Preparation of Copper-Loaded Zeolite/Nanomaterial-Modified Raw Lacquers and Their Application as Potential Topcoats for Guqin Soundboards

The guqin is a traditional Chinese musical instrument with a long history, and lacquering is a key step in modern guqin fabrication. Nevertheless, traditional raw-lacquer coatings on guqin soundboards possess poor wear and weathering resistance. During frequent use and varied storage conditions or in certain environments, these coatings are susceptible to bacterial contamination, as well as photothermally induced embrittlement and aging. In this study, while retaining the essential features of the traditional lacquering process, candidate modified raw-lacquer topcoats with potential for application to modern guqin soundboards were prepared. Natural raw lacquer was used as the matrix, methyltrimethoxysilane (MTMS) as the crosslinking agent, copper-loaded zeolite (Cu(II)-nZ) as the antibacterial agent, and boron nitride (BN) nanosheets together with nano-ZnO as functional modifiers. The modified lacquer coatings showed improved antibacterial property, wear resistance, interfacial adhesion, and UV aging resistance. Although Cu(II)-nZ addition was accompanied by a decrease in surface gloss, the resulting lower-gloss appearance may be compatible with the subdued visual character of traditional guqin finishes. The modified raw-lacquer coatings also showed low hemolysis in vitro. Collectively, compared with conventional raw lacquer, the modified raw-lacquer coatings exhibit improved material-level protective performance. They are worthy of further investigation as potential topcoats for guqin soundboards, with acoustic and vibrational validation to be performed.