Best Varnishing Techniques for Acrylic Paintings
To Varnish Or Not To Varnish?
Deciding whether to varnish or not is all up to the artist's desired look for the painting. Varnish changes the surface of the painting, so the finished look you are after should influence your decision.
Should you varnish acrylic paintings?
How Varnish Protects and Improves Acrylic Paintings
Acrylics get quite flat after 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.
Varnish Protects Acrylic Paint's Porous Surface
Acrylic paints don’t need a protective coat to be 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, and 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.
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 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
Advantages and the Disadvantages of Varnishing Acrylic Paintings
- The varnish coating offers UV protection, which help slow the fading of the pigments.
- With varnish the dirt and dust can be removed easily and isn't trapped in the acrylic layer.
- Many artist varnishes can be removed with an ammonia solution. This comes very handy if you have to clean a permanent stain of in case the varnish layer yellows with time, you can remove it and reapply it.
- Varnishes are a great way to even out sheen and pull the whole painting together.
- A varnished painting handles better the battering from handling and shipping.
- Single coats of varnish that even out the entire sheen may not be the original artistic intentions, altering the artwork negatively.
- Sometimes varnishes can be difficult to apply. Some problems being: running varnish, wilting of the artwork, visible brush strokes, formation of bubbles, etc.
- Some varnishes are not removable. If something goes bad during shipping or on display, and the artwork gets stained, you can’t strip the stained varnish off and apply a new coat.
- It's an extra step for the artist.
Tip on photographing your 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.
How to varnish an acrylic painting
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. Other methods, like sponging or rolling may originate problems, such as foaming, non-uniform coverage, releasing of particles from the applicator, etc.
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 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.
Isolation Agent: Acrylic Gel Medium
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 air-spray methods. The latter are 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 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 keeping your pattern consistent.
- For best results, apply 2-3 light coats to achieve your finish, instead of one heavy coat.
Professional Spray Varnish
Varnish Removal, Step-by-Step
Removing a varnish can possibly change and damage the appearance of the artwork, so if it really needs removal, it’s best if left to professional. However, there are times when the artist needs to do the work.
- Check your varnish package to see what kind of remover you need to use. The most common is a solution of household ammonia.
- Make sure you operate in a safe, controlled manner. Work in clean, well-ventilated area. Wear a dual filter respirator, latex gloves, and splash goggles.
- First, test the solvent on a small area of the painting.
- Get a lint free, soft, white cloth, like a 50/50 cotton/polyester, not bigger than 2 square feet. Saturate it with the remover solution and place over an area of the varnished surface. With a plastic sheet, cover the saturated cloth to minimize evaporation.
It’s best to work horizontally. If you are working vertically, find a way to keep the saturated cloth in place on the varnished surface.
- Allow the saturated cloth to lie on the painting for 2-5 minutes, then rub the cloth gently until the varnish starts to dissolve. Be careful not to apply excessive force, as this may damage the paint layers underneath.
- Repeat the procedure, for the entire area to be cleaned. If you see any paint color on the cloth, stop right away and allow the surface to dry.
- Allow painting to dry completely before applying a fresh coat of varnish.
Varnishing or Not Varnishing?
Whether an acrylic painting should be varnished or not is an old dilemma. There are acrylic artist supporting either sides.
While the varnishing is not necessary, I usually do it, both to add a protective layer to my paintings, and because I really like how it makes the painted surface shine homogeneously.
It happens that, in my opinion, glossy varnish looks great and enhances my work. Ultimately it is every artist’s decision to ponder the pros and cons of varnishing and see if their work would benefit from it.
© 2012 Robie Benve