All paintings need care and should be maintained. In analysis, a painting is nothing more than common materials put together in an uncommon fashion. As the art of painting developed so did the chemistry of materials and the value of learning by apprenticeship. History has recorded many of these practices, the changes in the materials used as well as what was painted (i.e., the support) walls, panels, canvases, ivory, etc., and the quality of pigments and combinations of oils, dryers and thinners.
An apprentice to a master painter learned how to construct a lasting painting as well as how to fashion its color and composition. Apprenticeships are rare today and the artist may have to look to a variety of resources to find the information necessary to understand materials and supports. Paintings done by an artist who has learned how to choose and combine materials will construct a more lasting work of art.
Since many artists and conservators were and still are very secretive about their craft, (i.e., material composition and techniques of application) experience is one of the most important ingredients for the creation of a successful painting or its conservation and/or restoration.
Artwork created by amateurs and artists experimenting with either material combination or techniques (i.e., mixed media) can be fragile and short-lived. For a painting to be successfully conserved or restored it must have been created with a reasonable support and with some integrity of materials. Some artwork cannot be fixed either by reason of the original composition of materials, the manner of application, or the type of abuse and current condition.