Watercolour Varnish: Can You Make Watercolour Waterproof? - Jackson's Art Blog (2024)

Historically, watercolour paintings have been displayed framed behind glass because they are on paper which can be stained by dirt and dust, can’t be cleaned with water and wrinkles with humidity. In addition, the watercolour paint itself is vulnerable to being re-dissolved with water. What if you wanted to paint a watercolour on a surface other than paper, one that is less sensitive to water like canvas – is there a way to make the watercolour paint permanent so it can be framed without glazing like an oil painting?

To clarify, it is not necessary to varnish a watercolour painting and varnishing is not usually done for traditional watercolour paintings. But there has been some interest lately 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.

Use Acrylics like Watercolour

One solution that can be successfully used is to paint with acrylic in washy, transparent layers or wet-into-wet, that looks like watercolour but is water-resistant when dry. (Some open-submission watercolour competitions allow acrylics painted in this manner.) The only real drawback is that, unlike watercolour, the paint won’t re-dissolve after it has dried, either in your work or on your palette. Though many painters take advantage of the re-dissolvability of watercolour paint to lift paint off the painting as part of their painting process, so for them it’s an important part of how they paint.

If you wish to use acrylics in the manner of a watercolour, be aware that a very dilute acrylic may not have enough binder to make the paint waterproof. You can remedy this by using a fluid acrylic or an acrylic ink (a very fluid acrylic) to ensure that you can get a washy consistency and still have enough binder for it to dry waterproof, because you won’t need to add as much water to create a wash. Using Airbrush Medium instead of water to make the paint more fluid without thinning it of acrylic binder, works very well. The very fluid acrylics are just as concentrated in colour as the heavy body paints but don’t have thickeners added, so you don’t need to dilute them as much to get a liquid wash. You may wish to add a flow release agent to the acrylic mixture or to the paper to allow even washes (it prevents beading up) and you may wish to apply a watercolour ground if you are painting on canvas (this will be more like painting on paper).

Use Aqua-Fix

Another solution is to use Schmincke Aqua-Fix, a liquid which when mixed with watercolour paint will make it dry water-resistant. This can also be useful for painting layers in any regular watercolour painting. Be aware that if you mix it with the paint in the pan the paint will harden and be ruined, so the idea is to use the Aqua-Fix instead of water on your brush and palette. It makes it a bit more like acrylic.

Use a Varnish or Fixative

Another option to make your watercolour painting less vulnerable to moisture is to use a varnish or fixative on the finished painting. I know that a brush-on, water-based varnish is not a good idea as it would smear the painting. But a spray-on fixative or a brush-on varnish that is not water-based will not re-wet the paint. I wanted to see which ones work best.

We have two products specifically for sealing watercolour: Schmincke Watercolour Fixative which is an aerosol and Daler-Rowney Watercolour Varnish which is a thick liquid applied with a brush. I wanted to see how well they work and if other solvent-based varnishes would work, also. Some artists use wax to seal their paintings so I wanted to try that as well.

I tested the following fixatives and varnishes in 1, 2 and 3 coats:

• Schmincke Watercolour Fixative (spray)
• Jackson’s Pastel Fixative (spray)
• Golden Archival Varnish Matt (spray)
• Daler-Rowney Watercolour Varnish (brush-on)
• Roberson Picture Varnish Matt (brush-on)
• Roberson Beeswax Picture Varnish (rub-on)
• Gamblin Cold Wax medium (rub-on)

These are the questions I wanted to answer:

• Do they disturb the paint when applied?
• Do they change the matt sheen of the painting?
• Do they darken or lighten the colours?
• How waterproof are they?
• How many coats do you need to apply to make it waterproof?
• Do they behave differently when applied to work on paper and to work on canvas that has a coating of absorbent ground?
• Daler-Rowney varnish is alcohol-based. What alcohol do you clean brushes with and can you thin it with that also?
• Is Schmincke Watercolour Fixative any different to a Pastel Fixative?
• Is Daler-Rowney Watercolour Varnish any different to a solvent-based varnish like Picture Varnish?
• Would a spray varnish that is solvent-based like Golden MSA Varnish work?

Some Things to Consider Before You Try This

There are a few things to be aware of when you are considering varnishing your watercolour painting.

