A general term used to describe the removal of a substance from a substrate. Substances removed in cleaning may include mud, dirt, grease, stains or previously applied adhesive, coating or compensation. In paintings conservation “cleaning” usually refers to varnish removal, often with solvents, whereas “surface cleaning” means the removal of dirt, grime, tobacco smoke residue, etc. usually with dry or aqueous methods.

Sounce: Dommermuth, Jean. Glossary for Principles of Conservation course, Conservation Center, Institute of Fine Arts, New York University, 2012.