Reversing the effects of ageing and damage on a painting is a delicate process that uses a variety of techniques.
First, a cleaning solution is applied to remove dirt and deposits. Then the restorer identifies previous retouches, shown up under ultraviolet or infrared light, before carefully stripping away discoloured varnish and retouches.
Any damage to the canvas or support structure is repaired. Mixed with a binder to form a putty, pigments are applied to areas where paint has been lost.
These retouches may be removed with solvents that will not damage the original painting, meaning any changes can be reversed.