Varnishing Acrylic Paintings

Varnishing Acrylic Paintings

What you need to know before varnishing acrylic paintings?

There are many considerations you need to make before embarking on your creative journey, such as subject matter, techniques, personal style, scale, what substrate we use to paint onto, your audience or client and where the painting will be exhibited to name just a few. There are also many stages during that creative journey that the painting goes through before we are satisfied that our artistic voice has been realised. Being in the creative zone takes time, energy, prior knowledge and the right preparation does go a long way to achieving the results we want. The first few paragraphs will highlight a common mistake some may make whilst working with acrylic paint, namely, using too much water - we look at why this is a problem, outline the options you have, and what processes are needed before the very last stage of your work can be approached which is 'varnishing'.

To begin with, a short overview of acrylic paint and why we shouldn't use too much water!

Acrylic paint is a hard wearing and quick drying water-based painting medium with endless possibilities in terms of application. Water based means that water is a very small part of the ingredient which makes an emulsion, together with an acrylic polymer binder and pigment particles.
This small amount of water in the paint mixture is crucial and aids the drying process; when it evaporates, it pulls the pigment particles and binder together forming a close bond and a thin film on the surface first. The milled pigment particles are basically suspended in the paint emulsion until it is applied onto the substrate and until it dries. The pigment does not dissolve, it becomes trapped in the binder on whatever surface you paint onto. Acrylic paint will dry to a resilient finish and have a strong adhesion to the substrate if it has not been under-bound by over diluting.

Acrylic paint is also water-soluble, meaning it can be diluted with a very small amount of water as a solvent to extend the paint. However, the emphasis is on a small amount of water to dilute, you should never use more than 20% to 25% water to acrylic paint ratio, if diluted too much this will result in under-binding and change the integrity of the paint when dry. The acrylic polymer binder and pigment particles become too far apart whilst drying and they can not form a strong bond, this could result in your acrylic painting peeling or flaking. To prevent this, instead of using water alone, use an acrylic polymer wetting solution to dilute or thin the pigment to your desired consistency. Winsor & Newton make a professional acrylic medium flow improver that increases flow and maintains stability, once dry the paint becomes permanent and water-insoluble. There are many options regarding changing the viscosity of the acrylic paint depending on your own personal style of work.

Acrylic paint is also produced in varying viscosities, such as heavy body, soft body, and fluid acrylic for pouring (acrylic inks and acrylic paint markers are also available).

Why Acrylic paintings should be completely dry before varnishing.

Depending on the application used, for example thick or thin impasto or flat levelling acrylic pours, acrylic paintings must be completely dry on the surface and be fully cured underneath before varnishing. This will prevent the colour lifting or any inadvertent flattening of surface peaks if you have created a more three dimensional surface.

When drying, acrylic paint forms a thin slightly flexible skin or film, it appears to be dry on top very quickly. In reality, the paint underneath will take much longer to cure, days, weeks or even months, especially when the paint has been thickly applied or has been mixed with acrylic mediums which extend the drying time; An example of acrylic mediums would be molding paste, Golden soft gel medium, textured mediums, Winsor & Newton Professional Acrylic Slow Drying Medium, Glazing mediums etc...

It also makes a difference where the acrylic painting is placed whilst drying. For best results, aim to put your painting in a dust and humid free environment, this will aid the drying time.

Once dry, the painting will appear waterproof and impenetrable. However, it is actually only water-resistant, not fully waterproof and will remain slightly porous without a varnish layer being applied. If you had a microscope, you would see that the surface of the painting has tiny pin holes and crevices, where, in some cases the bond between the pigment and acrylic polymer emulsion has not created a solid bond or a solid film. This actually means the surface of the painting could be potentially receptive and hold onto dust, dirt, airborne chemicals, and moisture which are harmful.

Why do we need to varnish acrylic paintings and what are the advantages of varnishing?

A varnished acrylic painting will have greater longevity, as varnishing will protect the surface from permanent damage from a number of airborne pollutants including dust, smoke and steam. It also protects from UV rays, (which could fade fugitive pigments), extremes of temperature, humidity, from being damaged/scratched during transportation, or from oils after being handled.

Varnishing also provides either a satin, matte, or gloss sheen to the surface of your artwork, unifying the surface and enhancing the colours. Sometimes paintings only finally come together when varnished, especially when some areas of the painting have dried matte and some areas have dried glossy. This happens when water dilution has not been consistent or when different glazing mediums have been used.

What Varnish should I use?

Whilst there are many varnishes out there on the market (and it can become very confusing), when buying varnish for acrylic paintings, your first priority would be to decide on what finish would best compliment your work; matte, satin or gloss varnish?

