[78] Bone white coatings were confirmed to be present in the silver/goldpoint drawings by Jan van Eyck, and in metal point drawings by Albrecht Dürer. Its abrasiveness was the precondition for drawing lines. See Wallert et al., 2016, “Notes on the Material Aspects (Metal Point),” p. 25–35, and Reiche et al., 2001, “Non-Destructive Investigation of Dürer’s Silver Point Drawings by SyXRF”.