Within the field of icon painting, levkas is the mixture of fine alabaster powder, calcium sulfate, or calcium carbonate (chalk) along with glue applied in layers to a surface prior to gilding that surface with gold leaf or painting it, similar to gesso. The levkas is a bright white color which allows the colors of the paint to appear their brightest. As many as six to seven layers may be applied in preparation for the painting of a religious icon. A painting or icon whose surface has been damaged may have lost some of its layers of levkas.