Lustrous and versatile, oil paint has appealed to artists since the middle ages. Painters from Van Eyck to Hockney have been drawn to its rich sheen and vibrant colour. Oil paint consists of pigment dispersed in a drying oil, most commonly linseed oil. It is a comparatively slow drying paint which dries by absorbing oxygen from the air (a process called oxidisation). Drying rates depend on the thickness of the paint, the type of oil used, the pigments used, whether any driers or additives have been added to the paint, the absorbency of the surface it is applied to, the temperature, and the humidity.
NB: The term ‘drying’ is a bit of a misnomer. Oil paint hardens as the oil oxidises (a chemical reaction with air). This is different to watercolour, for example, where drying is caused by the water content evaporating.
For starters, a set of oil paints is a great investment as it’s a quick and easy way to acquire a selection of colours across the spectrum to explore. A limited palette of 4 or 5 colours actually has the potential to offer an extensive range of colours if you practice mixing varying quantities with one another. This can yield better results than working with hundreds of different tubes of colour, which will easily lead to muddy colour mixes.
You can start painting with the following materials:
The following tools are also useful, but not essential:
Oil paint, developed during the early Renaissance, has been the preferred painting medium of artists for hundreds of years. It is an extremely versatile medium, with a richness and vibrancy that is unparalleled.
How it looks: Generally oil paint dries with a satin sheen. The shininess, or finish of the paint when dry depends on how much pigment can be held by the oil. This in turn depends on the absorbency of the pigment particles, which varies from colour to colour. The highest quality professional oil colours will have the maximum possible amount of pigment ground into the oil. The impact of this is that the sheen may alter from colour to colour within a single range, but the colour vibrancy is unsurpassed. Many oil paint recipes used by the world’s finest paint-makers have hardly changed for hundreds of years, because there’s no need – the makers have perfected the recipe to such a degree, that the quality and handling properties are unmatched.
Versatility: Oil paint is extremely adaptable and can be manipulated extensively. Over the course of hundreds of years it has been used in an infinite number of ways. Just consider the layers of transparent luminous glazes to replicate the textures of skin, hair and clothing that you might see in a Rembrandt self-portrait, and then the explosion of colour and gesture associated with Willem de Kooning. The possible approaches to oil painting are limitless. Drying times can be reduced with cobalt or alkyd driers, paint can be thickened with sand, wax, or impasto mediums, and techniques such as blending, wiping away, and glazing can maximise the potential of your medium.
Read inspirational interviews on our blog with oil painters working today.
Making oil paint takes time. The article ‘The Secrets of Making Jackson’s Professional Oil Paint’ gives a comprehensive overview of the whole process.
To summarise, oil paint is made of pigment and drying oil. The quality of these two ingredients is instrumental in the quality and handling properties of the paint - the highest quality linseed oil will be clearer and less likely to colour yellow over time, while the highest quality pigments are free from impurities and will offer higher levels of colour saturation.
Traditionally, oil paint was made by hand in the artist’s studio using a muller and a glass slab, and although these recipes may not have changed, the manufacture has been made more efficient (making paints by hand is still considered better by some people): pigments are milled into the oil using a ‘triple roll mill’, made of steel or granite cylinders. Depending on the pigment, a machine will be selected with steel rolls or a granite mill to bring the best out of the ingredients and to avoid distressing some of the more temperamental colours. As a result tiny particles of pigment are suspended and equally dispersed in oil, at just the right proportions to allow light to bounce freely among the particles, releasing the greatest possible colour radiance.
Following this process, the paint is tested for quality before being put into metal tubes for distribution. A standard size is 37ml or 40ml, although some brands produce 60ml tubes as well, and larger tubes are usually around 200ml. Some brands produce 15ml tubes in introductory sets which are useful for carrying to paint outdoors.
