Simulated Aging Studies on Porcelain Restoration Adhesives for Conservation in Chinese Museums

The rapid development of archaeology in China has led to the excavation of numerous fragmented porcelain artifacts, for which adhesive materials play a critical role in conservation and restoration. The long-term stability of these adhesives directly affects the structural safety and visual integrity of restored objects. In this study, four adhesives widely used in Chinese conservation practice-epoxy resin Hezhong AAA, epoxy resin Hongxing 509, acrylic resin Paraloid B-72, and cyanoacrylate adhesive 502-were systematically investigated through simulated cyclic aging experiments. A multi-analytical approach was employed, including ultra-depth-of-field microscopy, CIE Lab* colorimetric analysis, pencil hardness testing, and Fourier transform infrared spectroscopy (FTIR). The results reveal distinct aging behaviors among different adhesive types. Epoxy resin adhesives exhibit high initial hardness and pronounced hardening during aging, with coating hardness increasing from the B range to the H range after 15 aging cycles; however, they also show significant yellowing, with total color differences (ΔE) exceeding 10 and dominated by increases in the b* parameter. Paraloid B-72 maintains excellent color stability throughout aging, with ΔE values consistently below 2, although it shows limited thermal stability and delayed physical stabilization. The cyanoacrylate adhesive 502 demonstrates rapid curing and minimal discoloration but undergoes embrittlement and interfacial debonding during aging, indicating reduced long-term bonding reliability. By correlating macroscopic performance evolution with molecular-level chemical changes, this study elucidates the aging mechanisms of commonly used restoration adhesives and provides a scientific basis for adhesive selection, risk assessment, and long-term preservation strategies in porcelain conservation.