Glossary: How oil paintings age

As with everything in life, oil paintings age over the years and  become more mellow with a resulting lack of sharpness. This can be due to a number of factors which I will detail below

1. Dust, grime, soot and smoke. All these will be absorbed by the varnish on a painting or the paint if unvarnished. They can be cleaned off successfully but over the years they will affect the pigments of the paint altering the original colours fractionally.

2. Varnish. This is a resinous substance that will darken over the years changing the colours of the painting. Removing the old varnish and adding a new layer will restore most of the original colours. Be warned this is a job for a professional restorer.

3.Materials used in painting. From the moment it is finished there will be tiny changes to the surface and texture of the painting. Oil paint takes months or even years to dry completely and the drying process causes the texture of the paint to shrink leaving tiny gaps in the paint that attract dirt and alter the pictures appearance. The better the materials , the less this will happen. If the artist has added to much oil to his paint then the surface wrinkles and changes the nature of the picture. Also if the canvas or board (substrate) has not been properly prepared then the surface of the paint may crack. Now, a lot of what can occur only adds to the beauty of the picture and seldom detracts from an antique painting.

4.Pigments. Some pigments are very sensitive to ultra violet light and colour changes can occur over the years resulting in different tonal variations than those envisaged by the artist.

Nowadays, paints are much more stable and colour variations on new paintings are much less than 100 years ago when artists ground there own colours. We do, however, rely on artists to properly prepare there canvas or board to avoid excess cracking and lifting of paint.