How to Varnish a Canvas Art


Varnishing a canvas art may be a confusing subject among artists. Varnish serves as a protection of your painting from pollution, scratches, UV rays, and other contaminants. It also brings out the colors and brilliance of your painting.

In oil painting, varnish gives the painting the same gloss level and it protects the piece from dust and other pollution in the atmosphere. In acrylic painting, as your acrylic film is reaching the final dry state, the few evaporating water molecules leave micro-pores on the film, leaving the film tacky to the touch when fully dry. The porous acrylic film accumulates dust and dirt and the best way to protect the painting is by varnish.

A high-quality varnish offers superb quality, remove-ability, and easy and even application. Varnish a painting when it is completely dry. It takes an oil painting a minimum of six months or longer for it to fully dry, depending on the thickness of the film. For an acrylic painting, it will dry between two and a few weeks, again, depending on the thickness of the film.


1. Check if the surface of the painting is clean. Use a lint-free cloth to gently swipe the painting and make sure that no moisture can get on the painting, brush, or the container.

2. Use a 1″ to 4″ varnishing brush. A wide brush is a must so you won’t miss any spot.

3. Place the painting flat on the table so you can varnish horizontally.

4. Dip the brush in the varnish and wipe off the excess on the lid of the container.

5. Apply a thin coat of the varnish in long, even strokes. Stroke back and forth across the painting until the varnish becomes tacky. A little varnish goes a long way. Inspect the varnish and see if there are any bubbles. If there are, even them out immediately.

6. Once you’re done in an area, leave it until you’re done varnishing all the surface of the painting. If you missed a spot, allow the varnish to dry completely and apply another coat of varnish.

7. When done, lean the painting against a wall and put a protective plastic film “tent” to protect it from dust. To test if the varnish is dry or not, touch the edge of the painting to see if it’s still tacky.

Varnish dries at different rates, depending on the weather. In cool, dry weather, varnish dries overnight, while it takes longer to dry in warm, humid weather.


  • Always varnish the painting in one go. If you varnish part-by-part, you’ll end up with lines between the parts you’ve varnished.
  • Look for dust-free workplace so dust will not get into the varnish while you’re applying it.

Image source: EBSQ

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