Analytical Characterization of the Leather Binding of a Precious 17th-Century Chaghatay Medical Manuscript from Xinjiang, China

Zhìliáo Zhǐnán (Treatment Guide) is a 17th-century Chaghatay medical manuscript included in China’s National Catalogue of Precious Ancient Books. Its leather binding is severely deteriorated, with extensive wear, blurred decorative patterns, fire damage, deformation, and multiple tears. In this study, colorimetry, near-infrared (NIR) spectroscopy, X-ray fluorescence (XRF) spectroscopy, extended depth-of-field microscopy, scanning electron microscopy (SEM), and proteomics were combined to characterize the cover, spine, back cover, and endpapers. Microscopic examination showed that the grain-surface pore pattern and cross-sectional fibrillar architecture were morphologically similar to modern goat leather; however, aging and surface loss prevent definitive species identification from morphology alone. SEM revealed pronounced collagen gelatinization in the cover. Proteomic analysis detected abundant type I collagen and identified casein-family peptides in the spine, supporting the use of a casein-based adhesive. NIR and XRF further distinguished leather from cellulose-based components and revealed marked spatial differences in elemental composition across the binding. Together, these results provide material evidence for the construction and deterioration of a 17th-century Chaghatay manuscript binding and establish an analytical basis for its conservation and restoration.