The drying process of oil paint is different to other paints; acrylics and watercolours dry as their water content evaporates into the atmosphere, while the oil in oil paint reacts with air causing it to solidify – this process is called oxidisation. In the meantime the solvent in the paint evaporates. While the evaporation of the solvent doesn’t take very long at all, the oxidisation process is very slow and never really stops. As oil paint oxidises it first expands then contracts, but it is always larger than when it started because absorbing oxygen increases its size (unlike acrylic which loses water and shrinks by 45%). If anything that dries faster is put on top of not-sufficiently-dry oil paint it is likely to crack. This explains why oils can only be painted over acrylics but never the other way around, and why oils should always be painted fat over lean: the more oil (or fat) in the paint the longer it will take to dry. Always put paint with more oil over the top of paint that has less oil in it (more diluted with solvent).
A note about toxicity, and how to avoid solvents altogether to make oil painting a non-toxic process:
It is a common misconception that oil paints are highly toxic. In fact, oil paints do not emit heady fumes, and the majority are considered to have low toxicity. Some heavy metal pigments such as Cobalts, Cadmiums or Lead paints have higher toxicity and care should be exercised by handling with gloves if possible. Any strong fumes associated with oil painting come from solvents such as turpentine or white spirit, often used to thin oil paints or rinse brushes. However, solvents are not essential to the oil painting process and can be avoided. If you wish to clean your brushes without solvent it’s possible to loosen excess paint from your brush with a little vegetable oil, blotting as much as you can with a rag, and then rinsing as normal with brush soap.
Professional oil paints pack as much pigment into the oil as possible. Pigments are ground to a precise particle size that optimises the visual qualities of the colour, and then ground carefully into the drying oil binder. Occasionally the pigment to oil ratio is so great that the weight of the pigment sinks to the bottom of the tube, causing the binder and pigment to separate (this can be rectified by stirring the contents of the tube with a straightened paper clip). Milling the pigment to the optimal particle size allows the unique characteristics of the pigments to have a greater influence on the behaviour of the paint – properties such as sheen, transparency, tinting and staining capacity. These vary from colour to colour and contribute to the dynamism that can be achieved on your painting surface. Professional paints comprise a greater number of single pigment colours; colours look purer, more luminous and are easier to create vibrant mixes with, than tubes of colour containing multiple pigments. On the website paints that are classified as ‘Exceptional’ at jacksonsart.com are generally considered Professional quality.
Artist quality oil paints have a little less pigment in the mix but are usually made using very similar processes as professional paint. The characteristics of each pigment are maintained but with less intensity than the professional paints. Paints that are classified as ‘Excellent’, at jacksonsart.com are considered Artist quality.
Student quality oil paints have less pigment in them in order to keep production costs down, and may have added fillers to make the paints more uniform in tinting strength, viscosity and covering power. Driers are often added to slow drying pigments so that all colours dry at the same rate – the differing drying times of colours in professional and artist ranges can be a surprise for painters that have upgraded from student paints. Combinations of less expensive pigments are sometimes blended to replace the most expensive single pigment colours (these have the word ‘hue’ in their colour name). Colours may appear more chalky than Artist and Professional colours, and the choice is sometimes more limited and conventional. That said, they can be worth trying if you are new to oil painting and want to minimise how much you invest in your paints. Paints that are classified as ‘Good’ at jacksonsart.com are considered Student quality.
Traditional oil paints are made using finely ground pigment particles suspended in drying oils, usually linseed but sometimes pale colours are mixed with poppy, safflower or walnut. The buttery consistency can be made more fluid by moving the paint around with a palette knife once squeezed from the tube. The characteristics of oil paint - such as transparency, sheen, drying time and thickness - can be altered or enhanced by adding mediums; available ready to use or made by the artist from one or more drying oils, solvents and resins (alone, or in combination).
Water-mixable oil paints offer the charm of traditional oils with the added advantage of not requiring solvents for either thinning or the clean up operation. Water-mixable oils can be a little more stringy or fluid than regular oils, but for many, the advantages vastly outweigh the disadvantages; there is no need for the heady fumes of solvents, and it’s much safer and easier to clean up with soap and water. Special water-mixable oil painting mediums are also available. It’s possible to mix water-mixable oils with regular oils but in doing so they lose their water solubility.
