The Uses of Varnish

Painting conservator Susan Blakney examines an oil painting
by Art Price.

I love it when conservation information is included at art museum exhibits.  Typically, you see a vibrant and beautiful image on the canvas and then to the right is a digital image that shows how dark the painting looked before treatment.  The label explains how the conservator painstakingly removed layer after layer of varnish to find the original colors hiding beneath.

And I’ve wondered:  Why’d people put on all that varnish in the first place?

Susan Blakney with an oil painting
by Art Price.

Well, first of all, it protects the painting.  Susan Blakney, painting conservator and owner of West Lake Conservators, carefully examined my father’s paintings to determine his approach to varnishing.  The first painting, the landscape of Noyac, showed no sign of varnish.  “Varnish would have helped,” she said.  “It would have provided a layer to protect the paint layer from grime.  Then when you remove the grime it would not have penetrated the paint. Grime is one of the many enemies that a painting conservator confronts on a daily basis.  And lots of grime can accumulate on a painting over the years.  It firmly attaches to some paint layers making cleaning very difficult to remove without specific formulations developed through a sequence of testing.”  As Susan asked me, “Can you imagine a window in a home that hasn’t been cleaned in 60 years?  Well, that’s the amount of grime on this painting.”

Apparently, all that darkening on varnished paintings that I noted at the beginning isn’t entirely the effect of the aging varnish.  It’s the grime, too.  “Paintings can lose the illusion of depth perspective because of grime,” Susan said.  “With cleaning, the lights get lighter and the darks get darker.  A disfigured painting for whatever reason alters our perception of its beauty and the artist’s talent.”

Susan noted that you can’t safely form an opinion on an artist’s use of varnish by looking at just one painting.  Sure enough, the second painting she looked at suggested that my father may have used a different artistic approach on this one (a harvest scene).  “Artists have all different opinions about varnish.  Some cover all their paintings, some never use it, and some use varnish in selective areas but not others.”  This second painting looked like it might fall into that third category – partially varnished.  Furthermore, some artists  may have different approaches according to the subject or the medium of the particular painting.

Susan Blakney examines an oil painting
of a harvest scene by Art Price.

Since Susan was conducting this examination in a hotel conference room, she lacked the equipment to firmly identify the presence of varnish on the second painting.  Conservators normally use ultraviolet light to detect varnish.  According to Susan, “If the painting fluoresces cloudy in ultraviolet light, it’s a sign of varnish or possibly an intentional glaze – perhaps a varnish-like medium with or without the addition of a clear pigment to deepen a passage or color.”

Conservators often use varnish as an isolating layer or base for their in-painting of losses.  Stable synthetic varnish makes an ideal base layer for this work because it can be easily removed at a later date without damage to the original painting beneath.  This is important because one of the cardinal rules of art conservation is to ensure that all materials used in treatments are reversible.  Varnish is sometimes applied by the artist himself or someone in a maintenance situation after a painting has hung for some time collecting a grime layer. The older the painting the more likely it is that there will be multiple layers of grime and varnish.  In order to freshen a painting’s appearance, an owner may even apply the varnish improperly while the painting is still in the frame, potentially leaving the painting firmly stuck to the frame.  The end result can be layer upon layer of varnish alternating with grime – and a painting that looks decidedly murkier than when it was originally painted.

Painting conservators who examine these layers of varnish and grime must determine the layer structure and decide which they want to remove.  Different resins with different solubility parameters may have been used. According to Susan, “We don’t usually attempt to remove grime and varnish at once although at times it is possible and desired.  We often use different formulations for each layer. Cleaning may be the most irreversible and dangerous part of the treatment if done improperly.  Unfortunately, the paint can be dissolved and/or abraded, which we call skimming. Some commercially available cleaning solutions can leave a very unevenly cleaned surface which is one of the most difficult tasks a conservator can encounter.  There is also the risk that glazes can be stripped off.  I never recommend that owners attempt to clean the paintings themselves. It took me years to develop the necessary skills.”

© 2011 Lee Price