A Guide to Varnishes

Introduction To Varnish

What Is Varnish Used For?

Types Of Varnish

Choosing The Right Varnish

How To Apply Varnish

Making Your Own Varnish

Using Varnish Safely

Frequently Asked Questions

Further Reading

Glossary

A varnish is a coating of resin applied to the surface of a painting for protection and appearance. It helps to seal and preserve the painting by shielding it from dust, moisture, UV light, and physical damage. There is a range of varnishes to choose from with different characteristics, so it's important to choose the right one to ensure the best final results for your artwork.

Varnish has been used in various formats for thousands of years. The earliest versions were made by mixing resin, such as pine pitch, with a solvent. The technique is known to have been used in ancient Egypt and in East and South Asia, where lacquerwork traditions developed independently in India, China, and Japan.

This guide explores everything you need to know about art varnishes, from the different types and finishes available to how to apply them safely and effectively.

Varnish is a liquid coating applied to a painting once the paint is fully dry. It sits on top of the surface as a protective layer. Some varnishes can be removed later, which is important for cleaning or restoring the painting. 

Fixative is a spray applied to dry, powdery media, such as pastel and charcoal. These materials sit loosely on the surface and can smudge or be knocked more easily, so fixative helps secure the particles in place. A workable fixative can also be used to secure dry media and allow for further layering without smudging.

• Form and Application: Varnish is a liquid brushed or sprayed onto paintings. Fixative is always applied as a spray, directly onto dry media such as pastel or charcoal.
• Purpose: Varnish protects a finished painting from dust, moisture, and UV light. Fixative binds loose particles to the surface to stop them from smudging or transferring.
• Flexibility: Some varnishes can be removed later, which is useful for cleaning or restoring a painting. Fixatives come in two types: workable, which allows further layers to be added, and final, which is permanent.

Varnish forms a protective layer over the surface of an artwork, helping shield it from dust, dirt, moisture, and abrasion. Over time, unvarnished paintings can accumulate grime that is difficult to remove without damaging the paint layer. Varnish acts as a barrier, making the surface easier to clean and helping preserve the artwork for years to come. 

Many varnishes offer UV protection. This helps to slow the fading and yellowing of pigments when exposed to light. For works displayed in bright spaces, or where light exposure is a concern, a UV-resistant varnish can help slow fading and yellowing. It is still best to keep artworks away from direct sunlight.

Varnish can also unify the surface of a painting. Different areas of a painting can dry with different sheens; some passages may appear glossy, while others look dull or sunken. A coat of varnish evens out these inconsistencies, giving the work a consistent finish. Depending on the varnish chosen, this can be gloss, satin, or matt.

Some varnishes also help to deepen colour saturation. This is especially noticeable in oil paintings, where a gloss varnish can restore the luminosity of colours that have sunk in during drying.

It is worth noting the difference between removable and permanent varnishes. Removable varnishes, such as those based on dammar or synthetic resins, can be removed with a solvent at a later date. This is important for conservation. It allows the varnish layer to be cleaned or replaced without affecting the paint beneath.

Although some varnishes are described as removable, removing varnish from a valuable or important artwork is best left to a professional conservator. Solvents that dissolve varnish can also affect paint, especially if the wrong product was used or if the surface is fragile.

Permanent varnishes bond strongly to the surface and are not intended for removal. They are best suited to artworks that will not require future restoration, such as in crafts, decorative arts, murals, or artwork where long-term removability is not a concern.

There are many types of varnish available. Each one suits different media, surfaces, and needs. Some are made for oil painting, others for acrylics or dry media. Finishes range from gloss to satin to matt. Knowing all the options helps you pick the right product. It also helps you avoid common mistakes, like using a varnish that might damage the paint beneath, or applying a final varnish too early.

Varnishes tend to be grouped by the media they are made for, how they are applied, and how permanent they are. Here is a breakdown of the main types.

