Infrared thermographic evaluation of cleaning stone relics at tomb of Yue Fei

This study investigates the efficacy and safety of steam cleaning technology for the removal of surface contaminants from stone cultural relics at the Tomb of Yue Fei, a nationally protected heritage site in China. The research focuses on common pollutants including dust accumulation, surface encrustation, hydro erosion, bioerosion, and anthropogenic graffiti. An evaluation method based on infrared thermography is proposed to assess cleaning effectiveness by analyzing temperature variation (T) before and after treatment. Field experiments were conducted using a steam cleaner with controlled parameters (pressure, temperature, angle, distance, and duration), and cleaning outcomes were evaluated through visual inspection, chromatic aberration measurement, and microscopic imaging. Results demonstrate that steam cleaning effectively removes most contaminants without causing significant damage to the stone substrate. The study also provides a set of recommended steam cleaning parameters for different pollutant types on limestone surfaces. The findings validate the feasibility of using infrared thermography as a non-destructive evaluation tool for cleaning efficacy, contributing to the development of standardized protocols for the conservation of stone heritage.