• The addition of varnish to a watercolour painting will change the look and feel of the work, some more than others.
• The varnishing of a watercolour painting is a non-reversible process so as with all new techniques you are trying, practice it first on a test piece.
• You will not be able to add any more watercolour paint to the surface after it’s varnished.
• Because paper is highly absorbent, any varnish applied to the surface will soak into it and become a permanent, non-removable addition to the piece. This could re-categorise the watercolour as a mixed media piece and potentially exclude it from being considered a watercolour by some societies, museums, collectors, and conservators.
• You have a choice of sheens to consider. Some artists love the effect of a gloss varnish but others think that it begins to look like decoupage, and so they use a matt varnish which changes the look of the the original painting less.

Varnishing a Watercolour – the Testing Results

Skip to a summary of the test results.

The Test Charts

I made up charts with watercolour painted in two thicknesses – a diluted wash and two layers of thicker paint – in four colours, on two surfaces – Canson Moulin du Roi hotpress watercolour paper and Schmincke fine watercolour primer on a cotton canvas panel. I used Jackson’s Artist Watercolours in Phthalo Green Deep, French Ultramarine Light, Burnt Sienna and Cadmium Red.

I prepared the canvas surface with three light coats of Schmincke Aqua Primer fine, the last smoothed with a palette knife, on a Jackson’s Premium Cotton Canvas Art Board. I let it become touch dry between layers and let it cure for four days, but overnight should be enough. It was lovely to work on. It was very absorbent so the colours dried a bit lighter than on the paper, but it dried very evenly, without streaks and of course, it was a very flat surface without the need for paper stretching! You could see a hint of the canvas texture still and the surface felt slightly like smooth suede.

I then applied the fixative or varnish in columns of 0, 1, 2, 3 coats. When it was dry I ran a wet paintbrush over the colours trying to re-wet them. All colours with zero fixative re-wetted easily, though the watercolour painted onto the absorbent ground on canvas panel was harder to re-wet than those on watercolour paper. It was more absorbed into the surface and better adhered. This was especially true of the single light wash layers. As more layers of thicker paint were applied, the top layers of unvarnished watercolours were more re-wettable.

Since photographing sheen requires a tilting of the work to see it and in photographs it often looks like it is white rather than shiny, my description of the results may give more information than the photos.

In the results below I have grouped the seven varnishes into three groups: spray, brush-on and rub-on.

The Spray Varnishes and Fixatives

By applying a few coats these can be used alone or you can apply just one or two coats to stop smearing and then carefully brush on a water-based varnish.

A matt varnish creates the least change in the appearance of the painting. If you wish to apply a few coats of matt varnish it is best to begin with gloss in order to retain clarity and only use matt for the last coat. If you were to apply all the coats in matt the result could be a dusty look from the many layers of matting solids. The dusty lightening is most visible on dark colours, so you may also wish to use a gloss varnish on a dark painting and only use matt on a lighter painting.
For theses tests I sprayed the coats lightly and evenly from about 25cm distance.

Schmincke Watercolour Fixative (spray)

Fixing
To seal the paint from moisture more fixative is required on paint on paper than on the watercolour ground applied to canvas. On the treated canvas, a watercolour wash requires two coats for all the colours I tested, but that more thickly applied paint requires two coats for some of the colours I tested (Cadmium Red and Burnt Sienna) and three or even four coats for some of the colours I tested (Phthalo Green Deep, French Ultramarine Light). So it would make sense to use three or four coats across most paintings for complete fixing. On paper you need at least four coats for a heavier application of paint. Except for Phthalo Green which was a big problem, it wouldn’t fix on paper in a wash or thicker. I tried the same colour in another brand, Daniel Smith, and it had the same problem.

Surface Sheen and Colour Change
The surface became more glossy with each coating. Two coats is matt or satin depending on the colour of paint and three coats is satin to glossy depending on the colour of the paint. It did not darken or alter the colours in any application. Although Schmincke say that after a few coats the colours may darken, I did not find this to happen.

Jackson’s Pastel Fixative (spray)

Because pastel fixative is a matt, spray resin, basically a light varnish, I thought I’d add it to the testing.

Fixing
Two coats for most colours and 3 coats for phthalo green. So it would need three coats for most paintings. Same on both light and heavy applications of paint on paper.

Surface Sheen and Colour Change
No colour change. Each application made it a bit more glossy but in a speckled way, so it was more subtle.

Golden Archival MSA Varnish Matt (spray)

This is an extremely well-thought of varnish. But it has a strong odour that lingers, so you will want to spray it outside and let it air for at least a day before wrapping it up. And the solvent smell may still linger on the work.

Fixing
On absorbent ground it took one coat for the washy paint and two coats for the thicker paint. On paper it took one more coat for each.

