Robie is an artist who loves sharing what she has learned about art and painting in the hope that it might help other creatives.
How Varnish Protects and Improves Acrylic Paintings
Acrylics get quite flat and opaque after they dry. Many times there are uneven areas of shine and matte due to use of different paints, retarders, or other mediums that alter the look of the finished work.
A varnish makes the painting surface more homogeneous, evening out sheen, and intensifies the colors.
Conversely, depending on the effects the artist was trying to achieve, some pieces may lose their character with a unifying varnish, so it’s ultimately the artist’s choice.
Another great advantage of applying a final coat of varnish is that it seals the porous acrylic paint surface, blocking the dirt from collecting.
Dry Acrylic Paint Has a Porous Surface
After they dry, acrylic paints become durable and water resistant. However, during the drying process, the water evaporates from the paint, leaving tiny holes, which are a gateway for dirt and dust buildup over the years.
If you hang your paintings without glass, even if you wipe down and dust your paintings regularly, some amount of dirt gets trapped on the paint surface. Over time, the accumulation can discolor the artwork. A sealant makes the surface dust resistant and easier to clean.
Varnish provides also a UV protection that prevents fading and yellowing of the paint.
While varnishing is not necessary, I always choose to do it. I usually apply a second coat too, just to make the surface a little shinier and the varnishing more homogeneous.
- Timing - Allow a day or two for the acrylic paint to be completely dry, then apply the isolation layer (optional) and wait another day or more before varnishing. If the acrylic paint is thick, like impasto, it’s recommended to wait a couple of weeks before applying the isolating layer or varnish.
- Temperature - Ideally, the temperature should be between 65-75 F, and the humidity between 50- 75%. Too much humidity or cooler temperatures may cause moisture getting trapped between the varnish and paint layers, resulting in whiteness or opacity.
- Application – Acrylic varnishes can be brushed or sprayed. When applying, watch out for foaming, non-uniform coverage, releasing of particles from the applicator, etc. Let them dry flat in a place with no dust, leaves, or other things that might fall on the wet surface.
For varnishing, use a clean, large, and flat painting brush, better if with split end bristles.
Types of Acrylic Varnishes
Acrylic varnishes are either permanent or removable, and they can be applied to both flexible and rigid supports.
Varnish comes in matte, satin, gloss, or high gloss finishes. Glossy varnish usually enhances the colors, while satin and matte varnishes can soften the colors; in fact, matte varnish may actually lighten darker colors.
You can mix them up and acquire your own level of shininess or apply them in layers to obtain the wanted effect.
Video: Varnishing Acrylic Paintings - types of varnishes
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Tip on Photographing Artwork:
If you plan to take photos of your artwork, do it before you varnish.
Varnishes create a shine to the surface that makes your artwork more reflective, thus it gets trickier to take a good photo.
Consider Applying an Isolation Coat Before Varnishing
Before applying your varnish, it is a good idea to apply an isolation coat. However, keep in mind that an isolation coat is permanent and non-removable, and it may cause changes to your artwork qualities.
Reasons why it’s a good idea to have an isolating layer:
- To prevent cloudy or frosted effect when using a matte varnish over an absorbent surface. The frostiness is due to the varnish agent being absorbed into the surface, leaving the matting agent exposed. Isolating the surface stops this unwanted effect.
- To create a physical separation between the painted surface and the varnish. This is particularly important in case the varnish will need to be removed; it keeps the painting protected during the stripping process.
One or more coats of isolation agent may be required, depending on the level of absorbency of the surface. When applying multiple coats, leave 3-6 hours in between coats, and always wait at least one day before varnishing.
It can be applied with a brush or with an air-spray method. The latter is required in case of water-soluble or unstable paints, like pastel or watercolor.
Brush Varnish Application, Step-by-Step
- Wait until the paint is completely dry.
- Work in a dry and dust free room. Clean the painting surface from dust, particles, lint, etc.
- Use a clean, rinsed jar to mix your varnish with up to 25% of water – check instructions on the varnish container. Mix the varnish careful and slowly, to avoid the formation of bubbles.
- Use a clean, large, and flat painting brush, better if with split end bristles.
- Lay the painting flat while varnishing, so the varnish doesn’t run down the canvas and dry uneven. Make sure you protect the surface underneath from drippings.
- Dip the brush into the varnish and apply with regular and even strokes, holding the brush at an angle. Be careful not to overwork it, or it will create bubbles and dry foggy.
- Check the surface looking at an angle to detect areas that are not wet and shiny and go over them with more varnish.
- When you are done, wash the brush and the container with mild soap and rinse well.
- Leave the painting flat until it dries. Allow few hours for the varnish to dry; once dry, double check the surface to see if it has an even glare. You may want to apply a second coat to make it more even or shinier.
Spray On Varnish Application, Step-by-Step
A spray on varnish is always a good option, but it’s the best choice when:
- The painting has textured surface and brush application may result in foaming.
- The artwork has a fragile surface and brush application may be disruptive.
- Spray the varnish in a well-aerated area and possibly wearing a mask.
- Keep the painting upright while spraying. Make sure you cover each area of the painting spraying continuously by moving in a smooth motion, alternating horizontal movements on one coat and vertical on the next. Slightly overlap the spray pattern, to ensure complete coverage.
- During the spray application, maintain the same distance across the surface of the painting, and move your body as well as your ark, to avoid arching the path.
- Apply each coat perpendicularly to the previous one. Turning the painting by 90 degrees helps to keep your pattern consistent.
- For best results, apply 2-3 light coats to achieve your finish, instead of one heavy coat.