The clean and evaluation methods for the paint pollution on the surface of masonry relics

The immovable cultural relics such as masonry relics, sometimes become targets of vandalism due to their long-term exposure to the outdoors and difficult to regulate. Therefore, it is very important to study an effective treatment method after these accidents. In this work, 3 types of organic solvents were evaluated for their efficacy in cleaning three common types of paint. Through the paint film softening effect assessment, cleaning pressure selection, paint removal rate calculation, andcleaning safety evaluation, a systematic evaluation of the cleaning effect was carried out. The results showed that the paint cured for 24 h was applied with a cleaning agent primarily composed of methyl-carbonate to soften paint, followed by rinsing with water pressure at 0.1MPa. After repeated cleaning, the paint removal rate could reach up to 97 %, with the rock surface damage was less than 1.5% (invisible to the naked eye). For the paint cured for 72 h, a cleaning agent mainly consisting of dichloromethane was used, which provided better cleaning effects and higher safety for the cultural relics themselves.