How to Varnish a Painting in Oil, Water-Mixable Oil or Acrylic

Learn all about how to varnish an oil painting, a water-mixable oil painting or an acrylic painting.

A varnish is a coating of resin applied to the surface of a painting for protection and appearance. Most paintings in oil, water-mixable oil, and acrylic will benefit from being varnished, both in their appearance and their longevity. Applying varnish is a good skill to learn. There are some basic steps and tools to use. As part of learning the skill of vanishing you may wish to try a few different types of varnish as there are a number to choose from with different characteristics.

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Contents

Saturation and Sheen

Some General Tips

What Can Go Wrong

Varnish Brushes

How to Varnish Watercolour Paintings

 

How to Varnish Oil Paintings

• Types of Oil Paint Varnishes
• Varnish as an Oil Medium Ingredient
• Retouching Varnish
• Final Varnish
• How Dry Does the Painting Have to Be Before It Can Be Varnished?
• Storage During the Drying Period
• What Characteristics to Look for in a Varnish
• Oil Varnish Formats
• How To Varnish an Oil Painting with a Brush-on Varnish
• How To Varnish an Oil Painting with a Spray Varnish
• How To Varnish an Oil Painting with a Wax Paste
• Removing Varnish from an Oil Painting
• Varnish for Paintings Made with Oil Paint on Top of Acrylic Paint

 

How to Varnish Water-Mixable Oil Paintings

• Decide which varnish to use
• How to Varnish Water-Mixable Oil Paintings

 

How to Varnish Acrylic Paintings

• The Two Groups of Acrylic Varnishes
• Sheen of Acrylic Paintings
• How Dry Does an Acrylic Painting Have to Be Before It Can Be Varnished?
• What Characteristics to Look for in an Acrylic Varnish
• Acrylic Varnish Removal
• Isolation Coat
• How To Varnish an Acrylic Painting with a Brush-on Varnish
• How To Varnish an Acrylic Painting with a Spray Varnish
• Varnishing Outdoor Murals
• Fumes From Acrylic Varnish
• Varnish for Paintings Made with Oil Paint on Top of Acrylic Paint

 

 

A poorly varnished painting looks pretty bad, so for your first few attempts you will probably not want to practise on your best paintings. It is not a hard skill to learn, maybe think of learning how to varnish as a small part of learning to paint. Take the time to try different varnishes and different applications and learn what you like best. And don’t take it for granted. Instead of thinking of varnishing as an afterthought, it is good to remember that the varnish is part of the structure of your painting. The longevity of this artwork that you have put so much time, effort and thought into, depends on everything from the support to the varnish. And the varnishing is also the final step of your control over the appearance of your painting.

 

 

Saturation and Sheen

Saturation
Varnish deepens and enriches colours, the same way that wetting a stone makes it look more saturated. For most paintings this is desirable. But you need to decide if this is a change you’d like for your painting. Gloss usually saturates colours more than satin which does it more than matt, but in most varnishes all the sheens will saturate the colours to some degree.

Unifying the Sheen
You can also unify the sheen of a painting. In both oil and acrylics, using differing amounts of glossy mediums as you paint may give areas different sheens and some pigments are more matt than others, so areas of paint with umbers and other earth colours may look dull and matt. Also, in oil paint you can get matt, sunken areas that didn’t have sufficient oil because of: an overly absorbent surface, or not enough oil in the paint mixture, or a thirsty underbound paint layer underneath the new one. If you see this as looking patchy, you may wish to even out the sheen, making it equally gloss or matt all over. If you have intentionally made some areas glossy and some matt, then you will either want to skip varnishing or to varnish the areas using different sheens of varnish.

Note:
Photographing sheen is difficult with still photos. Glare that we see as gloss just shows up on film as a white area. We also see the gloss better than a camera because our eyes are constantly moving a little and we also move our heads. So to show the different sheens on film we’ve had to sometimes take a few photos for each.

 

 

 

Changing the Sheen
If you don’t like the sheen of your painting when you are finished painting and it has thoroughly dried, you can change it to gloss, satin or matt. Gloss varnish can look really nice, like the paint is still wet, really rich and shiny. But there is a drawback, it reflects like glass and the picture can actually be hard to see very well. It also highlights all the ridges and bumps and any unintentional texture which can distract from your intentional marks. A matt surface can eliminate all of this but it can also make some dark areas appear a bit paler, as the matting agent is a white powder, and you need to be very smooth and even with your application or it can look streaky. Sometimes, a mixture of the two to make satin is the best choice to get more of the good points and fewer of the bad. But really, you should decide on the sheen of your finish based on the mood and meaning of the painting and what effect you are after.

 

 

 

 

Matt and Satin Varnish
All varnish starts with a glossy base; matt varnish (and satin to a lesser degree) has matting agents added to it, either a dry particulate matter or a wax. In both acrylic paint varnishes and oil paint varnishes the matting agent usually has to be redistributed into the varnish by agitation, as the matting agent settles to the bottom. It is easier to see this glob of matting agent settled in the bottom if the container is clear. This means that you need to stir or shake the varnish well, often for much longer than you think – as much as two minutes. In both oil and acrylic varnishes, Gloss is thinner than Satin and Matt has the thickest body. (As far as the agitation goes: maybe having your order delivered helps, cos it gets bounced around on its way to you!)

 

 

If you think that you don’t want to varnish your finished work because you don’t want it to look shiny, a mat varnish might be a good choice. A matt varnish can be quite beautiful, almost invisible while enriching the colour. If you want to apply a matt varnish remember that two or three coats will deposit multiple layers of the matting solids which could build up to give a dusty look. The dusty lightening effect is even more visible on dark colours. To prevent this, it’s best to use gloss for the first one or two coats to seal the painting and then only use matt for the second or last coat, which will be enough to knock back all the shine of the gloss varnish, and will reduce some of the matting agent in the layers. With spray varnish I have found that two coats of gloss and one of matt work well. With brush-on varnishes it sometimes takes two coats of matt varnish to get an even, streak-free coating of the matting agent. With all varnishes, you often only need one thin coat of a brush-on varnish, but you usually need at least three coats of a spray varnish.

