Working with Oil and Acrylic paints has an important benefit that you won’t get with most mediums: they’re ideal to use with varnish.

We’ve talked about some of the steps you can take to protect your artwork, but varnish deserves a post all to itself. It’s the most effective way to ensure your painting is preserved for years to come, but it can also cause irreparable damage if done incorrectly. You might be surprised to find that varnish can also affect the look of your painting in ways you might not expect.

Applying varnish to a painting is a simple process once you get the hang of it, but there are a few things you should keep in mind.

Spray-On vs Brush-On Varnish

There are a couple of key choices you’ll need to make when picking out a varnish, and the delivery method is a good place to start.

Spray-On varnish will apply an even, consistent coat and can be applied quickly, but you lose some of the fine control you get with a brush. It’s also not ideal for paintings with heavy texture, as spray-on varnish can pool in the crevices of brush strokes as it dries.

Brush-On varnish is preferred by many artists as it allows for greater control of the direction and thickness of the application. It’s usually best to apply an even coat of parallel brush strokes across the canvas to get a consistent sheen, but some prefer to follow the brush strokes of the paint so that light reflections accentuate the texture of the piece.

Tip:

• Make sure to always apply varnish in a well-ventilated area. This is doubly important with spray-on varnish. 

Matte, Satin, or Glossy?

Matte varnish will help to protect your painting while keeping glare to a minimum. However, it will lighten your darks and make your blacks less sharp.

Glossy varnish will make your colors pop, deepen your darks and provide a heavy sheen. The downside –  it’s more visible and vulnerable to glare.

If you’re seeking a balance between keeping the colors dark and the highlights bright –  all while maintaining a polished look, Satin is a good in-between option.

Tips:

• Check the manufacturer instructions to be sure, but you can usually mix different sheens to get the exact shine you want.
• If you plan on photographing your work, it’s best to do so before you varnish. Glare can become a frustrating problem with trying to snap a picture of a glossy painting.

Bubbles, Dust and Debris Are the Enemies

Whether from a can or a jar, it’s important that you never shake or jostle varnish. If you’re brushing it on, you need to keep moving across the canvas without backtracking to any sections you’ve already done. If you overwork the varnish, you force small air bubbles into it, and it will start to turn cloudy or milky.

Tips:

• You can save yourself a lot of time and trouble by keeping a specific brush set aside to use for varnish alone. If you use the same brush for both paint and varnish, take special care to completely clean any flecks or residue out of the bristles between uses. 
• Take time to carefully dust off the canvas before you apply varnish.

Test new varnishes and experiment until you’re happy

Varnish will always change the look of a painting in some way and if you aren’t experienced, those changes aren’t always predictable. It can also be difficult or impossible to undo a mistake made while varnishing, so it’s a very good idea to practice, test and experiment with varnish before you start applying it to a piece of cherished artwork.

If you’re using varnish for the first time or trying out a new type of varnish, you should start by using it on a small sample painting so that you know what to expect. Disliked or discarded artwork can make for a good tester.

Tips:

• If you want to know exactly how a varnish will affect a particular painting, create a sample with the same color palette and apply the varnish to that first.