Facile and Scalable Conservation of Chinese Ancient Paintings Using Water-Borne Fluoropolymer.

In China, alum-gelatin aqueous solution is historically used to prevent falling off of mineral pigments from paintings and to enhance strength of their paper matrices in the restoration process. However, after a long period of time of preservation, alum-gelatin aqueous solution applied to paintings will hydrolyze and produce free acid, which accelerates aging. To resolve this issue, instead of using alum-gelatin aqueous solution, here we report a new method of using a water-borne fluoropolymer coating to protect paintings. This coating is applied to simulated paintings, and their influences are systematically examined on the antipeeling property of pigment, mechanical properties, thermal stability, chromaticity, surface morphology, and water contact angle. Our results show that the applied coating slightly affects the appearance of the painting without falling off of pigment observed. Moreover, the coating increases the tensile strength and folding endurance of the paper because the polymer fills into the porous structure of paper fibers and covers pigment particles from SEM analysis. The treated painting retains moderate hydrophilicity, which facilitates removal of degradation substances from the paintings by water cleaning and the subsequent mounting procedure. Moreover, this coating is successfully applied to repairing a set of real ancient Chinese paintings of Yuan Dynasty (1271∼1368 A.D.), with practical acceptance. Our work provides a facile yet effective solution to conservation of ancient paintings by applying the modern fluoropolymers.