Varnishes for oil paintings are traditionally made from natural resins dissolved in a solvent. Dammar varnish is one of the most well-known. It dries to a clear, gloss finish and can be removed with mineral spirits, making it a good choice for artists who want a reversible option. However, dammar can yellow over time, which is worth bearing in mind for works with pale or cool palettes. Mastic varnish is another traditional option, though it is less commonly used today.

Gamblin Gamvar is a modern synthetic resin varnish for oil paintings. It was made in collaboration with the National Gallery of Art in the US. Gamvar is virtually odourless and ready to apply straight from the bottle. It will not yellow over time, which makes it a good choice for pale or cool palettes. It can be removed with Gamsol and comes in gloss, satin, and matt finishes. 

Gamvar varnish does not contain a UV stabiliser. Gamblin’s guidance is that artists should instead consider the lightfastness of the colours used in the painting. Colours with an ASTM Lightfastness rating of I or II are considered highly lightfast, while less lightfast colours may still fade over time if exposed to strong light. As with any artwork, paintings are best displayed away from direct sunlight.

Most acrylic varnishes are water-based and are easy to use. They work well when applied over acrylic paint and come in gloss, satin, and matt finishes. Most dry quickly and are flexible. They resist yellowing better than many oil-based options. Most can also be removed with the right solvent. Some are suitable for use over an oil painting once it has fully cured.

Aerosol varnishes are spray-applied. They offer even, consistent coverage in a range of finishes. They are a good choice for work with texture, such as mixed-media or heavily impastoed paintings, where a brush might not be able to get into small cracks. Spray varnishes are also useful for large works as they cover the surface quickly and evenly. Popular options include those from Lascaux, Krylon, Royal Talens, and Winsor & Newton.

Mineral spirit varnishes are solvent-based and most often used over oil paintings. They offer strong protection and a durable finish. Most come in gloss, satin, and matt options. They can also be removed with a solvent, such as turpentine.

Golden MSA Varnish with UVLS is a good option for artists who want a tougher, more durable finish. It also includes UV protection. Golden MSA Varnish can be used over acrylic, oil, and alkyd paintings, and can be removed with a solvent once dry, such as turpentine.

It is worth noting that MSA varnish needs more care in use. It is solvent-based, so it has a stronger smell than water-based varnish. Make sure you work in a well-ventilated space when applying it.

Watercolour varnishes are made for use over water-based media. Oil or acrylic varnishes can damage or reactivate watercolour, so it is important to use a product made for the purpose. Watercolour varnish protects the surface from dust and moisture, adding a clear, durable layer. It can also enhance the appearance of finished works.

That being said, most artists do not varnish watercolour paintings. This is because it can change their appearance and may disturb the paint or paper. A watercolour painting is usually framed behind glass, which protects it from dust, moisture, and touch. Since varnish can sink into the paper and be hard to remove, it may also make future repair or conservation more difficult.

To learn more, read our article ‘Watercolour Varnish: Can You Make Watercolour Waterproof?’ on Jackson's Artists' Blog.

Airbrush varnishes are thin and fluid, made for use through an airbrush. A fine, even coat is easy to achieve, making them ideal for illustration, model painting, and detailed fine art work. Our range includes popular options from Vallejo and Schmincke.

Lacquer dries to a hard, tough, and shiny finish. It has been used for thousands of years across East and South Asia, where lacquerwork traditions developed in China, Japan, and India. These traditions used lacquer to coat and decorate wood, metal, and other surfaces. 

Lacquer is most often used in decorative arts and crafts, and is less common in fine art. Unlike most artist varnishes, lacquer is permanent and is not meant to be removed. It is best suited to work where strong, lasting protection is the main goal.

Shellac is a natural resin secreted by the lac bug, found in India and Southeast Asia. It has been used as a wood finish and protective coating for centuries. It dries hard and is most common in decorative arts and woodworking. 

Shellac has a few other uses worth knowing. It seals absorbent surfaces before sizing, which is useful when preparing a surface for the application of metal leaf. It also protects gold and metal leaf once applied. Shellac can also be tinted with dry pigment to act as a glaze, adding warmth or colour to a surface. Finally, it can act as an isolating varnish, separating layers of media to prevent them from interacting.