Creating some test examples of acrylic varnish finishes would be beneficial before committing to your beloved acrylic painting. Investigating which varnish finish is most suitable would also help you to rehearse the application process whilst deciding on the final surface aesthetic.

Aim to create a striped image with the same paints and palette you have used on your painting. Create the stripes wide enough so when you apply the varnishes over all the colours you will clearly see their distinctive finishes and you can identify any colour shifts or variations in colour saturation.

Monitor how long your painted samples take to dry completely, then add an isolation coat (only if you are going to use a removable varnish). Again monitor how long this takes to dry, then go about investigating the different varnishes. This sample will act as your go-to aid for all future paintings.

A Matte finish is non reflective as it suggests, gloss can be very reflective under interior or natural light and satin provides a soft sheen; also consider that colours can change dramatically after the varnish has been applied, some will darken whilst others will become more vibrant.

What is an Isolation/Barrier Coat?

Before varnishing your painting and if you are using a removable varnish, it is advisable to apply an isolation coat first. The isolation coat has a glossy and transparent finish and will provide a level base on which to varnish onto. This permanent protective barrier seals all of the porous surface and will protect your painting if you ever need to remove or replace the layers of varnish above it. Varnish removal will involve using a solvent, which could damage the actual painting below if you do not create a permanent protective barrier. Using a gloss isolation coat, especially before applying a matte or satin varnish, will prevent a cloudy appearance from occurring in the varnish layer.

Because this barrier is a permanent layer on your acrylic painting, it is advised that you create a series of investigations to ensure your isolation coat application is compatible with your aspirations. Whichever isolation product you use, ensure you read the instructions carefully, different brands will have different instructions. Some may need diluting and some can be used straight out of the bottle.

When using Golden Soft Gel Gloss as an isolation coat, use 2 parts Soft Gel Gloss 1 part water. Wheras, Golden's Isolation Coat medium, for example does not need diluting.

Most isolation coat brands can be used on canvas, wooden panel or paper.

Isolation Coat brands

Isolation Layers

How to apply an isolation coat to acrylic paintings step by step .

  • Your painting must be compeletely dry before application of an isolation coat. (no less than 72 hours and leave up to several months if you can)
  • Create a dust free and clean space in your studio.
  • Dust your painting with a clean soft brush or lint-free cloth, to dislodge any dust particles.
  • Have all your equipment at hand, clean and ready to use.
  • Check your soft synthetic brushes are clean and pigment free. It is easier to keep a dedicated isolation brush specifically for this process.
  • Choose a soft, wide, flat brush to ensure a flat finish without any brush marks.
  • Work flat on a stable table surface when applying an isolation coat with a brush.
  • If you are painting the sides of a canvas or panel, you will need to elevate your work on blocks so you don't touch the working table, this will prevent picking up any debris with your brush that may be then transferred onto your work and prevent your work sticking to the table.
  • Before applying your isolation coat rehearse your brush strokes! Yes this sounds strange, but this will help you in the long run as you need to work quickly.
  • Before applying your isolation coat give it a gentle stir. Do not create any bubbles. Check manufacturers instructions, some isolation coats need to be diluted.
  • Decant your isolation coat into a flat shallow dish for easy access, one that fits your brush width.
  • Dip your brush into the fluid but avoid overloading it, remove excess fluid from your brush on the sides of your dish.
  • Apply the isolation coat with consistent long brush strokes, working from one side to the other, don't stop and start half way across your painting, and don't reapply the isolation coat to any areas you may have missed, work relatively quickly. Try not to create any air bubbles.
  • Three thin layers will work better than one very thick coat.
  • If possible shield the work from dust and flying bugs with a tent like screen, then do not move until dry.
  • Let each layer dry fully, at least 24 hours, before applying the next.

Solvent-based or water-based acrylic varnish?

Another consideration before you purchase will be whether or not you want to use a solvent-based MSA (mineral spirit acrylic) varnish or a water-based polymer one. Both contain UV filters and will protect your painting, however, the MSA varnish can be used for both oil paintings and acrylic paintings, it is clear on application and will dry to a harder finish; Liquitex makes a varnish called Soluvar which is archival and removable for acrylic and oil paintings. Golden also make an MSA varnish in Matte, Satin and Gloss. If you choose to use an MSA varnish you will need to use a mineral spirit solvent for removal. When using solvent based varnishes you will need to wear a NIOSH approved respirator for protection as the fumes are toxic; your brushes will also need to be cleaned with a mineral spirit solvent. Solvent resistant gloves and protective clothing are also recommended.

