Novel micron-thick brick cladding of polyfluorosilicone acrylates, a case study of conservation of historic brick wall in Hongcun village

A micron-thick (3–5 μm) and transparent cladding technique based on the environment friendly dimethyl carbonate solution of newly developed polyfluorosilicone acrylates was successfully applied to restore the surface of brick walls of a historic house which has been severely eroded by damp and mildew for more than 300 years in Hongcun village, one of the World Heritage sites in China. The restoration followed the rule of repairing old as old before. The cladding made from the copolymerized polyfluorosilicone acrylate resin, which mainly contained the chain fragments of dodecafluoroheptyl methacrylate and 3-(trimethoxysilyl)propyl methacrylate, permeated through the surface of old brick with an average depth of 14.5 mm in this case study, and provided an ultrathin and efficient covering of the microstructure of the shallow surface layer of old bricks and resulted excellent water-proof, moisture-proof, mildew-proof and long-lasting weather resistance effects. The water contact angle of the treated surface of the old bricks reached 133°, the water absorption of treated bricks was reduced from 16.1 wt% to 2.8 wt% after soaking in water for 24 h.