Surface Sheen and Colour Change
On the washy paint on paper there was no change of colour or sheen. On the thick paint on paper all the colours except ultramarine became deeper, but the blue became lighter. There was very little change to the colour of the paint on the absorbent ground. There was no change to the sheen on either.

Shaking the Can
Spray varnish settles in the can and the nozzle tube reaches down to the thick stuff in the bottom. You need to shake it fully to incorporate the thick with the thin or it could come out in a spitting fashion and if it’s matt you will want to mix in the matting agent or the varnish will be glossy, or streaky. This means you need to shake it for a full two minutes. This can seem like ages, so pick a song or something or watch the video that Golden made to entertain you for two minutes while you shake your can.

The Brush-on Solvent Varnishes

These are mineral spirit or alcohol based so they won’t re-activate the dried watercolour like a water-based varnish would.

Daler-Rowney Watercolour Varnish (brush-on)

It has a mild, surgical spirits odour that goes away quickly. It is thick like honey and a bit hard to spread thinly. So I thinned it a bit with methylated spirits for the first coat. Coats two and three were not thinned. It is pretty fast-drying, if you keep brushing the varnish as it starts to dry it is a bit more matt, so I did that to the second coat. Then the third coat was applied quickly and without thinners and left to dry without disturbing it.

Fixing
Thinned, or brushed while it was drying, or applied thickly – all three methods worked to seal the watercolour with just one coat on both paper and on watercolour ground.

Surface Sheen and Colour Change
All three application methods darkened the colours on both paper and canvas, it was even more visible on the dark colours. The sheen was the thing that was affected by the application method. The thinned varnish and the brushed-while-drying varnish were less glossy, but not in a very even way. Applying it straight from the bottle gives a very glossy, wet-look finish.

Solvents for the Daler-Rowney Watercolour Varnish
I tested four alcohol-based fluids to see if they would work to thin the Daler-Rowney varnish and clean the brush after: Liquitex Pen Cleaner, Pinata Cleaner, Pinata Extender and Methylated spirits. The Liquitex didn’t work for this purpose, the others worked well. We don’t stock methylated spirits, as they now require a special licence, so you will need to purchase that from your local DIY shop if you wish to use it. The Pinata products come in very small bottles so if you can get a hold of the methylated spirits that would be the best choice. I also tested Gamsol, pretty sure it wouldn’t work and I was right. Oil paint solvents will not thin this varnish. Oil paint solvent will cause the varnish on your brush to turn gummy and will not clean the brush.

Roberson Picture Varnish Matt (brush-on)

Because it is matt you need to shake it fully to incorporate the matting agent or the varnish will be streaky. The matting agent used is microcrystalline wax.

Fixing
Two coats are required to seal the surface on both paper and canvas. The surface was slightly waxy and the water beaded up on it when I ran a wet brush over it.

Surface Sheen and Colour Change
I tested it twice and in one there was no change to the colour, in the second test the dark colours were significantly lightened, so I think I must have applied thicker coats. If you wish to keep your colours saturated then apply thin layers or as with other varnishes, only use matt as the final coat.
There was no change to sheen of the painting, it looked the same as unvarnished.

The Beeswax Varnishes

These two beeswax ones – the Roberson Beeswax varnish and Gamblin medium – are very similar. Their is a difference in the odour when applying – the Roberson smells like white spirit, the Gamblin doesn’t smell much at all. When the solvent has evaporated both leave the artwork smelling faintly of beeswax, it’s quite pleasant.

Neither of these products is described as a watercolour varnish and neither manufacturer mentions that you can use it on paper. But artists have been using these waxes and similar wax mediums to seal watercolours for at least the last eight years with no noticeable problems and it has become very popular in the last few years. Beeswax has been used as a painting medium and preservative for thousands of years. It is a stable and long-lasting finish on wood, canvas, paint and paper.

These varnishes are thick pastes and can be difficult to apply with a brush so are usually rubbed on like shoe polish. I have seen many artists using their finger to rub it on, but if you don’t want to get solvent on your bare skin you can use a lint-free cloth or gloves to apply the wax in a circular rubbing motion to cover the whole painting. I used a sandwich bag with my finger in the corner to rub it on. Wipe off any excess. 24 hours later when it is dry you can buff it with a lint-free cloth for a satin sheen. I waited an hour between each coat. For both brands the results showed that only one coat was needed to make the paint water-resistant. However when I buffed the single coat to give it a satin shine my cloth came away with colour on it. With two coats it did not. So it takes two coats to be fully sealed.