Alkyd oil paints contain the same alkyd resin used in painting mediums to speed drying; a godsend for painters who have little time to spare. They handle in the same way as traditional oil paints and the alkyd paints can even be mixed with oil paint; this has the effect of speeding up the drying time of the oil paint, whilst retarding that of the alkyds'.
Oil Bars are also known as pigment sticks and are traditional oil paint mixed with just enough wax to allow it to form into a stick. They can be used directly onto a prepared surface; use them to draw straight onto canvas for example. Oil bars can be considered as either a drawing or painting medium; for a direct, tactile and expressive way of working. Marks can be thinned or made more fluid with solvent and oils, just like regular oils.
Oil paint can be used on its own, but many of the properties of the paint can be modified with the addition of different mediums. You can control the drying time (slower or faster), fluidity or thickness, sheen, transparency, and transparency can be increased, sheen altered, and paint can be thickened and made more fluid by adding different mediums. The majority of mediums are a blend of solvent with oil or alkyd resin, with some other ingredients such as beeswax or varnish added. Glaze mediums will allow you to create thin, transparent, gloss layers of paint, while beeswax mediums help to add bulk to paint for impasto techniques. Alkyd mediums will speed drying, so too will a drop of siccative added to your paint – this is a highly toxic cobalt based liquid that should be used very sparingly and with care. Many of the ingredients found in ready-mixed oil painting mediums are available on their own, so you can create your own oil painting mediums to perfectly suit your approach to painting.
Read our blog articles about making oil painting mediums:
A drying oil is a natural seed or nut oil that hardens by oxidation (absorption of oxygen from the air, which polymerises the oil into a durable paint film); it does not dry by a process of evaporation. It is combined with pigment to make oil paint, and added to oil painting mediums to help improve flow and increase transparency. Typically, a drying oil is mixed with other ingredients such as artists’ solvent, retouching or dammar varnish, or resin to create a painting medium that can improve flow, alter sheen, increase transparency, and alter the drying time.
When drying oils harden, their chemical and physical properties change, and the oil cannot revert to its liquid state by any means. The time it takes for a layer of drying oil to fully oxidise or cure is affected by how thick the layer is. It is advisable to apply thinner layers of oil to a painting beneath the thicker layers. The ‘fat over lean’ rule is a useful one to keep in mind; the rule suggests applying successive layers of paint that each have slightly more oil content, while ensuring that the layer underneath is touch dry before working over it. This avoids the risk of the upper layers drying more quickly than the layers beneath.
Arguably, the quickest way to remove excess paint from oil brushes at the end of a painting session is by rinsing them in solvent. Following this treatment, they would ideally be washed with a brush soap and warm water to complete the clean-up operation. Solvent can also be used to thin paint to a more watery consistency. The more you use, the more it will break down the oil content of your paint, so it’s worth being aware that very watery applications of dilute oil paint may not have sufficient binding properties, meaning the pigment could ‘wear off’ the painting surface in time, unless protected with a layer of varnish. Additionally, always ensure successive layers of paint have a greater oil content, so that the upper layers are always more flexible and slower drying than the paint in the layers beneath.
The traditional artist’s solvent is turpentine, a distillation of the resin extracted from pine tree sap. Cheap household turpentine is made from forest waste gathered from woodland ground and will contain impurities, which give an unpleasant smell, and make it less suitable for painting with; its exact contents is unknown, and likely to degrade a painted surface over time. Higher grades of turpentine are made from purer natural resin distillations, and will smell more pleasant as a result, although all turpentines should be used in a well ventilated space and may cause headaches with prolonged usage.
Artist white spirit is a petroleum distillation, and is suited to thinning oil paint. The heady fumes of turpentine or white spirit can be off-putting for some who are otherwise intrigued by oil painting, but these days you can work with a number of solvents that have little or no fragrance, and are less likely to give you a headache.
Pure-sol is one such example, a low odour solvent that is effective in cleaning brushes and thinning oil paint. Other examples include Gamsol, Sennelier Green Thinner and Zest-It.