A water-based varnish however is a non-toxic option and brushes can be cleaned with just soap and water; no harmful fumes and safer for the environment. Both Golden, Winsor & Newton, Daler Rowney and Liquitex make acrylic polymer water-based varnish in either a liquid or gel consistency. Some of these varnishes can appear white or semi-translucent on application. They do dry clear and transparent but the matte varnishes can lighten dark areas of the painting due to the matting agent.

Acrylic polymer varnish can also be removed with low odour solvent or turpentine.

Removable or permanent acrylic varnish?

A removable varnish will allow you to clean your painting and re-apply the varnish in the future. At this point if you wish, you may change the paintings surface appearance say from a matte varnish to a gloss or satin finish (once the original varnish has been completely removed). You must apply an isolation coat if you are going to remove your varnish so the underlying paint layer isn't damaged. The removable varnishes are just as protective as the permanent ones.

A permanent varnish does not require an isolation coat as it cannot be removed but should provide an archival level of protection. Removable and permanent varnishes come in both aerosol and liquid.

Spray Varnish Brands removable and non-removable. 

Non-removable 'permanent' finish.

Liquitex aerosol varnish Liquitex Professional Varnish Spray

Spray varnish

What it does

  • 100% acrylic polymer varnish adds a satin sheen, protects and resists dirt retention
  • Dries clear to a flexible, non-tacky, hard surface
  • Increases brightness and colour saturation
  • Adjusts and unifies surface sheen
  • Improves surface durability - ideal when shipping or exhibiting
  • Protects colours from UV light damage
  • Resists discolouration - yellowing and fogging - caused by humidity, heat and UV
  • Depending on the substrate it allows surface moisture to pass through and breathe
  • Allows for easy cleaning without fear of damaging the acrylic paint film
  • Has excellent levelling properties - will not hold brush marks
  • Semi-opaque when wet, transparent when dry
  • Use on flexible or rigid supports
  • Ideal for complete coverage of heavy textures and vertical applications
  • Designed for interior and exterior use

How to use it

  • As this is permanent, do a patch test first
  • Before varnishing ensure paint surface is fully dry (72 hours-two weeks depending on thickness)
  • Ensure your space is well ventilated and dirt and dust-free
  • Place the artwork flat on a surface - always varnish horizontally
  • Use long, even strokes, covering the surface top to bottom while moving from one side to the other - don't go over bits you have missed, but leave to dry and then re-varnish area
  • Apply 1-2 thin coats, allowing at least three hours dry time between coats
  • If you require more than two layers, first use Gloss Varnish as a base layer and build to your desired thickness, then apply Satin Varnish as your top coat

How not to use it

  • Don't apply in one thick coat, but several thin coats, to avoid drips and cloudiness
  • Don't go back over areas you have already done, as this can cause clouding
  • Don't attempt to remove once applied
  • Do not use with any non-acrylic media

Montana aerosol Varnish (Permanent).

Acid-free, quick drying, clear varnish made of acrylic base. No yellowing or de-saturation. For interior and exterior use. Can be used for art, hobby, crafts and DIY. Available in gloss, semi-gloss, matte finish. Gloss level shown on donut (see top of can). Protects and fixes paint on surfaces like canvas, paper, charcoal drawing, bast fibre, wood, photos, etc. Protects against oxidation. During application, protect the object and the surrounding area from spray. Surfaces should be dry, clean of dust, oils and rust before applying the varnish.

Shake can well for 2-3 minutes upside down to take advantage of gravity. Remove the safety ring by removing the nozzle and turning the can upside down allowing it to fall out. Then re-apply the nozzle. Apply varnish in several thin layers, spraying before the previous coat is fully dry but with 2 minutes between each pass. Further coats might require a drying time of 24 hours or more depending on substrate. For optimal lifespan, always store cans with the nozzle on. NOT COMPATIBLE WITH SYNTHETIC BASE LACQUERS. Always test spray on a non-visible area to check compatibility of lacquer or paint.

Removable aerosol varnishes:

Winsor & Newton varnishes.

All Winsor & Newton varnishes can be used on oil, alkyd, water mixable oil or acrylic paintings. Professional Acrylic Gloss, Matt or Satin Varnishes: These varnishes are uniquely formulated to be removable and contain UV resistance. The Satin Varnish gives a mid-sheen finish, in between the Matt and Gloss Varnish finishes. The Galeria Acrylic range also has its own collection of gloss, matt and satin varnishes.