 

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Some General Tips

• A good soft brush is essential. Take care of your varnishing brush, clean it well and right away because it needs to stay soft.
• When using a varnish that is new to you, test it by just varnishing a corner of the painting first. Let it dry to see if it is what you expected.
• Remember that a few thin coats of varnish are better than a thick one, it needs to dry quickly or it can have problems such as trapping dust, pooling to one side of the painting, running off the edge, drying cloudy, and not drying properly so that it stays sticky.
• The viscosity of the varnish is important. To prevent unwanted brush marks that will usually not go in the same direction as your paint marks, the varnish needs to be able to smooth out, to self-level. So it will need to be thin enough to flow. But on the other hand, it needs to be thick enough to not run off of the edge or be streaky because the resin has been diluted too much. So there is an ideal thickness for each type of brush-on varnish. Most containers will say if the varnish can be diluted and by how much. If you think your varnish is too thick, remember that it takes a surprisingly little amount of additional liquid to make a slightly too thick liquid flow more – often just a few drops. In both oil and acrylic varnishes, Gloss is less viscous than Satin and Matt is the thickest.
• If you think you have just the right viscosity, you may still want to give your finished varnish canvas an ever-so-slight tilt at the beginning before it dries to make sure the varnish levels out. Knowing if this is necessary comes with practice. I will sometimes put a canvas wedge under two corners and keep checking back and then remove them when the varnish has flowed enough, then it flows back and settles evenly, and then let it dry.
• It helps if you position a lamp so that the light rakes across the surface and you can see the shiny parts you have done so you don’t miss a spot and you can see if there are ridges being left by your brush that might indicate that the varnish needs a very slight dilution. (Using raking light, shining from a side angle, to examine your painting is helpful as a final finishing step for the painting phase, as well.)
• If you have used brush-on varnish, when you are finished, wipe away any drips from the sides and back of your canvas or panel with a lint-free cloth. If left, they will dry hard and be difficult to remove.
• Dust is your enemy. Work in a dust-free area and take care to prevent dust settling onto your drying varnish. When the varnish is touch dry you can lean the painting up against a wall with the paint side facing the wall, with just the edge of the painting touching the wall, to finish drying for a few days. This will allow any dust to fall on the back of the painting while the face of the painting is protected. This is a good position for drying paintings in general, that’s why you see so many paintings facing the walls in artist studios. If the paintings are small you can create a drying tower. If you keep your clean brushes upright in a jar, you will want to clean the brush before varnishing as it will have accumulated dust that will become noticeable as you apply varnish. But for oil varnishes you will want the brush to be dry, so wash it a day in advance.
• For both oil and acrylic paintings, some varnishes come with protection from UV light, which means they will help to keep your painting from fading. It does not take the place of using lightfast pigments or keeping a painting out of direct sunlight, but should be used as additional protection.
• Since artist varnish is meant to be removed in the future when it is dirty and a new coat applied, it is helpful to write in permanent marker on the back edge, which varnish you used. The person cleaning the painting in the future will thank you.
• It is best to wait two weeks for a varnish to cure completely hard before handling it.
• You might want to read both the oil and acrylic varnish sections as there is some overlap.

 

 

 

 

 

What Can Go Wrong

If your varnishing has gone wrong you may be able to remove the varnish and try again. Most oil varnishes are removable and will say on the container which solvent to use. However, only a few water-based acrylic varnishes are removable and they often require specialist conservation solvents.

When the varnishing has gone wrong there are usually just a few reasons. By being aware of them you can better avoid them.

• Problem: Gloss varnish is streaky. This might be one of three things. If you over-thin the varnish, there will be places where there isn’t sufficient resin, similar to not having enough binder in paint. These areas will be less shiny. Or it could be that you missed some areas with the brush. So be sure to have raking light shining across as you apply the varnish so you can see if you have missed a spot. Or it could be that you kept brushing the varnish after it started to dry, which can change the sheen. (Advanced varnishers can use this last trait to their advantage and ‘overbrush’ varnishes to intentionally change the sheen.)
• Problem: The varnish has pooled up in the paint texture and these thicker areas of varnish are cloudy and later take on a yellow tint. This happens because the varnish was applied too thickly. Either the layer was not brushed out thinly enough or the varnish was not runny enough. You might want to use a spray varnish for paintings with a lot of texture.
• Problem: The container says Satin or Matt but the dried varnish is glossy or streaky. This is because the matting agent wasn’t stirred or shaken well enough. Spray varnishes in particular need a good long shaking.
• Problem: The painting wasn’t completely dry when a final varnish was applied. For oil paintings this may become noticeable in the future as the painting tries to dry under the varnish and there is bubbling or cracking. For acrylic paintings it will become noticeable sooner as the varnish becomes cloudy.
• Problem: The painting and/or brush were dusty and dust got smeared around on the painting in the varnish. Both brush and painting need to be carefully cleaned before varnishing begins. For oil varnishes, wait a day after cleaning for both brush and painting to be thoroughly dry, so as not to trap water in the varnish.

 

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Varnish Brushes

• A good varnish brush is soft, flat, wide, and usually thin rather than thick. They usually have short handles and you apply the varnish with the brush held at a low angle. Jackson’s White Synthetic Mottler is an excellent choice.
• Keep a separate brush for varnishing and wash it right away after use. Keep it as soft and clean as you can.
• Be sure to rinse any dust off your brush before you begin varnishing; brushes stored in open pots get surprisingly dusty and it can become visible if you start smearing it around on your painting. Dry the brush thoroughly before using it with oil varnishes.

