Is Varnishing Necessary?

Only the artist can say what’s right for their art, but there are important practical and aesthetic reasons behind the choice to varnish or not. Even though there are instances when paintings can or should be left without a top coating, most of the time applying varnish to a finished painting is a recommended practice because it protects paintings and enhances artwork appearance.

What is varnish?

Varnish is a clear coating that protects materials underneath and imparts a uniform finish. When we talk about varnish today, we’re almost always referring to a “solution varnish” which consists of a resin in a hydrocarbon solvent, ketone, or sometimes alcohol. Some types of varnish that we still use today were used by historical artists, but there were others that are no longer in common use, like oil varnishes. These were made by cooking fossilized resins into oil under very high temperatures. These heavy coatings were abandoned because they were extremely dangerous to make, darkened with age, and couldn’t be removed once dry.

One natural varnish that’s still in use is Damar, made from a sustainably cultivated resin. You can even make it yourself in the studio, if you’re able to use turpentine. Damar is included in many traditional painting mediums, and it produces a beautiful finish that looks like a shiny candy coating. But because damar requires turpentine and gets harder to remove as it ages, many artists use synthetic varnishes instead. Synthetic varnishes offer the benefits of traditional products, but they keep their flexibility and neutral color, and stay reversible in the long term.

Protection:

Paintings pick up dust and grime like all surfaces, but paint can be delicate and porous, so a lot of what lands on them can become embedded. That can make it challenging and risky to dust or clean them. Varnish acts as a barrier over the paint, making the surface safer to dust and easier for professionals to clean. Varnish also protects against accidental, casual contact that could damage a delicate surface.

Varnish enhances paint appearance by bringing out depth and richness in colors that might otherwise look uneven and dull. Both sprays and liquids can give great results. With a brush-on varnish, you can apply a heavier coat, but sprays help avoid brush marks and drips. Most types give a gloss finish, but if shiny surfaces aren’t to your taste, or glare is a problem, matte or satin-finish varnishes are a good option.

Image (left): Example of artwork showing depth of color in a varnished painting: John Everett Millais – Ophelia (c. 1851–1852), oil on canvas.

Permanent vs. Temporary

Even though varnish is applied directly to paint, it’s not normally considered a permanent part of the picture. It’s made to be removable if necessary, like the glass in a frame, in case the painting needs to be cleaned or repaired in the future.

Some clear coatings applied to art are not removable, however, like pourable polyester/epoxy clear coats, and clear acrylic medium applied as a last layer over a painting. These are different from standard picture varnish, and they are a permanent part of the artwork. Resin is not a standard picture varnish, and may not always work for every picture. Paintings on rigid panels are much more capable of bearing the weight of heavy, poured clear coats, which could crack on canvas. It’s also important to determine whether paint will interact with the clear resin or suffer any destructive effects, since any deterioration or defects in paint will be locked in permanently.

Some artists apply clear acrylic medium over finished acrylic paintings, followed by a standard picture varnish, to isolate the paint and reduce the chance of damage during future cleanings.

Image (right): Portrait by Claude Monet undergoing varnish removal (under UV light at right)

What kind of painting can be varnished?

Oil and acrylic paintings can both benefit from being varnished, and you can usually use the same products on either type of painting. Acrylics can be coated as soon as they’re completely dry, but oils need up to six months before getting a final varnish. Artists from the Renaissance into the 19th century would sometimes make paintings too fresh for varnish look shiny by applying “glair”, a diluted egg white mixture. It’s a lot simpler today to use retouch varnish, a light coating that protects and evens out shiny and dull spots while letting paint cure.

When Not to Varnish

Mixed-media pieces may include materials that can’t accept varnish, and watercolor and gouache can be permanently altered by varnish. In these cases, you can frame under glass, or pick a display location that’s relatively free of dust and contaminants and rotate it with other art to limit the display duration.

There are also times when varnishing might seriously change the artwork appearance, or conflict with the artist’s intention. If you don’t like the way varnish looks on your art, if that’s not how you want your paintings to be seen, then varnishing isn’t the right call. Preservation means maintaining art the way the artist intended, and any treatment that changes that isn’t serving the purpose.

Image (right): Example of painting that was not varnished: Still Life by Georges Braque, 1926, oil on canvas.