Whether to varnish an oil or acrylic painting is a matter of personal choice, with different arguments for and against. Varnish will add protection against moisture, UV light or smoke, and means the painting can also be cleaned without damage to the surface itself.
Varnish can also be removed and reapplied by a specialist if it has become compromised, providing an extra layer of protection for your painting. You can use varnish to even out the surface of work. Sometimes, depending on the primer, ground or paint used, patches of colour can ‘sink’ and appear as matt areas over the painting. Applying a retouching varnish can even out these areas and unify the surface throughout the painting, and can be applied between stages as the painting builds. A final varnish can then be applied to provide the painting with a consistent finish, ready to show.
Darker areas of shadow and paintwork can also be brought to life with a varnish, giving a rich luscious quality and prevent them looking flat and dull.