 

 

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How to Varnish a Painting in Oil, Water-Mixable Oil , or Acrylic.

There is specific information for varnishing each painting medium, and different materials to use. Here you will find information about the different varnishes for each medium and step-by-step guides.

 

Varnishing Watercolour Paintings

It is not necessary to varnish a watercolour painting and varnishing is not usually done for traditional watercolour paintings. A watercolour is usually framed with glass to protect it. But recently there has been some interest in varnishing watercolour paintings because some artists would like to paint on canvas or mount the paper on wooden panels and want to show their paintings without glass, and they like the different look of a watercolour that has been varnished. So, it is unusual, but if you would like to try it, here is our guide to Watercolour Varnish.

 

How to Varnish Oil Paintings

Oil Paint Varnishes

In oil painting, a varnish is a resin dissolved in a solvent to become a liquid for use in painting. Historically, resin was the dried sap of a tree and is a translucent light yellow or amber colour. Many coniferous and hardwood trees have been used for resin and the resins included: Copal, Larch Venice, Mastic, Dammar, and many others. Modern synthetic resins, including alkyd and ketone resins, have largely replaced the traditional natural resins, though a few types are still available. The most common natural resin still in use in Dammar. Synthetic resins are considered superior to natural resins because they do not yellow or crack as they age like natural resins do, and they only require a mild solvent such as odourless mineral spirits to dissolve, whereas the natural resins require a strong solvent such as turpentine.

There are three kinds of varnishes used in oil painting:

Varnish as an Oil Medium Ingredient

Not all varnish is a final coating for a painting. You may have seen recipes for making your own oil painting mediums that call for Damar Varnish as an ingredient. (Damar is also spelled Dammar, so you may need to search both terms to find all the products.) Some oil painting mediums (which means they are meant to be mixed with the paint) have a varnish in them. If the medium contains a natural resin such as Damar or Canada Balsam, the hardened gum must first be turned into a varnish (meaning dissolved in a solvent to make a liquid from the solid resin), then it can be added to linseed oil to make a painting medium. There are a few different oil painting mediums to modify different properties of the paint. An oil painting medium may be just oil, or may also contain a solvent, or may have the third ingredient of a resin. For oil mediums that do contain resin, it has been added for the purpose of allowing better adhesion of fresh paint to a previous layer of dried paint, for artists who paint in layers over a long period of time. This also means no beading up of the new paint layer. Some painters also feel there are attractive visual properties to paint that has resin in it.

Read more about this in our article How to Make Dammar Varnish

Dammar Varnishes at jacksonsart.com.

 

Retouching Varnish

There is a thin kind of varnish that you apply to the painting surface in a thin coat, that is called retouching varnish. Being thin and applied lightly means there is only a diluted coating of resin on the surface of the painting. This thin layer doesn’t seal the painting like a final varnish does, so allows the oil paint to continue to receive oxygen and harden (or dry). This means that you can apply it before the painting is fully dry, which is very different to final varnish. The thin layer also doesn’t affect the sheen very much.

Retouching varnish can be made with natural resin, like Damar Retouching Varnish, or with synthetic resin which is more common.

Traditionally there are three uses that painters have for retouching varnish:

They apply it to areas that are sunken and dull to revive them. A sunken area either doesn’t have enough oil or parts are drying at different rates and the quicker drying areas may look matt. A thin coat of retouching varnish can correct this appearance. But a better solution is to prevent an area of paint from sinking by making sure there is enough oil to bind the paint by ensuring that the surface isn’t too absorbent for the amount of oil in the paint, and that there is a little extra oil in the earth colours, which can be less oily by nature.

Retouching varnish is used to give some protection from scratches to the surface of a painting that isn’t fully dry, during the waiting period before a final varnish can be applied. This way a painting can be exhibited with less fear of it being damaged. It should be used in as thin a layer as possible, too many layers or a thick layer will be similar to a final varnish, which you don’t want. Because the painting is not fully dry, brushing solvents over the surface can dissolve some areas of paint so I recommend using a spray retouching varnish when using it like this as an early protective coating. Then when the painting is fully dry, the retouching varnish does not need to be removed (it probably cannot be removed since it was applied to paint not fully dry, it will have melded with the paint). When you are ready to apply the final varnish, just clean the surface and apply the final picture varnish on top of the retouching varnish.

Artists often apply retouching varnish to a thoroughly dried paint layer to aid adhesion of a fresh paint layer, which otherwise might bead up or not adhere well as it dries because the layers are too different, the dried paint layer is ‘closed’. (I have experienced poor adhesion where after the new paint layer was dried it could be scratched off easily with a fingernail.) This use is where the name Retouching comes from. While painting more oil paint on top of a final picture varnish is not recommended, retouching varnish is meant to be different. If a final picture varnish is applied between layers of paint it may cause the paint to become less resistant to solvent, even when the paint is fully dry. This may create a risk of the paint being removed more easily if the final varnish is ever removed in the future – because as oil paint dries, it becomes more and more resistant to solvents, more permanent, but the varnish continues to be vulnerable to solvent always, because it is meant to be removable.

But, not many retouching varnishes claim anymore that you can paint over the varnish, only some do. The original retouching varnish was damar varnish diluted with twice the usual amount of turpentine. It would be applied to small areas to be repainted and the damar bonded with the dried paint layer better than synthetic resin varnishes do. You want your final varnish to be easily removable for future cleaning, but you want your retouching varnish to be hard to remove. So it makes sense to use a damar retouching varnish for adding paint on top of as it is made with strong turpentine. (And only apply it where you need to add paint). And then use a synthetic varnish for your final varnish as it will only need a milder mineral spirits to remove it. An even better solution to the adhesion problem, if you paint in layers, is to mix in with all your paint layers an oil painting medium that contains resin.

Retouching Varnishes are available in aerosol spray cans or as liquids to be brushed on.

