Evaluation of color degradation on unearthed silks: A data analytical strategy based on microfading spectrometry

Abstract

Silk relics, as the typical representative of organic artifacts, are important historical materials for the study of Chinese and world culture. However, these relics are extremely vulnerable to burial or conservation environments which play a crucial role in its acceleration of deterioration. Light-induced color degradation is one of the most serious threats to textiles, resulting in regional fading of these objects. This special threat severely affected their artistic and historical values and produced irrevocable alteration. The evaluation of discoloration of dyed silk relics has been the hot spot of conservation science. Therefore, the regional lightfastness assessment of textile artifacts has been of significance for their color preservation. Recently, microfading spectrometry has been broadly applied for simulating accelerated photofading process and evaluating if the pigment or dye was susceptible to discoloration. With the goal of finely demonstrating color changes in multiple dimensions, the integrated data analytical method is of great necessity. In this work, a data analytical strategy has been developed for elaborately evaluating the fading behavior of dyestuff from the spectral, kinetic, and chromatic aspects with their color change trajectory also provided. Based on the strategy, 10 representative vegetable dyes have been studied. Furthermore, the potential fading behaviors of 3 groups of dyed silks unearthed from different places of Keyakekuduke beacon tower site, Xinjiang were evaluated, compared and predicted. From the results, it was demonstrated that archaeological silk objects unearthed from different places of one site may potentially fade to light in a different manner. Hence, precisely and in-depth monitoring the potential color degradation to light was of great necessity. Therefore, the developed strategy in this work represents a constructive tool and provides the methods for relevant research on other color artifacts.