Growth regulation of calcium oxalate film for surface protection of carbonate stone heritage

The calcium oxalate film exhibits great potential for surface protection of carbonate stone heritage due to its excellent acid resistance and insolubility in water. However, the artificial calcium oxalate film is often loose in structure and weak in cohesion, resulting in limited protective performance. For the performance improvement of the film, glycerol was used as a growth regulator of calcium oxalate crystals, and the effect was investigated by SEM, EDS, IR, XRD, molecular dynamics simulation, Scotch tape test, acid attack resistance, water absorption, porosity, and color difference analyses. Results show the growth mode of the calcium oxalate film is altered due to the preferential adsorption of glycerol on the crystal surfaces of whewellite. Consequently, the calcium oxalate film becomes compact, cohesive, and crack-free, significantly improving the protective performance. This work is meaningful for the preparation and application of calcium oxalate film for the conservation of carbonate stone heritage.