Pebeo Acrylic aerosol Varnish

The acrylic colours have great qualities of resistance to aging, the varnishing makes it possible to further improve these qualities, to unify the differences in brightness of the painting and to increase the depth of the colours. When the colour is applied in great thickness, wait 1 to 2 weeks before varnishing the work. Non-yellowing and remarkably transparent. Filling, it gives after application a perfectly stretched, flexible and indelible film, as well as a very uniform shine. Can be diluted with water. Solvent-based acrylic varnishes have the particularity of guaranteeing the possibility of restoration of the work. They are available in: - glossy: perfectly transparent, matt: rather opalescent, and satin.

Non-yellowing, particularly transparent. Perfectly stretched, flexible and indelible thermoplastic film allowing the restoration of the work. Very uniform glossy finish. Suitable for: Adult, Student, Beginner amateur, Confirmed amateur.

Ghiant Acrylic aerosol Varnish

Ghiant H2O Water Based Varnishes give the same results as traditional aerosol-spray varnishes, but have 90% fewer solvents and 35% fewer VOCs than normal aerosol sprays. Ghiant H2O Varnishes are UV-resistant, acid-free, and will not yellow or discolour. Suitable for the protection of oil and acrylic paintings.

Frisk Varnish Aerosol

Frisk Varnish is a water-based varnish with 90% less solvents that will protect acrylic and oil paintings from dust and moister with a non yellowing protective coating and is UV resistant. Finely dispersed, will not soak through or wrinkle light materials. Perfect for all art and craft projects.

Environmentally friendly, CFC free, ideal for use in the studio, office or home.

Loxley Picture Aerosol Varnish Removable

  • Professional, solvent based varnish
  • Protects from paintings from atmospheric decay
  • Satin finish (semi-gloss)
  • Archival; allows for future removal/restoration by art restorers
  • Large 400ml can


Liquid Varnish brands

Winsor & Newton Professional Acrylic UV liquid Varnish for Acrylic Paintings.

This varnish protects your art from airborne pollutants, UV damage and fading. It dries to an even finish. It can be removed with Artists' Acrylic Varnish Remover. Choose from, Gloss, Matt or Satin. It can be applies by soft bristle brush or airbrush with some dilution. Apply in thin layers, allowing each to dry completely in between to avoid frosting.

Water-based varnishes can be cleaned up while wet using soap and water and removed from brushes or paintings when dry with Galeria Varnish Remover.

Golden Polymer liquid Varnish and aerosol.

GOLDEN Polymer Varnish with UVLS (Ultra Violet Light Stabilisers) is a water-based acrylic polymer varnish formulated to provide additional protection from ultraviolet radiation. This helps delay the inevitable fading that occurs in materials that may be fugitive in nature.

Polymer Varnish is designed as a topcoat for acrylic paints and offers a removable protective surface to the relatively soft acrylic paint layer. It has a harder film than most acrylic paints, which diminishes the susceptibility of the surface to dust and dirt, and provides increased protection from scratching, marring and moisture. It has adequate flexibility to withstand normal handling conditions, including loose rolling. Do not use for oil paintings. For interior use only. The product is not recommended for use on furniture or other surfaces subject to physical contact during use.

Polymer Varnish remains soluble in alkaline solvents, such as ammonia. This means the varnish can be easily removed; taking with it any accumulated surface contamination without damaging the painting surface. The use of such a removable varnish provides a valuable tool to anyone trying to restore or clean a painting.

Polymer Varnish (Gloss) dries to a highly reflective finish. Polymer Varnish (Satin) offers moderate reflection, similar to most matte varnishes. The Matte is exceptionally flat. The different finishes can be intermixed, or used sequentially, to achieve the desired sheen. Note: Polymer Varnish (Satin) and (Matte) will lighten dark value colours, which is typical of non-gloss varnishes.

Liquitex Removable Varnish Soluvar

Liquitex Soluvar Matt Varnish lowers intensity and depth of colour, while reducing the surface glare when applied as a final varnish over dry acrylic or oil paint. It is a permanent, removable, final varnish for acrylic and oil paintings that protects the painting surface and allows for removal of surface dirt, without damaging the painting underneath.

Once the painting surface is clean, a new coat of Soluvar Matt Varnish may be reapplied to surface. It is self-levelling varnish so will not hold brush strokes.

Soluvar Matt Varnish dries extremely clear and is a durable archival quality varnish that is non-yellowing. This varnish dries to a non-tacky, hard, flexible surface with a water resistant finish.

Remove and thin with up to 25% of mineral spirits or turpentine. Do not use Odourless Mineral Spirits.

This product is suitable for interior and exterior use. Also available in Soluvar Gloss Varnish which may be intermixed for a variety of sheens.