Not all varnishes serve the same purpose. A retouching varnish is used by artists as a temporary protective layer on recently completed artwork, especially during the drying process. This makes it ideal for protecting a new painting that is going to be exhibited or sold. It can also be used to add a uniform sheen or correct dull or sunken-in areas. It is not a substitute for a final varnish.

Removable varnishes can be taken off with a solvent later. This leaves the paint layer beneath untouched, which is important for conservation and restoration. Removable varnishes are the best and most common option used by artists.

Permanent varnishes bond strongly to the surface and cannot be removed. They offer strong protection but should only be used where future restoration is not needed.

The finish of a varnish affects how light hits the surface. It shapes how viewers see the work.

A gloss finish reflects light strongly. It gives the surface a rich, wet look. It can deepen colour and restore the glow of oil paintings where colours have sunk in. Semi-gloss does the same but with less reflectivity. This helps reduce glare in bright spaces.

For artists who want to take gloss further, a hard resin coating can give an even shinier, wet-look finish. Read Varnish Your Painting With a Durable Wet-look Finish to find out more.

A satin finish sits between gloss and matt. It reduces glare while keeping some sheen. A satin finish works well in varied lighting. It reduces reflections without flattening the surface.

A matt finish absorbs light. It provides a soft, even surface where colour and composition take centre stage. Matt varnish can slightly reduce colour saturation.

Matt and satin varnishes contain matting agents that can dry cloudy, streaky, or patchy if applied too thickly, unevenly, or without thorough mixing. For the best clarity, many artists apply a gloss varnish first for protection, then finish with a satin or matt coat to achieve the desired sheen. Always test before applying to your finished work.

Many artist varnishes contain UV filters that help slow the fading and yellowing of colours caused by exposure to sunlight, keeping artworks looking vibrant for longer. The safest approach is to position artworks away from direct UV rays. You can also use UV-filtering acrylic or museum glass on framed pieces, which blocks a high amount of ultraviolet rays.

Varnish can change how colours look. Gloss tends to saturate most, then satin, then matt, but most varnishes saturate colours to some degree. Gloss varnishes tend to deepen and enrich colour. This suits oil painting well, but may not work for all media. Matt varnishes can reduce saturation slightly. Some traditional varnishes, such as dammar, yellow with age.

Fixative can also alter the appearance of dry media. This is most noticeable with pastel, where pale or delicate colours can darken or lose vibrancy. Always test on a small area or spare piece before varnishing or fixing a finished work.

Choosing the right varnish or fixative depends on the medium you are working with and where your artwork is in its journey. A painting that is freshly made needs different treatment from one that has been drying for months. This section covers the key things to consider before you apply anything to a finished work.

The sections above cover the most common painting and drawing media. Here is a brief guide to a few others that artists often ask about.

Traditional gouache can reactivate when it comes into contact with water. Most artists frame finished gouache works behind glass rather than varnishing them. If you do want to varnish, test carefully first.

Acrylic gouache behaves more like acrylic paint and is more tolerant of varnish, but it is still worth testing on a spare piece before applying to a finished work.

Dye-based inks and alcohol markers can be sensitive to sprays. Some fixatives and varnishes can cause colours to bleed, shift, or fade. Always test before applying to a finished piece. Pigment-based inks are generally more stable, but the same caution still applies.

Not all artist varnishes are suitable for inkjet or giclée prints. Standard varnishes can damage the surface or cause colours to shift. Use a varnish or coating specifically made for printed media. These are designed to protect the ink layer without disturbing it.

Some artists use a workable fixative to restore tooth between layers, allowing more colour to be built up. Wax-based coloured pencils can develop a faint haze on the surface over time, known as wax bloom. A light coat of fixative can help to reduce wax bloom on a finished piece. Always test first, as fixative can slightly alter the appearance of pale or delicate colours.

Shellac is a good choice for sealing and protecting metal leaf. It is worth noting that imitation leaf, which is made from copper alloy rather than real gold, can tarnish over time if left unsealed. A coat of shellac or suitable varnish helps prevent this. Genuine gold leaf does not tarnish and does not always need sealing, though a protective coat may still be applied for durability.

