Artists have used varnishes to coat their paintings since the 1400s—some claim as early as the eleventh century. Varnishes serve to saturate the paint colors, provide some degree of protection for the paint surface, and to impart an even surface sheen. Some artists have used varnishes as an aesthetic medium, mixing resins into wet paint to create rich translucency or selectively applying them to juxtapose areas of matte and gloss.
Conservation & Varnish
In modern conservation practice, varnishes are used as barriers between the original surface and restoration materials and often applied atop a treated painting to visually blend restored areas with the original surface.
Natural (tree) resin-based coatings have been the most prevalent, traditional varnish material but turn yellow and brittle with age. In extreme cases, coatings have darkened or degraded so significantly as to completely obscure the painting beneath.
Today’s artists and conservators may also choose from synthetic resins with specific characteristics to control coverage, sheen, and aging properties. These newer varnishes are meant to age better than natural resins but tend to turn grayish or have a “plastic” appearance over time.
Varnish Layers on The Virgin of Valvanera
Prior to current conservation treatment, The Virgin of Valvanera had several varnish layers on its surface, some no doubt applied by past restorers and conservators after removing previous coatings. There are three main varnish layers present: an old mixture of natural resin and oil directly atop the paint surfaced (darkened to an amber color and pooled in the “valleys” of the paint texture), a modern polymer layer of high molecular weight applied selectively to keep “dry”-looking dark passages saturated, and a layer of low-molecular-weight polymer applied most recently to unify the surface sheen overall. Sandwiched between these varnish layers are several years of grime, restoration materials covering successive damages, cotton fibers from previous cleanings, and selectively applied coatings such as wax.
The Virgin of Valvanera is remarkably lacking in structural problems for something of its age—there are no tears, significant damages to the canvas, or linings applied by previous restorers—but the numerous, well-intentioned campaigns to “improve” the painting have gradually masked the original colors and contours of the paint surface.
Making the Original Surface Visible Again
Imagine the face of a person whose habit is to apply makeup without completely removing previous layers except in small, select areas. After a long period of time, this face would become obscured and unnatural in appearance. Slow, methodical cleaning would reveal the skin beneath, undoubtedly marked with natural age, damages, and intrinsic flaws. Like this face, this painting, once cleaned, will receive an overall thin, protective layer and individual problems will be “spot-treated” so that as much of the original surface is visible once again.