 

 

Final Varnish

The third kind of oil varnish is a final varnish, the product most people think of as ‘varnish’. For use on oil paintings it is also called Picture Varnish. Applying a final picture varnish to your fully dried oil painting will provide many benefits.

A final varnish will:
1. Protect the dried oil surface from scratches.

2. Accept the pollutants and dirt of the years and when dirty be removable from the painting so it can be replaced with a new clean layer.

3. Deepen the saturation of the oil paint that can begin to look drier and chalkier as it dries (I think they sometimes look thirsty).

4. Even out the surface sheen or change it to matt, satin or gloss.

5. Seal the painting from absorbing any more oxygen and becoming overly dried out, which means in effect that you will be slowing the ageing process.

6. Allow it to be more easily wiped clean.

 

 

How Dry Does the Painting Have to Be Before It Can Be Varnished?

The best practice is to wait to varnish your oil painting until it is thoroughly dry because if you apply varnish before the paint is fully dry the varnish will meld with the still drying paint and no longer be a separate removable layer. It will also form a hard layer on top of a still changing lower layer and that can result in it cracking or wrinkling as the changing oil paint pushes and pulls on it. If you seal the painting, then it can’t absorb the oxygen it needs to form the bonds that make it a strong surface.

There is some confusion about how long you need to wait for an oil painting to be thoroughly dry. The long-standing rule is that it is safest to wait 6-12 months, but it can be longer if the paint is very thick or the environment is very humid and it can be a bit shorter if you’ve used fast-drying mediums, alkyd oil paints, or have painted very thinly. Gamblin, the makers of the great varnish Gamvar, believe that the 6-12 month rule is too vague and doesn’t take into account the huge difference between the drying time of a painting made with a paint mixed with a fast-drying medium and applied thinly or lightly (much less than 6 months to dry) and a painting with slow-drying colours or mediums and painted thickly (much more than 12 months to dry). They also point out that the 6-12 month recommendation originated before the fantastic synthetic varnishes we have now, like Gamvar which is a Regalrez-based varnish. The old natural resin varnishes were both brittle and needed very strong solvents, unlike the synthetic varnishes today that use the more gentle odourless mineral spirits. Gamvar is an excellent varnish because it is a flexible, synthetic varnish that will not yellow. But there is a current misconception among many oil painters that I have spoken with that it has unusual properties that allow it to be applied when the painting is only touch-dry. This is not true, so I wanted to mention it in particular. Some artists think that if you use Gamvar you can varnish in just one to two weeks, when the painting is just touch-dry, because their varnish has a special quality that allows oxygen through. But all final varnishes let some oxygen through. Gamblin say ‘Gamvar can be applied when the thickest areas of your painting are thoroughly dry and firm’. Gamvar is excellent but it is not magical and cannot be applied any sooner than other similar synthetic varnishes.

 

 

Most artists want to varnish sooner than is recommended, they need to sell the painting or exhibit it and waiting months is a frustrating problem. If you are one of these artists then a few small changes might mean that you may be able to varnish in as soon as two months – apply your paint more lightly and mix it with a small amount of a fast-drying alkyd medium. There are a few different ways to test the dryness of a painting, these include: pressing your thumbnail into the thickest part looking for no indentation, pressing the flat of your thumb into the surface and twisting, looking for no change, and wiping with a solvent to test for colour removal. I generally go by how long it has been, how thickly I painted and what fast or slow drying mediums I used, and if I’m not sure I will gently press a nail into a thick area hoping for no mark. If I have an exhibition coming up then I give myself a varnishing deadline as part of the process, so oil paintings made with a fast drying medium need to be finished at least 2 or 3 months before. (It’s useful to have them ready early for publicity photos, as well.) If I can’t do that, which is often the case, then I use a thin spray of retouching varnish now and a final varnish later.
 

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Storage During the Drying Period

While you are waiting the six or more months for an oil painting to dry before you can varnish it, it needs to be out of the way and protected from spatters or collecting dust. Even if it is touch dry already, covering it tightly in plastic will stop it receiving the oxygen it needs to finish drying, any paper laid on it will usually end up stuck to it, and bubble wrap can leave an impression of its pattern on the surface.

So it is best to leave them unwrapped but sheltered from dust. If you have just a few small paintings, then you can store them flat, face-up on a shelf in a closed cupboard or in the gap across the tops of books in a bookshelf, or vertically in a homemade divider or something similar to a letter rack or LP rack. If they are large, then you can simply tilt the face to the wall on the floor, usually elevated on blocks to prevent the lower part collecting dust blowing around on the floor.

Drying Tower
For small to medium works, I have developed a version of a sort of tower of drying space using a stack of gator boards or other thin, rigid panels, separated by four objects, one in each corner (or three in a triangular formation), such as large canvas wedges, water bottle caps, small yoghurt cups or similar, just as long as all four corners are the same and tall enough to lift the next board above the surface of each flat painting, while leaving the smallest gap possible between the flat painting and the ‘roof’ above it. Place a wet painting plus four objects taller than the flat painting on a board, then place another board flat on top of the corner objects and repeat until you have a tower of flat, protected paintings. This works both for drying varnish and for the longer process of drying oil paintings.

 

 

 

What Characteristics to Look for in a Varnish

The best varnish to use will:

1. Not change in appearance over time (yellow or darken or become cloudy).

2. Remain very flexible because as the top layer of the painting structure it should be the most flexible layer of the painting.

3. Remain removable with a solvent that will not remove the underlying paint.

4. Some varnishes also offer UV protection.

A final varnish made with a synthetic resin is generally considered better than a natural tree sap resin (damar, copal, mastic, etc) because it will not change over time becoming darker or yellow, brittle, or less removable over time. The most readily available natural resin varnish is Damar Varnish and it will say Damar in the name. If it doesn’t say, then it is synthetic. Some artists like Damar varnish because it is very glossy and usually flows very well, so you can get a nice, thin even layer.