The only difference between these seems to be that the Gamblin stays a bit more tacky, even more so when it is buffed. It is an oil painting medium and perhaps has less resin than a product designed to be a varnish. A tacky surface is a drawback. The Roberson Beeswax was slightly tacky but not as much and when buffed went away almost entirely.

Roberson Beeswax Picture Varnish (rub-on)

The dried surface is not as sticky as the Gamblin, perhaps because it is designed for the purpose of varnishing. The instructions on the jar say that it may remain tacky if not polished. I found the unbuffed parts were slightly tacky, but far less tacky than the Gamblin. And after it was buffed it was not tacky, but it then had a satin sheen.

Fixing
Two coats are required for the paint to be fully sealed.

Surface Sheen and Colour Change
No change in colour and has a waxy matt finish unless you buff it and then it becomes satin.

Gamblin Cold Wax Medium (rub on)

The surface stays slightly tacky, even more so when it is buffed. It is an oil painting medium and perhaps has less resin than a product designed to be a varnish.

Fixing
Two coats are required for the paint to be fully sealed.

Surface Sheen and Colour Change
No change in colour and has a waxy matt finish unless you buff it and then it becomes satin.

Summary of Findings

Non-water-based varnishes and fixatives all work to make watercolour waterproof, whether they are mineral spirit or alcohol based, but some require more coats and some alter the sheen of the painting or the colour of the paint.

If you paint on a surface of primed wood or primed canvas that has three coats of watercolour ground (absorbent ground) applied then you are one step ahead because the paint it better adhered to the surface and requires one fewer coat of varnish than a painting on paper.

Sprays:
The sprays apply the thinnest layer so required at least three or four coats. Some colours were harder to seal than others. Some varnishes got more glossy with more coats. Some lightened the colour with more coats of matt.

Brush-on:
The brush-on varnishes worked very well. The Daler-Rowney alcohol-based varnish was very glossy. Since they are all similar to the Roberson’s picture varnish, any oil painting picture varnish should work – if you want it matt then choose a matt picture varnish.

Rub-on wax varnishes:
The rub-on wax varnishes and mediums worked very well. They only made a small change to the artwork, only needed two coats, and were low odour. Some are a bit tacky and some need to be buffed the next day to remove any tackiness. Other brands should work just as well as the ones tested here.

Mounting a Sealed Watercolour Painting onto a Wooden Panel

Framing works on paper behind glass works well for most artists, but unless you use museum glass there is the problem of reflections and if you paint large watercolours it can be expensive or difficult to frame them. While nothing protects a watercolour painting on paper as well as being properly framed, can it be treated so it could be displayed without a frame?

If you wish to seal your watercolour painting on paper and then mount it onto a panel, this blog post about mounting canvas onto panel will help as the technique is the same.
Making a Canvas Painting Panel. The only difference will be centering the finished artwork on the panel. If you need to crop the paper a bit, do it leaving a few millimetres evenly all around, lay it face down on the table, place the panel with adhesive facing down on top insuring you have the same amount of paper all round. Then when you have smoothed it, weighted it and it is dry, you can trim the edges even with a knife.

Try your first one with a less precious artwork and see if you like the effect.

Longevity

All of these products have a good longevity (sometimes called being archival) when used with oil and acrylic on canvas and paper. There should be no difference when used with watercolour. They are artist-quality materials and when the solvents have evaporated you are left with just resin or wax. Some are specifically labelled for use with watercolour, but they are all sound for use with watercolour.

Further Reading

Watercolour Grounds: Painting with Watercolour on Canvas

Preparing Circular Painting Panels

Making Beeswax Impasto Medium for Oil Painting

Tips for Setting Up an Oil Painting Palette

Materials

• Schmincke Watercolour Fixative
• Jackson’s Pastel Fixative
• Golden Archival Varnish Matt
• Golden Archival Varnish Gloss
• Daler-Rowney Watercolour Varnish
• Roberson Picture Varnish Matt
• Roberson Beeswax Picture Varnish
• Gamblin Cold Wax medium
• Michael Harding Matt Varnish
• Pinata Cleaner and Extender
• Moulin du Roi Watercolour Paper
• Jackson’s Premium Cotton Canvas Art Boards
• Schmincke Aqua Primer
• All Watercolour Grounds
• Jackson’s Artist Watercolours
• Acrylic Inks
• Airbrush Medium
• Acrylic Flow Release
• Schmincke Aqua-Fix
• Disposable Nitrile Gloves
• Smooth Wooden Painting Panels
• Snap Knives