Granular substance of notable strength, natural or artificial, used to smooth a surface by rubbing it. The most common abrasives are made from powdered glass, emery, quartz, carborundum, etc., then glued together to obtain a homogeneous surface on paper or canvas (sand paper and emery paper). Among the many applications of abrasives, they are used in the preparation of wood panels, canvases and many other supports for painting. In the restoration of paintings, the treatment of the old canvas with abrasives facilitates the lining.