 

Oil Varnish Formats

Final varnishes are available as liquids that are applied with a brush, in aerosol spray cans, and as wax pastes in jars that are applied with a cloth. Each has different qualities and pros and cons. With a brush-on varnish you can mix your own sheen, you can apply more varnish to get a high gloss and greater protection, you may only need one coat, and it is more economical. A can of spray varnish doesn’t go as far, applies a very thin layer so needs at least three coats, and requires very good ventilation but is good for highly textured paintings and is easiest to apply well. Paste wax varnishes only come in matt and have a particular appearance. Most oil varnishes will have strong solvents and you will need good ventilation. You may want to vacate the room for a time after you have varnished and let it air out.

 

 

Brush-on Varnish

A brush-on liquid is the traditional format but it can be slightly trickier than the other two formats for the beginner to get a perfect streak-free and brushmark-free finish. With practice you will find a favourite brand and know how much to thin it, how thickly to apply it, how quickly each coat dries, and if you need more coats. Most brands do a Gloss and a Matt sheen and some also do a Satin. If a brand doesn’t do Satin they usually advise that you can mix Gloss and Matt to make a Satin. I have found that it is not a 50:50 ratio when doing this, it can take 20% Matt and 80% Gloss to make a Satin, as the matt is usually very pervasive. And of course you can customise your mixture to make a glossy satin or a nearly matt satin by varying the proportions. Brush-on oil varnish is easier to get right than brush-on acrylic varnish because it is very fluid, so it levels out well and it takes a few hours to set up, so you have time to brush it out evenly.

 

 

Aerosol Spray Varnish

Spray varnishes are easy to use and get a streak-free finish. The coating you get is much thinner than with a brush-on varnish so although it won’t give as thick a layer of protection it also won’t fill in any texture, so are good for impasto paintings. You must shake the can often during the process. There are considerable fumes and the task should not be undertaken indoors without excellent ventilation. I do it outdoors using a clean cardboard box to help keep the spray from blowing away.

 

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Rub-on Wax Paste Varnish

Because they contain wax, all wax paste varnishes have a matt sheen and when dry can be buffed with a lint-free cloth to a soft satin sheen. They are applied with a stiff varnishing brush or a cloth and then rubbed in with a cloth. They are easy to apply and hard to get wrong.

 

 

How To Varnish an Oil Painting with a Brush-on Varnish

Decide which varnish to use: and choose your sheen, or mix one in between.

Wash and dry your brush the day before: it needs to be well dry. While your brush may look clean, a brush gets dusty quickly especially if stored in an open jar and it’s an unwelcome surprise when you start seeing fibres and bits of dust as you are brushing the varnish. If this happens, quickly remove the wet varnish, wash your brush, and start again. See previous brush section.

Be sure your paint is dry: Before varnishing, after you have waited at least six months, test for dryness using one of the methods mentioned earlier: pressing your thumbnail into the thickest part, pressing the flat of your thumb in and twisting, or wiping with a solvent to test for colour removal.

Clean the surface: Clean the surface well with water to remove any dust, dry it and give it a good wipe with a lint-free cloth with mineral spirits to wipe away any grease or built up residue. Check the cloth for telltale signs of colour being removed that will indicate parts of the painting aren’t yet dry. Let it dry well, a few hours to be sure all water has left the surface so none will be trapped in your varnish layer. Propping it near a radiator to helps.

Set up your varnishing area: Varnish flat on a table. You may wish to cover the table with a protective sheet. You will get drips on the edges so have a cloth, kitchen paper or sponge to wipe those away, also useful for wiping excess varnish from your brush. A lamp set up from the side to shine raking light across the surface will help you see if you have missed any spots. Choose a place to put it while it dries. If it’s big, I usually leave it where it is and create a roof over the top to protect it from dust. So I prepare the roof in advance – a clean stiff surface propped across four pots of paint or old yoghurt cups. When it is touch dry I move it to sit on pots and lean facing the wall.

Stir or gently shake if you are doing your final coat in matt or satin varnish: Then let any bubbles settle. If your satin or matt varnish dries glossy, then you didn’t mix the matting agent in thoroughly enough, it is sometimes a thick glob sitting at the bottom. Stir or shake more thoroughly and apply another coat.

Pour your varnish into a clean dish or wide jar. Some artists pour the varnish directly in a puddle onto the painting, but it can be harder to get an even coating when you start with all the varnish in one place and you are more likely to apply too much. If it is too thick, thin it very slightly to a more fluid consistency. It should not be thick like honey. It should be fluid.

Dip your brush into the varnish and wipe the excess off on the edge of the container. Brush on the varnish, across the painting in long even strokes, using a slow gentle motion to prevent foam forming on the surface of the painting. Your brush should be at a low angle. Cover the surface evenly and thinly from the top left corner, going across, working your way down until you end at the bottom right corner. Your brush should have very little varnish on it, you are applying it sparingly. You may find that when you come to the end of the stroke across the painting, that rather than dipping in for more varnish you may just need to flip the brush over and use the varnish on the other side. You can go back over the painting again and along the edges to make sure it is all even. Work quickly but gently and methodically. Check it against the light as you smooth it out. If it seems to be drying then stop. Let it dry and do a second coat rather than continue to brush this one.

Let dry to the touch (this may take a few hours). Check it in a good light and if it looks good you are done. If it is not covered evenly or you want a deeper finish, you can repeat the procedure. Be careful not to do your second coat until the first one is dry or it will be too easily reactivated by the solvent in the wet varnish. Each layer must be applied quicker than the previous one and more gently with less brushing, to not disturb the previous layer. Two or even three thin coats are better than a thick one which can take forever to dry, become cloudy, pool up on one side of the painting or fill in your brushstroke texture, and is more likely to show if it yellows.

Wipe any drips from the sides and back of your canvas or panel.

