Glazing and varnishing in art restoration

Congratulations to Bill Valerio on another informative article for The Chestnut Hill Local about the happenings at Woodmere Art Museum [“One painting takes a road trip...” October 30]. I don’t know how he finds the time, but I’m sure the local community loves reading them as much as I do.

In last week’s article, Bill and I discussed William Trost Richards’ On the Cornish Coast, a painting in Woodmere’s collection that’s currently on view. I spoke with Bill after the article appeared and we want to take this opportunity to clarify some of the wording that we used, and make the distinction between the terms “varnish” and “glaze.”

Glazing: The word glaze is used by art historians and paintings conservators to describe a semi-transparent, pigmented layer applied by an artist to add depth and color to a painting. Artist’s glazes, it should be stressed, are not removed by conservators.

When we were examining “On the Cornish Coast” I may have referred to some of the repaint in the sky as “restorer’s glazing,” and if so, I apologize. In the past, restorers on occasion used a “glaze” of thin repaint (often pigments in varnish) to hide abrasions (partial removal of the original paint surface) to the paint layer. To correct this, conservators will usually remove the former restorer’s repaint glazing because this glazing often covers intact, original paint.

The conservator will then do proper inpainting confined to the abrasions and then, if necessary, apply our own reversible pigmented “glaze” to an area where former, non-reversible glazes had been partially removed. It was necessary, for example, for the conservators at the Philadelphia Museum of Art to do this on a number of paintings by Thomas Eakins because the artist’s original glazes had been partially removed or damaged during previous attempts at restoration.

Some restorers of the mid-20th century were, apparently, subconsciously applying their visual preferences for the bright colors in Impressionist paintings to Eakin’s paintings. They went to great lengths to try to remove what they thought were discolored varnish layers when were, in fact, artist’s glazing layers, in order to brighten the paintings. Today microscopic examination, solvent testing, and a familiarity with the artist’s working methods help us to avoid removal of glazing layers that are meant to be a part of the paining.

We want it to be clear that when any painting is conserved for Woodmere, we will only be removing discolored varnish, grime, and restorer’s repaints. We will not be removing any artist’s glazing.

Varnishing: A varnish is a finishing coating, initially virtually clear, that is applied by the artist, or his agent, one year after the painting has been completed. This layer is applied only when there is a desire to saturate the colors, and possibly to protect the paint layer from absorbing grime. (Not all artist’s varnish their paintings.) A varnish is usually considered to be a removable/reducible component because a natural resin varnish will turn yellow-brown, lose its saturating ability with age, and accumulate grime, thus altering the intended appearance of the painting.

It’s not uncommon for yellowed varnish and grime to be mistaken by a viewer for a pigmented glaze, and when present-day conservators remove or reduce a yellowed varnish they are sometimes accused of having removed an artist’s glaze.

People may find a change in something they loved just the way it was difficult to accept. Rembrandt’s “The Mill,” for example, was cleaned of its multiple layers of brown varnish about 35 years ago by conservators at the National Gallery, in consultation with renowned art historian Arthur Wheelock.

The un-cleaned painting had centuries of varnish on it and had acquired a golden glow; it looked like a dark sunset, murky and mysterious. It was lovely and romantic and had even inspired some late 19th century painters in its dirty state. But it was not what Rembrandt had painted. There is, in fact, at least one 18th century copy of “The Mill” that shows it as having a blue sky.

Now that the original has been cleaned of those layers of grime and discolored varnish, it indeed does have a blue sky. But when the cleaned painting was put back on display, people who loved the romantic darkened appearance accused the conservators of having removed some of Rembrandt’s pigmented glazes.

They had not. The cleaning was carried out after a thorough technical examination and with input from one of the most respected scholars of 17th century Dutch art. The painting is quite well preserved and almost everyone now appreciates its current, extraordinary appearance.

Today the conservation of paintings has become a delicate, thoughtful process where conservators and curators strive to clarify the artist’s vision so that their message, whether light or dark (metaphorically and factually), can be appreciated and seen by all.

Enjoy and experience some of those messages at Woodmere!