Glossary

Photo-oxidation

Photo-oxidation reactions require oxygen (or ozone) and light and therefore often take place close to the surface of a painting, such as in a varnish layer. The generation of oxygenated species can often lead to reactions which result in this layer becoming discoloured and brittle. The incorporation of oxygen into the resin molecules of a surface varnish will increase their polarity and will alter the solubility of the layer.