Varnishing an outdoor work presents different challenges from protecting a studio painting. Outdoor pieces are exposed to UV light, rain, pollution, temperature changes, and abrasion, so they require a tougher, more flexible varnish designed to withstand the elements. 

Flexible supports and exterior walls naturally expand and contract with changes in temperature and humidity. A rigid varnish can crack over time, so choose a flexible varnish formulated for outdoor or mural applications, such as Golden MSA Varnish with UVLS (quart size) or Golden MSA Mural Varnish with UVLS. Golden notes that gallon sizes of its standard MSA Varnish are not suitable for architectural applications, including murals painted directly onto walls and ceilings, so always check the manufacturer’s guidance before applying a coating to a wall or outdoor surface. 

Anti-graffiti coatings are a specialist category of their own. They are designed to allow graffiti to be removed without damaging the work beneath. These are not the same as picture varnishes and should be sourced from specialist suppliers.

It is also worth noting that removability and conservation priorities may differ for public or outdoor works. If the piece has long-term cultural significance, seek specialist advice before choosing a coating.

Not every artwork needs a varnish. Knowing when to use one, and when not to, is just as important as knowing which product to choose.

Varnish is most useful for oil and acrylic paintings that will be displayed without glass. It protects the surface from dust, moisture, and handling. It can also unify the sheen. For works framed behind glass, varnish is often not needed. The glass does much of the same job. Some artists still varnish before framing for extra protection, but it is not always necessary.

As mentioned in the 'Watercolour Varnish' section, watercolour paintings are usually framed behind glass rather than varnished. Watercolour varnishes can alter the appearance of the paint or sink into the paper. This can make future conservation difficult.

Drying time and curing time are not the same thing. An oil painting may feel dry to the touch long before it has fully cured. Oil paint needs ongoing access to oxygen as it hardens. Applying varnish too soon can prevent remaining solvents, moisture, or other volatile components from escaping properly from the paint layer. This can cause clouding, wrinkling, or poor adhesion.

For oil paintings, most manufacturers recommend waiting at least six months before varnishing. Paintings with thicker layers may need up to a year or longer. A retouching varnish can be used in the meantime to protect the surface or correct dull areas.

Acrylic paint dries much faster than oil paint. Most acrylic paintings can be varnished after a few weeks. You should always check the manufacturer's guidance for the specific product you are using.

Before varnishing an acrylic painting, many artists apply an isolation coat. An isolation coat is not the same as varnish. It is a thin, permanent layer of medium – usually a soft gel or gloss medium. Applied over the dry paint, it seals the surface and creates a barrier between the paint and a removable varnish. This makes it much safer to remove the varnish later without disturbing the paint beneath.

An isolation coat is also useful if you have used absorbent or matt grounds, as these can make varnish difficult to apply evenly. It also helps to even out any differences in sheen across the surface before varnishing. Because it is permanent, it should still be tested first.

Mixed media works can be tricky to varnish. Different materials in the same piece may respond in different ways to the same product. A varnish that works well on paint may damage paper, fabric, or other collage elements. Some materials can absorb varnish unevenly, leaving patchy results.

If you are working in mixed media, we recommend you test your varnish on each material separately before applying it to the whole piece. An aerosol varnish can be a safer option, as it is sprayed lightly on the surface rather than being worked in with a brush.

When choosing the best varnish for you, consider four things: drying time, removability, finish, and whether the work will be framed behind glass.

Removable varnishes are the best choice for most oil and acrylic paintings. They can be taken off and replaced as the work ages, which is important for conservation. Permanent varnishes offer strong protection but are very hard or impossible to remove. This is because they are designed to become part of the paint film, rather than remain a separate, soluble coating.

Some varnishes are not the most conservation-friendly choice. Traditional natural resin varnishes, such as dammar, can yellow and become harder to remove over time. Modern synthetic varnishes are generally more stable and easier to remove. They are the safer choice for work that you want to last.

