Inorganic patinas are part of the rock art now. The removal must stop when the original is threatened. The same criteria to any art piece. Rock retouching, of residues of insect galleries and other superficial deposits or losses, is useful to have a better view. But this direct intervention is important facing a tourist exploration.
Biological deterioration is faster than weathering.
It is better to avoid the growth than to remove roots and patinas. Sometimes it is difficult to keep the situation without using biocides. Decisions must be taken considering the emergency. Border of Cosmos cave with drip line to avoid percolation over a winter solstice painting I thank the professionals who helped me with information and scientific analysis. I emphasize the necessity of a basic working team with an archaeologist, a geologist, a biologist, a chemist, a photographer and a computer designer, to have a documentation of the state of conservation and reasonable conclusions about performed tests.