Adding the right varnish, in the right way, is a sound investment to ensure your finished oil or acrylic painting stays looking its best. Varnish protects the painting from dirt and dust and evens out the painting’s final appearance, making it all equally glossy or matt.
Over the years, dirt and dust will stick to the varnish, rather than the painting. When the time is right, the varnish itself can be removed and the painting re-varnished to make it look as good as new.
Fixing dull paintings
If your painting is dull, it is easy to confuse the need for varnishing with the dullness created by the colour that has sunk into the surface. If the colour has sunk then varnishing should be avoided. Instead, you should “oil out” those sunken areas using Artists’ Painting Medium.
Sometimes artists varnish their work to help stabilise surfaces with added texture or damaged layers. But while varnish will certainly help with this, once the varnish is on it cannot be removed without damaging the work. If you have pictures like this, we recommend you keep the varnished work behind glass and think about how to improve your technique for the future.
What types of finished surfaces can be varnished?
Varnishes work well with oil and acrylic because the paint films are relatively thick and separate from the surface.
Varnishes do not work well with gouache, watercolour and drawings, because they will be absorbed by the paint and/or paper, becoming an integral part of the picture. This could cause discolouration. Additionally, varnish on drawings and gouache or watercolour works cannot be removed.
Generally, artists choose varnishes for the sheen they provide, or because they have been used by their favourite painters. Here’s a brief overview of the different kinds of varnishes:
Dammar remains one of the most popular varnishes, even though newer ones have been introduced since its development.
Gloss varnishes are chosen because they give the brightest, deepest colours. But works with gloss varnish have a lot of reflection.
Matt varnishes avoid reflections but the colours appear duller.
All Winsor & Newton varnishes can be used on oil, alkyd, water mixable oil or acrylic paintings. But all are designed with specific types of colour in mind.