Varnishing Oil Paintings

When an oil painting is finished and completely dry, it will need a layer or two of varnish.

Varnishing is necessary because it provides a protective layer between your painting and damage from scratches and handling as well as dirt and pollution in the environment. A varnished painting will also have the added benefits of saturates colors and a unified finish, or sheen.

The general rule is to wait 6 months after completion before varnishing though some paintings will dry sooner and some take longer - more nuance is discussed here.

Natural Resins vs Synthetic Resins

In the past, natural resins derived from tree sap, such as Damar and Mastic, were dissolved in solvents like Turpentine to create varnish for paintings.

However, in art preservation today, synthetic resins such as Regalrez 1094 (a synthetic hydrocarbon resin) are generally preferred because they are more chemically stable than natural resins and have consistent solubility, which better protects paintings from yellowing, cracking, and environmental damage.

Strong solvents like acetone are required to remove old and oxidized varnishes made from natural resins, which can harm the painting underneath, whereas gentler solvents that do not harm the painting, such as odorless mineral spirits, can be used to remove synthetic resins.

High Molecular Weight (HMW) synthetic resins like Paraloid B-44 tend to produce a more matte to satin sheen while Low Molecular Weight (LMW) synthetic resins like Regalrez (used in Gamvar varnishes) and Laropal A81 tend to produce a more satin to high gloss sheen.

Matting agents such as beeswax and silicone dioxide (aka silica) may also be added to synthetic resins to reduce gloss, as is the case with Gamvar Satin and Gamvar Matte varnishes.

Gloss vs Satin vs Matte Varnish

The video below compares Gamvar Matte, Satin, and Gloss varnishes:

Gloss varnish is often preferred for dark-color paintings because it saturates them. The downside of gloss varnish is that it’s shiny and reflected light can obscure details depending on the angle that a painting is being viewed.

Matte varnish does not reflect light but can also dull colors. Some artists prefer a matte finish for paintings with lighter colors.

Satin varnish is semi-glossy and saturates color, but not as well as gloss varnish. Satin varnish reflects some light, but not as much light as gloss varnish.

Gamvar varnishes are suitable for both acrylic and oil paintings and do not contain UV stabilizers. If you are painting with lightfast pigments, UV light is less of a concern (see my preferred pigments list here - every pigment listed has a lightfastness rating of I).

You can learn more and purchase Gamvar varnishes here.

How to Apply Varnish to Oil Paintings

Gamblin’s varnish brush is available here.

When applying varnish to your painting, the wrong way to do it is to pour it directly onto your painting like syrup and then spread it around (unfortunately, this has become a trend on social media!).

This might look cool but conservators caution against this method because getting a thin and even coat is difficult.

What’s the correct way to varnish a painting?

First, make sure your painting is dry, clean, and free of dust. Wipe off any dust or hairs with a lint-free cloth.

Wiping dust off of an oil painting in preparation for oil painting.

Next, lay your painting flat and apply a thin and even layer of varnish. The easiest way to accomplish this is by pouring a small amount of varnish into a bowl and using a wide flat brush to apply strokes of varnish on your painting. Be sure to shake the bottle of varnish well - especially if using a matte or satin varnish - before pouring it into the bowl. Vertical strokes are recommended because they are less likely to catch the light than horizontal strokes. You can also use a sprayer or spray varnish to get an even varnish layer.

Artist Nikita Coulombe demonstrates varnishing a painting in vertical strokes.

Then, tilt your painting at an angle so the light catches it. This way you can see if you missed any areas (missed areas will appear matte).

Freshly applied varnish is tested against the light to reveal any missed spots, which will appear matte.

If there is excess varnish, remove it by feathering your brush and wiping the brush on paper towels.

To prevent dust from sticking to your painting while it’s drying, you can put a piece of cardboard over it or in front of it, or tilt it against a wall - be sure to leave an inch or two of space to allow for airflow.

How Many Coats of Varnish Does a Painting Need?

Gamblin states that one coat of Gamvar offers excellent protection for paintings. If you want an even higher gloss or pronounced sheen, you may add another coat after 24 hours.

Matte vs Satin vs Gloss varnish comparison.

From left to right, the first row in the image above shows a single layer of matte, matte and satin, satin, satin and gloss, and gloss varnish. The second row shows two layers of those varnishes. Notice how the second layer is glossier regardless of whether the varnish is matte, satin, or gloss.

Cleaning Your Varnish Brush

Brushes can be cleaned with odorless mineral spirits (Gamsol) then soap and water. The best method I’ve found is to put a small amount of Gamsol in the same dish that I used for the Gamvar, let the brush soak for a minute, press the brush into a paper towel, and then let it soak again for another minute and let the paper towel absorb any remaining liquid. If the brush dries a little tacky, this process can be repeated and then washed with soap and water.

How to Remove Varnish From Oil Paintings

Gamblin's Gamsol odorless mineral spirits.

Gamvar is easily removable.

If for some reason you do not like how your varnish turned out, you can safely remove it by following the instructions below, which have been taken directly from Gamblin:

Take a clean lint-free cotton cloth and wet a corner with Gamsol.
Using circular strokes, dissolve a small area of the varnish at a time.
Immediately wipe away the dissolved Gamvar with another dry cotton cloth.
Repeat until the varnish is removed from the desired areas. Usually, there is enough of a difference in surface sheen to tell where Gamvar has been removed.
A final wipe-down with a fresh cloth and Gamsol may help to ensure any residual varnish is completely removed. Allow Gamsol to evaporate completely before continuing to paint.

You can learn more and purchase Gamsol here.

Note that Gamvar varnish should be removed before adding any new paint. You do not want varnish between layers of paint because it may increase the paint’s brittleness and cause delamination.

Notes on Varnishing Acrylic Paintings

Acrylic paintings may also be varnished with Gamvar.

However, Golden makes a water-based acrylic varnish specifically for acrylic paint called Golden Waterborne Varnish.

This liquid varnish has a glossy finish and is formulated with UV light stabilizers, which offer a layer of protection against sunlight exposure. Golden's Waterborne Varnish also protects acrylic paintings from dirt, dust, and scratches. The varnish can be thinned with water instead of odorless mineral spirits and is applied to the painting surface the same way that Gamvar is.

Unlike with oil paintings, you do not have to wait 6 months to varnish an acrylic painting. Golden states that if a finished painting is composed of thin layers of acrylic paint or other water-based media, you only have to wait a couple of days before applying the isolation coat or isolation layer of varnish ("isolation" just means you are isolating the painting with the varnish). You can then apply a second coat, also called a finishing layer, of varnish after the first layer of varnish dries ("finishing" means the top layer of varnish) after a couple of days.

Like Gamvar, this is a removable varnish. Golden outlines the varnish removal process here.

Golden Gloss Waterborne Varnish for acrylic paintings.

You can learn more and purchase Golden Waterborne Varnish for acrylic painting here.

Nikita Coulombe Fine Art