Above all, always read the manufacturer's guidance before applying. This will ensure you avoid adding an irreversible coating without understanding the risks. If in doubt, you can seek advice from a conservator before varnishing a work of significant value.

Varnish is one part of preserving a finished artwork. Where and how you display and store a piece matters just as much.

• Avoid direct sunlight. UV light fades pigments over time, even in varnished works. No varnish offers complete UV protection.
• Avoid hanging above radiators, fireplaces, kitchens, or bathrooms. Heat, smoke, grease, and moisture can all damage paint and paper over time.
• Avoid high humidity and rapid temperature changes. These cause supports to expand and contract, which can lead to cracking or flaking over time.
• Keep works away from condensation. Exterior walls and unheated rooms can be problematic, particularly in older buildings.
• Dust frames carefully. Avoid wiping painted or dry media surfaces directly. Dust the frame only, and use a soft brush rather than a cloth.
• Use UV-filtering glazing where appropriate. Museum glass or UV-filtering acrylic blocks a high proportion of ultraviolet rays and is worth considering for works on paper or any piece displayed in a bright space.

Applying a varnish takes care and preparation. The steps below outline the key considerations before and during varnish application. 

For a complete guide on how to apply varnish, read our article How to Varnish a Painting in Oil, Water-Mixable Oil or Acrylic.

A good varnish brush is soft, flat, wide, and usually thin rather than thick. They usually have short handles as you apply the varnish with the brush held at a low angle. Jackson’s White Synthetic Mottlers are ideal for varnishing oil and acrylic paintings.

Keep a separate brush for varnishing and wash it right away after use. Keep it as soft and clean as you can. Dry the brush thoroughly before using it with oil varnishes.

Dust is one of the most common causes of a poor varnish finish. Any dust on the surface will get trapped under the varnish and become visible once it dries. 

Make sure to clean your surface well before you begin. Use a soft, lint-free cloth to wipe it down. For oil paintings, a light wipe with mineral spirits can help remove grease and residue. Make sure the surface is fully dry before you apply anything.

Your varnish brush needs to be clean, too. Brushes stored in open pots collect dust quickly. Rinse your brush before use and let it dry fully, especially if you are applying a solvent-based varnish.

Varnishing too soon is one of the most common mistakes. Paint that feels dry to the touch may not have fully cured. Applying varnish too early can trap volatile gases in the paint layer, leading to clouding, cracking, or poor adhesion.

For oil paintings, you should wait at least six months to a year before applying a final varnish. Thicker paintings may need longer. For acrylics, you should wait at least 72 hours, or 1-2 weeks or longer if you have used thick paint, gels, or a retarder.

Always test a new varnish before applying it to a finished work. Try it on a small corner or a spare piece first. Let it dry fully and check the finish in good light. This helps you spot any issues with sheen, coverage, or colour change before they affect the whole painting.

When applying varnish, do your best to work in a clean, dust-free space. You should varnish flat on a table where possible. You can also set up a lamp to shine light across the surface at a low angle. This raking light helps you spot missed areas and brushmarks as you work.

Make sure to apply your varnish in thin, even coats. A few thin coats are always better than one thick one. Thick varnish takes longer to dry, can pool in textured areas, and is more likely to crack or go cloudy.

Allow each coat to dry fully before applying the next. Finally, a helpful tip is to note the varnish you used on the back of the painting. This helps anyone who needs to clean or restore the work in the future.

For more information, read our article How to Varnish a Painting in Oil, Water-Mixable Oil or Acrylic.

Making your own varnish is a long-standing tradition. For centuries, artists and colourmakers prepared their own varnishes. These were most often made from natural resins dissolved in solvents. Before ready-made products were widely available, this was simply part of the process. Recipes were passed down through workshops and studios, and artists developed their own preferences for ratios and formulas.

The most common traditional varnish is dammar. This is a natural resin sourced from trees in Southeast Asia, especially species in the Dipterocarpaceae family. To make dammar varnish, the resin is dissolved in turpentine to make a clear, glossy liquid. It can be used as a final varnish, a glazing medium, or as an ingredient in other oil painting mediums. The process is quite simple and requires only a few basic materials.

