Disodium EDTA has often been mentioned in relation to the removal of Crusts and for general cleaning of stone including marble. Recent research undertaken by Artcare through a grant from the Australian Institute of Aboriginal and Torres Strait Islander Studies (AIATSIS) has shown that although EDTA dissolves gypsum it has a more pronounced effect on other constituents of the stone. The current research has assessed the impact of various treatments on sandstone commonly found as the support for Aboriginal rock paintings together with crusts and pigments typically present on the surface of the stone. -- CAL