Liquitex Professional liquid Varnish Non-removable

Liquitex archival 100% acrylic polymer varnish are non-removable, adds a satin sheen, protects and resists dirt retention. Dries clear to a flexible, non-tacky, hard surface. Increases brightness and colour saturation. Adjusts and unifies surface sheen. Improves surface durability - ideal when shipping or exhibiting. Protects colours from UV light damage. Resists discoloration - yellowing and fogging - caused by humidity, heat and UV. Depending on the substrate it allows surface moisture to pass through and breathe. Allows for easy cleaning without fear of damaging the acrylic paint film. Has excellent levelling properties - will not hold brush marks. Semi-opaque when wet, transparent when dry. Use on flexible or rigid supports. Designed for interior and exterior use.

Additional equipment to aid varnishing

Additional equipment to aid varnishing

 

How to varnish your acrylic painting, step by step tips.

How to apply liquid varnish. (Apply isolation coat first if using removable varnish)

  • Firstly your artwork must be completely dry. Leave for at least 7 days up to 4 months.
  • Always give yourself plenty of space in a dust free studio.
  • Only varnish in a well ventilated environment, if using spray aerosol varnish, always wear the correct protective face mask (not a home-made one), protective clothing and gloves.
  • Dust your painting with a clean soft brush or lint-free cloth, to dislodge any dust particles.
  • Have all your equipment at hand clean and ready to use.
  • Check your soft synthetic brushes are clean and pigment free. It is easier to keep a dedicated varnish brush specifically for this process.
  • Choose a soft, wide, flat brush to ensure a flat finish without any brush marks.
  • Work flat on a stable table, when applying a liquid varnish with a brush.
  • If you are varnishing the sides of a canvas or panel, you will need to elevate your work on blocks so you don't touch the working table, this will prevent picking up any debris with your brush that may be then transferred onto your work and prevent your work sticking to the table.
  • Before applying your varnish rehearse your brush strokes! Yes, this sounds strange but this will help you in the long run as you'll need to work quickly.
  • Before applying your varnish give it a gentle stir. Do not create any air bubbles.
  • Decant your varnish into a flat shallow dish for easy access, one that fits your brush width.
  • Dip your brush into the varnish but avoid overloading it with varnish, remove excess varnish from your brush on the sides of your dish.
  • Apply the varnish with consistent long brush strokes, working from one side to the other, don't stop and start half way across your painting, and don't reapply varnish to any areas you may have missed, work relatively quickly. Try not to create bubbles in the varnish.
  • Three thin layers will work better than a very thick coat of varnish.
  • If possible, shield the work from dust and flying bugs with a tent like screen then do not move.
  • Let each layer dry fully, at least 24 hours, before applying the next.

How to apply Aerosol spray varnish

  • Follow all the guidance above regarding prepping your materials, equipment and environment.
  • Instead of laying your painting down on the table, hang it vertically or lean it upright against a wall in front of a card which is bigger than your painting to protect your wall.
  • Read the instructions on your spray varnish thoroughly, brands may vary.
  • Shake your spray varnish for the recommended time.
  • Practise spraying without actually spraying, move consistently and without stopping.
  • Practise spraying your paint onto a piece of cardboard to free up your nozzle from blockages and to get a feel of the speed in which the varnish is released.
  • This is important as you can easily leave an unnecessary build up of varnish drips on your painting if you do not move smoothly and consistently.
  • When you are ready, hold the spray at least 6 to 12 inches away from your work, spray to the side of your work first then whilst holding the nozzle down move across from edge to edge, try not to overlap the spray to avoid drips.
  • Work quickly, leave to dry before applying a second and third coat. Wait 24 hours but read instructions as each brand may be different.

Ellie Jakeman
Ellie Jakeman

I have had a strong interest in the visual and creative arts since a very early age. I completed with great success ‘A’ level Fine Art, Textile and Embroidery City and Guilds, Foundation Diploma in Fine Art, (BA hons) Degree in Embroidery and Textiles from Manchester Metropolitan University and a PGCE from the University of Huddersfield. I have taught Art and Design, Fashion and Textiles, Textile design and Fine Art print and Illustration for over 20 years. I have also instigated and program managed many projects for the local community. Before teaching I was a freelance artist and illustrator and decided 4 years ago I would return to freelance and commissioned work. I have created many domestic and commercial murals for hospitals and hospices. I work part time for Artdiscount as a content creator and product tester.


1 Response

Stuart Roper
Stuart Roper

July 05, 2021

Really interesting article and it’s good to get more detailed information on the various brands of Varnish. Thanks very much.

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