Application of Gels in the Conservation of Chinese Ancient Calligraphy and Paintings.

Abstract

Chinese ancient calligraphy and paintings, as priceless cultural heritage, face dual conservation challenges: cleaning accumulated contaminants and combating microbial deterioration. Addressing these issues, this study develops a multifunctional poly(vinyl alcohol)/poly(2-hydroxyethyl acrylate) (PVA/PHEAA)-based hydrogel system, including a basic robust hydrogel, an ethylene glycol (EG)-modified antifreeze version, and a polyhexamethylene biguanide (PHMB)-composite antibacterial hydrogel. By tuning interfacial adhesion energy at the molecular level, these hydrogels enable gentle yet effective cleaning of delicate substrates such as Xuan paper, efficiently removing surface and embedded dirt without mechanical damage. Molecular dynamics simulations revealed a "capture-and-fixation" dual-mode mechanism driven by hydrogen bonding and network reconfiguration, supporting the experimental findings. The EG-modified hydrogel retains elasticity at -20 °C, allowing conservation work in cold environments. Meanwhile, the PHMB-integrated hydrogel achieves a 99.6% antibacterial rate against E. coli and S. aureus, combining cleaning and long-term antimicrobial protection. Quantitative cleaning tests (n = 3) showed the PVA/PHEAA gel removed >90% of particulates, significantly outperforming traditional methods while leaving no detectable residues. Experimental results confirm the hydrogels' compatibility with cultural materials and their multifunctionality in Xuan paper conservation. This study introduces a novel material solution for restoring traditional Chinese calligraphy and paintings, significantly advancing the application of functional hydrogels in cultural heritage preservation. By extending the lifespan of ancient artworks through a safe, residue-free, and reversible cleaning approach, it contributes to the enduring transmission of Chinese civilization.