|Painting before cleaning.|
|Painting after cleaning.|
As a result, there are now several generations of artists who have never varnished a single one of their paintings. This omission could have dire consequences for their work. I'd like to direct your attention to the before and after images at the top of this post. This painting had been hung for decades in a room with a fireplace and has suffered substantial darkening as a result. Fortunately, the darkening occurred on the top layer--the varnish layer. It was a matter, then, of removing the varnish without disturbing the paint underneath and then revarnishing the work. In other respects the painting was stable; there was no peeling away of the paint layer. Had there been no varnish, there would have been very little that I could have done to clean the painting.
Varnishing is generally done six months after the completion of a work. If you are not certain whether a work is varnished try looking at it in a raking light. You ought to see a uniform layer of gloss. Even a matte varnish will have a certain uniformity of surface. If a painting displays some areas that are flat and some glossy, that is a clue that the painting may lack varnish. The shiny and matte areas would be the consequence of different amount of oil in the painting medium.
One artist that I know had an epiphany about the importance of varnish, but she could not bear to sit down and actually treat all of her paintings, so she came to me. I went through fifty or so of her paintings, of various sizes and various dates, and varnished them all. Being a conscientious person, she was also contacting buyers of her work and offering to varnish the paintings that she had sold to them.