Leave to dry, flat and protected from dust. See Drying Tower above.

Write in permanent marker on the back of the painting near the edge, the type of varnish you used so they will know how to remove it if needed in the future.

Remember: If you are a first time varnisher, do a few of your less important paintings first to get a feel for it.

 

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How To Varnish an Oil Painting with a Spray Varnish

Decide which varnish to use: and choose your sheen. You may wish to use a Gloss followed by two coats of Satin. Use spray particularly if your painting has lots of impasto texture as the varnish will not pool in the low spots.

Be sure your paint is dry: Before varnishing, after you have waited at least six months, test for dryness using one of the methods mentioned earlier: pressing your thumbnail into the thickest part, pressing the flat of your thumb in and twisting, or wiping with a solvent to test for colour removal.

Clean the surface: Clean the surface well with water to remove any dust, dry it and give it a good wipe with a lint-free cloth with mineral spirits to wipe away any bloom. Check the cloth for telltale signs of colour being removed that will indicate parts of the painting aren’t yet dry.

Apply: I apply spray varnish to large paintings with the painting vertical, first in one direction and after it has dried to the touch, in the perpendicular direction. Being sure to keep the can the same distance from the surface as it moves. Spray varnish applied lightly dries quickly and you can usually do a second coat after 3-15 minutes. It may be easier to have a consistent spray if you rotate the canvas a ¼ turn, rather than change direction of your spray. Keep spraying past the edge. Since this means that there will be overspray and there will be a layer of varnish around the painting on your wall, so you might wish to protect the wall. You will need ventilation, most spray varnish is very smelly and not good to breathe. If you can, take it to a sheltered place outside or an outbuilding and leave after each coat.
If it is small I take it outside and spray in a clean cardboard box. I put three flaps of the box up to create a wind shield, spray from the other flap and then quickly close all the flaps of the box and leave it to become touch dry. You will want to do a test run to be sure that when you close your flaps they don’t come in contact with the painting. Closing it up while it dries also means that no leaves of insects come in contact with the painting. Repeat twice.

 

 

 

How To Varnish an Oil Painting with a Wax Paste

Decide which varnish to use. Some need a gentle warming in a warm water bath. Check the instructions.

Be sure your paint is dry: Before varnishing, after you have waited at least six months, test for dryness using one of the methods mentioned earlier: pressing your thumbnail into the thickest part, pressing the flat of your thumb in and twisting, or wiping with a solvent to test for colour removal.

Clean the surface: Clean the surface well with water to remove any dust, dry it and give it a good wipe with a lint-free cloth with mineral spirits to wipe away any bloom. Check the cloth for telltale signs of colour being removed that will indicate parts of the painting aren’t yet dry.

Apply: If it’s the type that is applied cold, then scoop some out with a firm varnishing brush such as the DaVinci Impasto brush, brush it on and then rub it in with a lint-free cloth. If it needs to be warmed then it will liquify and you apply it with a brush. Let dry for 24 hours. Polish with a soft cloth to a satin sheen and to help the varnish achieve a firm surface.

 

 

 

Removing Varnish from an Oil Painting

Artist’s oil varnishes should be removable when they are dirty so that a fresh clean varnish can be applied. But that doesn’t mean they will be easy to remove. The varnish will usually be removed by a professional restorer in the distant future. If you are doing it yourself because you have made a bad job of applying the varnish, realise that it is not a quick thing to do. It should be done gradually and you need to be respectful of the painting. The container of varnish will say which solvent will remove the varnish. Wear gloves and use a lint-free cloth, work slowly and gently. You will need to let it dry and check it against the light for changes in sheen and then work at it some more.

 

Varnish for Paintings Made with Oil Paint on Top of Acrylic Paint

Varnishing an oil painting and an acrylic painting have many things in common. But they do use different products. Just as you cannot paint in acrylic on top of an oil painting, you cannot use a varnish that is intended for acrylic paintings on an oil painting. But as with paint you can put oil varnishes on top of acrylic paintings. So a painting done in oil on top of acrylic, even if lots of acrylic is left visible, should be varnished with an oil painting varnish.

 

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How to Varnish Water-Mixable Oil Paintings

In many ways a painting made with water-mixable oils should be treated the same as a painting made with conventional oils. After a few hours, when the water has evaporated from the paint film (if you used any water), then the painting is essentially simply an oil painting. After you’ve waited the six months or more for the painting to be completely dry, you can varnish it with a conventional oil paint varnish or a varnish specifically made for water-mixable oils.

Although varnishing a water-mixable oil painting can be similar to varnishing an oil painting, there are a few differences to consider. One of the differences is that most brands of water-mixable oils stay somewhat sticky, even after they have dried. This can range from feeling slightly tacky to very sticky (this can be confused with not being dry). This makes varnishing them even more important than for conventional oils, because a varnish will give the painting a hard surface that doesn’t attract dust and can be wiped clean. The second thing to consider is that one important reason that painters choose to use water-mixable oils is to avoid the fumes that you usually get with oil paint solvents. So they may also wish to avoid the fumes from oil paint varnishes. There are two makes of varnishes especially for water-mixable oil paintings: an Artisan brush-on varnish and a Cobra spray varnish. These have lower fumes than conventional oil varnishes.

 

 

Decide which varnish to use: conventional picture varnish or water-mixable oil varnish. You can use conventional picture varnish for water-mixable oil paintings but the water-mixable oil varnishes do not contain conventional solvents, so, like the water-mixable oils themselves, they are great for shared spaces and for artists that are avoiding the use of hazardous solvents. The water-mixable oil varnishes can be used on conventional oil paintings as well as water-mixable oil paintings.

Be sure your paint is dry: Before varnishing, after you have waited at least six months, test for dryness using one of the methods mentioned earlier: pressing your thumbnail into the thickest part, pressing the flat of your thumb in and twisting, or wiping with a solvent to test for colour removal.

