Subtraction is the act of removing. In art, an action is subtractive when it produces subtraction, as of some materials in carving, for example. Materials especially appropriate for subtractive sculpture in schools include clay, chalk, plaster, soft salt blocks, artificial sandstone, soap, and wax. The mixing of pigments is also called subtractive color mixing (as opposed to the additive mixing of incident light to achieve additive color mixing). The subtractive primary colors are cyan, yellow, and magenta.Also see angle of incidence, assemblage sculpture, blot, construction, dent, detritus, erasure, light, manipulate, modeling, primary colors, secondary colors, and solvent.