PhotoDiode Array-High Performance Liquid Chromatography (PDA-HPLC) 245 yellow, orange and green historic tapestry yarn samples were studied. The derived results showed that flavonoid dyes, such as weld and DGW were found in 115 of wool samples and in 59 silk samples, while sawwort was not identified. The dyeing process for flavonoid yellow dye sources may influence the strength properties of aged fibres. For the rest of the samples dye sources were difficult to specify due to limited sample size, unknown flavonoid profile, or undyed yarn. Concerning neoflavomoid dyes, logwood, a black dye, was identified in 3 historical yarns and brazilwood, a red dye, in 16 yarns using suitably made marker compounds along with PDA-HPLC analysis. Re-evaluation of the samples was also performed following new information on minor dye component characterisation, along with light ageing and analysis effects on the dyes' chemical compositions. The accuracy in the identification of the original source is a key parameter in damage assessment of tapestries. Dye identification is also highly related to selection of materials (dye source) that reflect availability, and regional and period preferences. These project results involving both well-dated and originated tapestries could be further employed in studies for a broad range of historical textiles.
