Quite a few painters today don’t apply a coat of varnish to their work on completion. I have even spoken with a few painters who didn’t know that varnishing has been the traditional last step of the work of oil painting. Others wonder whether varnishing is useful. And then there is acrylic paint which behaves and displays differently from oil. So then, why varnish?
I can think of several reasons to varnish a painting. For one thing, this is the way that traditional paintings were finalized. If a more or less traditional appearance is desired, then varnish. Varnishing is also a way of getting rid of the contrasts between dull and glossy portions of a canvas and achieving a fairly uniform surface. Given the range of art varnish finishes, varnishing doesn’t necessarily mean the creation of a glossy surface on the painting. Matte varnishes are available. It is also true that a good varnish, particularly on an oil painting, will make the colors appear richer and more lively and even add to the sense of depth in a painting.
And then there is the issue of preservation. The traditional practice achieved the visual results just noted, but more importantly, it was intended to protect the surface of the painting. Dust and dirt can collect on the surface of a painting and even get embedded in the surface. A final varnish like Damar is re-dissolvable and can be removed with mineral spirits or turpentine without disturbing the oil paint layers below it, where the linseed oil that binds the pigment is no longer soluble. Remover the varnish and remove the dirt. Once cleaned, the painting can be re-varnished. All of this applies to acrylic painting as well. Acrylics themselves, like oils, do not re-dissolve, and this includes clear acrylic mediums used as varnishes, but there are final re-dissolving varnishes that can be used on acrylic paintings if desired.
Let me know what you think about varnishing.