ABSTRACT
Paintings do not look the same as when they left the artist’s studio. This is the result of drying and natural ageing processes that begin the moment the paint is applied and slowly progress over time, apart from changes caused by human interventions. Implicit in the ageing and deterioration of painted works of art are changes in the chemical, physical, and optical properties of the paint. Colours may fade or completely disappear; paint can become more transparent and yellow, and appear darker; and thin deposits can develop at the paint surface that can manifest in many ways. In the seventeenth century there was an awareness of the issue and concomitant increase in the number of methods of production of more durable colours and paints. From the fifteenth to the early twentieth century, artists primarily used oil binders, mostly linseed oil. Drying oils have the tendency to yellow over time.