Clean the surface: Clean the surface well with water to remove any dust, dry it and give it a good wipe with a lint-free cloth with mineral spirits to wipe away any bloom. Check the cloth for telltale signs of colour being removed that will indicate parts of the painting aren’t yet dry. Make sure your cleaned brush and painting are thoroughly dry, you may want to do this 24 hours in advance.

Apply: Apply as for brush-on or spray varnish for oils, in the oil varnishing section above.

 

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How to Varnish Acrylic Paintings

 

Unlike oil varnish which is only solvent-based, there are both water-based and solvent-based acrylic varnishes (sometimes called mineral spirit acrylic varnishes MSA). A water-based polymer varnish will allow the painting to slowly continue to cure so there is less likelihood of the varnish going cloudy, but many are not removable, and an MSA varnish will provide a harder, more durable finish that can be removed later with solvents, but the painting must be very well dried and cured before applying the varnish or it may bloom (become cloudy over time). Both types are available as liquids to brush on or as aerosol sprays. As with all varnishes, you often only need one thin coat of a brush-on varnish, but you usually need at least three coats of a spray varnish.

 

I don’t consider my acrylic paintings finished until they are varnished. I find that acrylic paint stays soft and porous. If you use gloss mediums, the painting can often stay sticky even after it’s dry. This means that the surface gets easily damaged because it sticks to anything and bits of paint can even come off when you pull two stuck together paintings apart. It also attracts dust that embeds in the surface and even museums find it challenging to clean unvarnished acrylic paintings. Applying a layer of varnish seals it with a hard, non-sticky layer that prevents sticking together in storage and makes it easy to wipe clean on display.

 

Sheen of Acrylic Paintings

Each pigment needs a slightly different proportion of ingredients and this causes differing levels of shine for different colours of paint. If you use more than one brand in a painting that can make even a bigger difference in the shine of each colour as some makes are more matt than others.

Since I don’t usually intend for certain colours of my acrylic paintings to be more matt than others I like my final painting to have an even sheen. If you apply an isolation coat to separate the painting from the varnish, that will give you an even gloss sheen, which while also protecting the paint surface during future varnish removal, also gives you an even sheen to begin varnishing. But gels are even softer and stickier than acrylic paint. So a final varnish in your preferred sheen will add that helpful harder layer. I like a slightly glossy satin finish. So I mix 80% Gloss with 20% Satin which results in a satin finish with a slight gloss.

 

How Dry Does the Painting Have to Be Before It Can Be Varnished?

Don’t forget that acrylic paint takes longer to cure than you might think. It dries to the touch quickly, so painting with it uses a faster technique and you need to keep your brushes wet. But the curing of a finished painting is done by polymerisation like oil paint and you should wait at least 72 hours before varnishing an acrylic painting. It can take up to a month for an acrylic painting with thick paint or lots of gel to be dry enough to varnish. If you used a retarder or any of the slow drying acrylics, it could be even longer. I have used thick layers of gel that have taken 3 months to go from cloudy to all the way clear. If you varnish too soon you can trap in volatiles that want to be released and your varnish may become cloudy.

 

 

Because acrylic paintings are so soft and sticky they attract dust over time, as well. Museum conservators are finding it difficult to clean the acrylic paintings from the 60’s whose porous, sticky surfaces have trapped a lot of dust. A coat of varnish will provide a smooth hard finish reducing the tackiness of the surface so less dust and dirt will stick, it will make it easier to wipe clean over the years, and in the far future some conservator may thank you, when all they need to do is carefully remove your varnish and the painting will be like new! Here is a great technical article on acrylic painting conservation.

 

 

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Acrylic Varnish Removal

Unlike solvent-based varnishes, only a few water-based acrylic varnishes are removable.

The rule has always been that artist-quality varnishes should be removable when they are dirty so that a fresh clean varnish can be applied. This is true of all oil varnishes and all solvent-based acrylic varnishes, but many water-based acrylic varnishes that are labelled professional quality, are not removable, at least not by artists in the studio. If you choose a professional varnish that is removable, remember that it doesn’t mean that it will be easy to remove. The varnish will usually be removed by a professional restorer in the distant future and may need conservator-level solvents. If you are doing it yourself because you have made a bad job of applying the varnish, realise that it is not a quick thing to do. It should be done gradually and you need to be respectful of the painting. Now that Golden no longer makes their Polymer Varnish that was removable with household ammonia, there are not many water-based acrylic varnishes that can be removed in the studio.

 

Isolation Coat

An isolation coat of clear acrylic polymer acts as a protective barrier and is recommended to go between the painting and the varnish. Soft Gel is a good choice for an isolation coat or a fluid polymer medium in gloss such as Jackson’s Fluid Medium Gloss and Golden now make a product called Isolation Coat. Use a gloss medium and not a matt medium which will leave a hazy white layer. Apply it quickly and evenly over the whole painting following the original brush marks of the paint. Allow to cure for several days or weeks before varnishing.

Golden has a good video showing how to do this.
Golden says an isolation coat under a matte varnish also helps prevent the white layer of the matting agent from showing as much.

 

What Characteristics to Look for in an Acrylic Varnish

The best varnish to use will:
1. Not change in appearance over time (yellow or become cloudy)
2. Remain very flexible because as the top layer of the painting structure it should be the most flexible layer of the painting
3. If possible, remain removable with a solvent that will not remove the underlying paint
4. Some varnishes also offer UV protection

 

 

How To Varnish an Acrylic Painting with a Brush-on Varnish

Decide which varnish to use. Solvent-based or water-based. Brush-on or spray. We are using a brush-on varnish here.

Be sure your paint is fully dry and cured. Thick areas of paint or gels can take months to release all water and volatiles. If you used a retarder it could take longer.

Clean the surface well with water to remove any dust, dry it. If using a solvent-based varnish, dry it very well, perhaps leaving it for 24 hours to be sure it’s dry.

