Optimization of conditions for the cleaning of overpaint from the stone carvings of the Potala Palace, Tibet using enzyme-based cleaning agents

•Starting from the composition of the mortar on the surface of the stone carvings in the Potala Palace, we used enzyme-linked immunosorbent assay to determine the content of protein (as a binder) in the mortar to provide new ideas for the removal of mortar.•Taking corrosion rate and chromatic aberration as indexes, the best cleaning agent was selected from 9 different types of cleaning agents. This study is based on the existing cleaning technology to improve and innovate, and promote the development of biological protease cleaning technology.•Through single-factor test and response surface optimization test, this study obtained the best cleaning conditions for alkaline protease, and verified that the cleaning effect met the standard by measuring the surface roughness. This study fills the gap of traditional cleaning technology, which has high theoretical and practical significance to promote the development of the field of restoration and conservation of cultural relics.