Paintings age for a variety of reasons, such as exposure to high temperatures, humidity and light. Ageing is mainly caused by changes in the chemical and structural compositions of pigments in the paint as they gradually interact with each other and their environment over time. Now, Boris Zilbergleyt of the Systems Dynamics Research Foundation in Chicago has developed a new dating technique that simulates these interactions (

Zilbergleyt analyses how various commonly used pigments, such as "yellow cadmium" (which contains cadmium sulphide) and "lead white" (lead carbonate), react with each other at room temperature and pressure. Typical pollutants such as carbon dioxide and hydrogen sulphide are also included in the simulations. According to Zilbergleyt, the results of the simulations agree well with colour changes observed in real paintings as they age.

"My method successfully predicts the chemical ageing of paintings and could therefore be used to relate a painting to a certain time or place -- or even to a particular painting school," Zilbergleyt told PhysicsWeb. "In some cases this could be a way to tell between real works of art and fakes that have been artificially aged -- like the famous Han van Meegeren forgeries, for instance." Zilbergleyt says he would now like to create special simulation software with its own specific database for art professionals.