Aging is a process by which an artwork, typically a

painting Painting is the practice of applying paint, pigment, color or other medium to a solid surface (called the "matrix" or "support"). The medium is commonly applied to the base with a brush, but other implements, such as knives, sponges, and a ...

sculpture Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable ...

, is made to appear old. It is meant to emulate the natural deterioration that can occur over many decades or centuries. Although there may be "innocent" reasons for it, ageing is a technique very often used in art forgery. Paintings deteriorate over time because they are created using essentially incompatible materials, with each having a different reaction to the changes in the environment, including light, temperature and

relative humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity dep ...

. An oil painting consists of several layers, comprising the base

canvas Canvas is an extremely durable plain-woven fabric used for making sails, tents, marquees, backpacks, shelters, as a support for oil painting and for other items for which sturdiness is required, as well as in such fashion objects as handbag ...

, a layer of

gesso Gesso (; "chalk", from the la, gypsum, from el, γύψος) is a white paint mixture consisting of a binder mixed with chalk, gypsum, pigment, or any combination of these. It is used in painting as a preparation for any number of substrates suc ...

base coat, several layers of the oil-based paint and then several coats of

varnish Varnish is a clear transparent hard protective coating or film. It is not a stain. It usually has a yellowish shade from the manufacturing process and materials used, but it may also be pigmented as desired, and is sold commercially in variou ...

to protect the paint surface. With many different materials, it is understandable that each layer may dry at different rates and will also absorb and release moisture at different rates. When this occurs, expansion and contraction of the painting will result in a crazing of the varnish surface. This pattern of small cracks is known as

craquelure Craquelure (french: craquelé; it, crettatura) is a fine pattern of dense cracking formed on the surface of materials. It can be a result of drying, aging, intentional patterning, or a combination of all three. The term is most often used to ref ...

. Along with the darkening or yellowing of the varnish surface, it is this visual representation of the cracking that is typically the primary indicator of ageing. The purpose for artificially ageing is to create a finished product that accurately reflects an era or is consistent with the environment (usually period) into which it is to be placed.

See also