For a full guide to making your own, read Vincent Gordon on How to Make Dammar Varnish on the Jackson's Artists' Blog.

Making your own varnish can be a useful exercise. It gives you a better understanding of what varnish is and how it works. It also connects you to a long history of craft and material knowledge.

That said, most artists today use ready-made products. Modern varnishes are consistent and reliable. They have been tested and refined to perform well across a wide range of conditions. Natural resin varnishes like dammar can yellow over time and may become harder to remove with age. Ready-made synthetic varnishes are generally more stable and easier to work with.

If you do choose to make your own, always work in a well-ventilated space. Turpentine and other solvents used in making varnish are flammable and should be handled with care. You can find out more in the safety section below, and our Guide to Studio Safety.

Varnishes contain solvents and other chemicals that need careful handling. There are a few simple rules that will keep you safe.

Always work in a well-ventilated space when applying varnish or fixative. This is the most important safety step. Solvent-based varnishes and most aerosol fixatives release fumes that are harmful to breathe. Open the windows and doors, or work outside where possible. If you are using spray products regularly, consider wearing a suitable respirator mask. A basic dust mask is not enough – you need one rated for organic vapours.

Water-based varnishes have lower fumes than solvent-based products. They are a safer choice for enclosed spaces or shared studios. That said, good ventilation is always recommended, regardless of the product you are using.

Solvent-based varnishes and fixatives are flammable. Keep them away from open flames, sparks, and heat sources. This includes candles, gas hobs, and electric heaters. Do not smoke near these products. Store them in a cool, dry place away from direct sunlight. Always replace lids and caps tightly after use.

Avoid breathing in fumes from solvent-based products. If you feel dizzy, have a headache, or feel unwell while working, stop and get some fresh air straight away.

Some varnishes and fixatives can irritate the skin. Wear gloves when handling solvent-based products. If any product comes into contact with your skin, wash it off quickly with soap and water. Keep products away from your eyes. If contact occurs, rinse with clean water and seek medical advice if needed.

Aerosol varnishes and fixatives should always be used outdoors or in a space with strong airflow. Never use aerosol sprays near a naked flame. The propellant in aerosol cans is flammable. Keep cans away from radiators, sunlight, and other heat sources.

Disposal rules vary by local authority. In many areas, completely empty aerosol cans can be recycled, but part-full cans may need to be taken to a recycling centre or treated as hazardous waste. Check your local council guidance if you are unsure. Never pierce, crush, flatten, heat, or incinerate an aerosol can, even when empty. 

• Read the manufacturer's safety guidance before using any new product.
• Keep all products out of reach of children and pets.
• Label containers clearly, especially if you decant products into other jars.
• Wash hands thoroughly after use.
• Keep food and drink out of the studio when working with solvents.

For more guidance on staying safe in the studio, visit our Guide to Studio Safety.

Varnish: Popular Questions from Artists

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

Watercolour Varnish: Can You Make Watercolour Waterproof?

Vincent Gordon on How to Make Dammar Varnish

Testing Natural Earth Paint’s Natural Varnish on Oil and Acrylic

Non-toxic Oil Painting Mediums and Oil Varnishes

Varnish Your Painting With a Durable Wet-look Finish

A

Adhesion
The ability of paint or medium to stick to a surface or to previous layers of paint. Good adhesion prevents flaking, peeling, or cracking over time. Adhesion can be improved with specific mediums, grounds, or primers. It is important when working on non-traditional surfaces such as metal, glass, or plastic.

Alkyd Resin
A synthetic resin made from modified plant oils, used in artists' paints, mediums, and varnishes. It dries to a tough, flexible, non-yellowing film and requires milder solvents than natural resins. 

Archival
A term used to describe materials that last a long time and resist damage. Archival panels, boards, and varnishes help to protect artwork.

C

Colour Strength/Saturation  
Colour strength essentially refers to the ratio of pigment to binder; it is a description of how vibrant/brilliant the colour appears. Saturation is another term used to define colour strength.

