Restoration is a process that attempts to return cultural heritage to some previous state that the restorer imagines was the “original”. This was commonly done in the past.
Art conservation can involve the cleaning and stabilization of art work. Ideally, any process used is reversible, departures from that ideal not being undertaken lightly. Cleaning is not a reversible process and can sometimes be controversial due to fears that cleaning would damage a piece, or on the grounds that damage or residue forms part of the history of a given piece and should not be modified. Michelangelo’s statue of David has undergone two cleaning’s to remove dirt that had accumulated on the statue’s surface.
Art restoration is vital to the survival of classical paintings, photography and is part of the scientific application of chemistry. It often involves research to determine the original colors and materials of a work.