To Varnish or Not to Varnish – That Is the Question

To Varnish or Not to Varnish – That Is the Question

Varnish is a specialized protective coating designed to safeguard oil paintings and works created in various other techniques.

Hardly anyone would consider displaying a watercolor artwork at home without securing it safely behind protective glass. Yet, when it comes to oil paintings, many art owners surprisingly hesitate or fear applying a protective coating to them.

Even the renowned American artist Georgia O'Keeffe was eventually forced to contact museums holding her oil paintings. Her works featured a distinctive, velvety matte texture created by using very dry pigments with minimal oil binder—and, naturally, no varnish. Ultimately, she had to instruct the institutions to coat them with varnish because the paint layers had simply begun to crumble and deteriorate over time.

The Golden Rule of Varnishing

When it comes to varnish, the adage "the more, the merrier" definitely does not apply. The protective layer must be thin and even. If applied too thickly, surface tension builds across the canvas, actually accelerating the natural cracking rate of both the paint and the varnish itself.

Varnish is not meant to be permanent and must be renewed periodically. The general consensus among conservators is that after 10 to 30 years, a painting should be entrusted to a skilled conservator. The specialist will safely remove the old varnish layer—which, over time, has absorbed pollutants, darkened, yellowed, and cracked—and apply a fresh protective coat.

This timeframe varies widely (10 to 30 years) because several external factors affect the rate of aging, including:

Air pollution levels in the environment
Exposure to ultraviolet (UV) radiation
Cleaning habits and maintenance practices

Restoring the Artist's Original Vision

A fundamental ethical principle of art conservation and restoration is returning the artwork as close as possible to its original state—exactly how it looked when completed by the artist.

This is precisely what professional cleaning and proper varnishing achieve. When an artist finishes a painting, the colors are rich, saturated, and vibrant. Over the years, however, colors tend to dull, cloud, yellow, and darken significantly. A careful yet thorough cleaning, followed by an appropriate protective coat, effectively turns back the clock while significantly slowing down future decay.

When Is an Oil Painting Ready for Its First Varnish?

The ideal timing for applying the initial coat of varnish to a new oil painting is 6 to 12 months after completion, depending on the thickness and number of paint layers.

A Useful Tip: Another simple way to check if a painting is ready is by scent. Once the characteristic smell of linseed oil has largely faded, it's time to varnish!

By Michael Karo

First published in "Auction" Monthly Magazine, Issue No. 21. Expanded and updated April 2014.