D

Dammar Resin
A natural tree resin that can be added to encaustic paint. It increases the hardness and colour vibrancy of the paint. It also improves its durability over time.

Dammar Varnish
A traditional natural resin gloss varnish used to protect oil paintings. It dries clear and is removable for conservation, although it may yellow with age.

F

Fixative
A spray used to protect and stabilise dry media, such as charcoal or pastel. Prevents smudging and fading.

Flammability
The tendency of a solvent to produce vapours that can ignite easily when exposed to heat, flames, or sparks.

G

Gloss
A surface that is shiny when dry is said to be gloss. Some oil paints appear more gloss than others, depending on the size of pigment particles and their concentration in the oil binder. Gloss can be increased by using a medium when painting.

L

Lacquer
A hard, durable, high-gloss coating traditionally used in Asian decorative arts. Unlike most artist varnishes, lacquer is permanent and is not intended to be removed.

Lightfastness/Permanence
Lightfastness or permanence indicates the degree to which a colour will fade or discolour as a result of exposure to natural sunlight. Paintmakers refer to either one of two scales designed to indicate the lightfastness of a colour – the American Society of Testing and Materials (ASTM) and the Blue Wool Scale (8 = most lightfast, 1 = least lightfast).

ASTM I = Excellent Lightfastness

ASTM II = Good lightfastness

ASTM III = Fair lightfastness

ASTM IV = Fugitive

M

Matt
A complete lack of shine on the surface, the opposite of gloss.

Mastic Varnish
A traditional natural resin varnish made from mastic resin dissolved in turpentine. It was a popular varnish for oil paintings in the 19th century. It may yellow with age.

O

Oxidation
The chemical process by which oil paint dries and hardens when exposed to air.

P

Permanent Varnish
Bonds permanently to the artwork and is intended for pieces where future removal is not required.

R

Resin
Dried, solid, or viscous sap or gum secreted by trees and plants (such as conifers and hardwoods). Varnishes can be prepared with natural resins such as dammar, mastic, copal, Venice turpentine, Canada balsam, Strasbourg turpentine (made from Silver Fir balsam), elemi, amber (historically), and others, by dissolving the resin in a strong solvent such as turpentine.

Retouching Varnish
A temporary varnish applied to a partially dry painting. Protects and allows for further painting.

Removable Varnish
Forms a protective layer that can be removed by a conservator for cleaning or future restoration.

S

Sheen
The measure of reflected light or glossiness from a dried surface finish. It is the primary factor that determines the visual lustre of an artwork, directly dictated by the type and concentration of the resin or binder used within the paint or medium.

Shellac
A natural resin secreted by the lac bug, found in India and Southeast Asia. It has been used as a wood finish and protective coating for centuries. It dries hard and is most common in decorative arts and woodworking.

Sinking In (oil painting)
When paint is absorbed by the surface it has been applied to, the colours appear less saturated than when they were first applied. This can sometimes cause some areas of the painting to appear shinier and more colour-filled than others. Often, there are inconsistencies in the absorbency of a surface, which affects the varying degrees of ‘sinking in’ on a surface.

Soluble
The ability of a substance to dissolve in a liquid. Acrylic paint is watersoluble when wet but waterproof when dry.

Solvent
A liquid used to thin oil paint or clean brushes. Examples include turpentine and white spirit.

Spray Varnish
A varnish applied from a spray can to protect finished paintings.

U

UV Protection Varnish
A varnish that protects paintings from the harmful effects of ultraviolet light.

V

Varnish
A protective coating applied to a finished painting to enhance its appearance and shield it from dust and damage.

Varnishing Brush
A varnishing brush is a clean, soft, square-ended brush, such as a synthetic mottler, designed to apply smooth, even coats of varnish with minimal brushmarks. 

W

White Spirit
A petroleum-based solvent. Used as an alternative to turpentine. For thinning paint and cleaning brushes.

Y

Yellowing
The natural process in which some oil paints and mediums darken over time due to oxidation.