Wash your brush and if using a solvent-based varnish, be sure the brush is dry. While it may look clean, a brush gets dusty quickly and it’s an unwelcome surprise when you start seeing fibres and bits of dust as you are brushing the varnish. If this happens, quickly remove the wet varnish, wash your brush, and start again. See previous brush section.

Set up your varnishing area. Varnish flat on a table. You may wish to cover the table with a protective sheet. You will get drips on the edges so have a cloth, kitchen paper or sponge to wipe those away. A lamp set up from the side to shine raking light across the surface will help you see if you have missed any spots. Choose a place to put it while it dries. If it’s big, I usually leave it where it is and create a roof over the top to protect it from dust. So I prepare the roof in advance – a clean stiff surface propped across four pots of paint or old yoghourt cups.

Agitate matting agents. Stir or shake if you are doing your final coat in matt varnish. Then let any bubbles settle. If your satin or matt varnish dries glossy, then you didn’t mix the matting agent in thoroughly enough. Stir or shake more thoroughly and apply another coat.
Apply. Pour your varnish into a dish. If it is too thick, thin it to a more fluid consistency. It should not be thick like honey.
Brush out the varnish in even strokes, using a slow gentle motion to prevent foam forming on the surface of the painting. Cover the surface evenly and thinly. If you apply the varnish too thickly it will crack as it shrinks. See photo below.

Drying for second coat. Water-based polymer varnishes may not take very long to dry to the touch, but if you are applying a second coat I would wait a few hours to be sure that the first layer is dry because the varnish could be reactivated and parts of the dried resin can be picked up and moved, leaving jagged areas that no longer have a first coat and the surface looks cratered and awful. The speed of drying, how long you can brush for and how soon you can apply a second coat safely, are the hard parts of a brush on water-based acrylic varnish.

Two or three thin coats are better than a thick one which can take forever to dry, become cloudy, pool up on one side of the painting or fill in your brushstroke texture, and is more likely to show if it yellows.

Wipe any drips from the sides and back of your canvas or panel.

Leave to dry, flat and protected from dust. The recommended time for curing of the finish before handling or wrapping is usually two weeks.

Make a note. Write in permanent marker on the back of the painting near the edge, the type of varnish you used so they will know how to remove it if needed in the future.

Remember: If you are a first time varnisher, do a few of your less important paintings first to get a feel for it.

 

 

 

How To Varnish an Acrylic Painting with a Spray Varnish

Decide which varnish to use: and choose your sheen. You may wish to use a Gloss followed by two coats of Satin. Use spray particularly if your painting has lots of impasto texture as the varnish will not pool in the low spots.

Be sure your paint is thoroughly dry and cured: Thick areas of paint or gels can take months to release all water and volatiles. If you used a retarder it could take longer.

Clean the surface well with water to remove any dust, dry it. If using a solvent-based varnish, dry it very well, perhaps leaving it for 24 hours to be sure it’s dry.

Apply: I apply spray varnish to large paintings with the painting vertical, first in one direction and after it has dried to the touch, in the perpendicular direction. Being sure to keep the can the same distance from the surface as it moves. Spray varnish applied lightly dries quickly and you can usually do a second coat after 3-15 minutes. It may be easier to have a consistent spray if you rotate the canvas a ¼ turn, rather than change direction of your spray. Keep spraying past the edge. Since this means that there will be overspray and there will be a layer of varnish around the painting on your wall, so you might wish to protect the wall. If you are using an MSA spray varnish you will need ventilation, it is very smelly. If you can, take it to a sheltered place outside or an outbuilding and leave after each coat.
If it is small I take it outside and spray in a clean cardboard box. I put three flaps of the box up to create a wind shield, spray from across the other flap and then quickly close all the flaps of the box and leave it to become touch dry. You will want to do a test run to be sure that when you close your flaps they don’t come in contact with the painting. Closing it up while it dries also means that no leaves of insects come in contact with the painting. I leave the can on top to hold the flaps closed. Repeat twice.

 

 

Varnishing Outdoor Murals

Acrylic paint is a good choice for painting a mural because it adheres well to a well-prepared surface, can withstand weather if varnished properly, dries quickly and can be cleaned up easily with water. For a long-lasting mural you will need to prepare the surface well, use paints with lightfast pigments and it is very important to seal it to protect it from the weather conditions and sunlight. Golden MSA (Mineral Spirit Acrylic) is recommended for varnishing outdoor murals because it has UVLS (Ultraviolet Light Stabilizers) and provides a very durable finish. It’s a Mineral Spirit Acrylic Varnish and is recommended for interior and exterior use and comes in an aerosol spray or in a tin to be diluted with turpentine and brushed on. Be aware that not all solvents will dilute the Golden MSA Varnish – you may wish to read our earlier article Diluting MSA Varnish to learn about which solvents will work.

 

Fumes From Acrylic Varnish

Unlike oil varnish which is only solvent-based, there are both water-based and solvent-based acrylic varnishes. The two types are really different in terms of fumes and the need for ventilation. If using mineral sprit acrylic varnishes indoors, you will need excellent ventilation. You might also want to consider using the MSA varnishes a few weeks earlier if you intend to ship the painting, because the odour remains for a long time and the recipient may open the box to strong smells.

 

Varnish for Paintings Made with Oil Paint on Top of Acrylic Paint

Varnishing an oil painting and an acrylic painting have many things in common. But they do use different products. Just as you cannot paint in acrylic on top of an oil painting, you cannot use a varnish that is intended only for acrylic paintings on an oil painting. But as with paint you can put oil varnishes on top of acrylic paintings. So a painting done in oil on top of acrylic, even if lots of acrylic is left visible, should be varnished with an oil painting varnish.

 

 

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Further Reading

Tina Mammoser’s blog

Golden Artist’s Colours

Golden’s Intro to Varnishing

 

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