Oil painting requires responsive brushes that are durable and hard-wearing enough to withstand the use of solvents, as well as contact with an abrasive surface (such as canvas or panel). It is worth investing in the best-quality brushes; they are always worth the extra expense as they hold the paint well, and if well cared for, will retain their shape and spring for far longer. Brush manufacture is a finely honed craft; a combination of carefully selecting the hair and materials to comprise the tuft, ferrule and handle. Hog hair brushes are particularly suitable for oil painting as they are hard-wearing and springy. Sable hair is softer for smoother, more detailed marks and synthetic hair brushes are a long-lasting, vegan alternative.
Many of the different types of brushes used for oil painting can also be used for painting with acrylic. Brushes such as hog and stiff synthetic can be used to move thick acrylic paint around the surface, whilst a soft brush can be used with fluid acrylic paint to create smooth marks.
There are some synthetic brushes that have been developed specifically to replicate natural hair. For example, the hairs of stiff synthetic brushes can replicate, and perform similarly to, the spring of natural hog hair bristles, whilst brushes with soft synthetic hair have been designed to replicate the performance of sable hair. Soft synthetic brushes are also a good alternative to sable brushes when a soft brush is required for oil painting, as they are more durable than sable hair. Brushes for oil painting also tend to have a longer handle, to enable the artist to stand back from the canvas or painting surface.
Watercolour brushes tend to have shorter handles and are made with softer hair than oil and acrylic brushes; this ensures the capability to hold lots of water or paint and release paint slowly and evenly upon contact with the paper surface.
It is advised to keep a separate collection of brushes for each medium, in order to preserve the life of the brushes, as well as to avoid contamination. No matter which medium, it is worth taking the time to clean and care for brushes to preserve their shape and spring for longer.
Hog brushes are often called the workhorse of an oil painter’s brush collection as they can cope with the thick, heavy texture of the paint, moving it around the surface, and enable application of thick dabs of colour. They are the most common and traditional type of brushes for oil painting and are made from hog bristles. They are hard-wearing and springy, which make them ideal for painting with oils as they can hold paint of a thicker consistency. They are also durable enough to withstand solvents. Hog brushes can be very versatile; they can be used for thin glazing effects as well as more impasto effects. The very finest hog brushes can be more expensive, but will retain both shape and spring for longer.
Sable brushes are suitable for detailed or subtle application of oil paint, allowing for glazing techniques without revealing obvious brush marks. Sable is very soft and less springy, allowing for fine, delicate details. They are not as hard-wearing as hog or synthetic, so may wear down quicker. Sable brushes for oil painting tend to have a long, sturdy handle to enable the artist to stand back from the canvas or painting surface.
Synthetic brushes come in a wide range, offering a vegan and economical alternative to natural hair. They are a good alternative to sable brushes when a soft brush is required for oil painting as they are more durable than sable hair. Stiffer synthetic brushes have also been developed to perform similarly to hog brushes, replicating the spring and suppleness of natural hog hair.
Brushes for oil painting come in a variety of sizes and shapes to suit different techniques and to enable different kinds of marks. Oil paints can be applied in thin washes, stains and glazes, as well as thick impasto marks, so it is useful to have an assortment of shapes and sizes depending on what marks are required. Oil painting brushes come in a range of sizes from 000 (the smallest) to around 16 (the largest), with a few manufacturers making very large brushes up to size 24. After a certain point, large flat brushes are called mottlers and their size is indicated by a measurement of their width. These sizes are not standard between manufacturers and are different for sable, synthetic and hog hair.
The most common shapes are flat, bright, round and filbert:
Flats are a good general purpose brush and are very versatile. They are useful for large washes and for painting-in large areas.
Brights have shorter, stiffer bristles than flats and are useful for applying heavier, impasto marks. They can leave strongly textured marks and because of their shorter bristle they are easier to control than flats, making them more useful for painting details.
Rounds can be used for fine details and strokes. They have good paint-holding capacity due to the ‘belly’ of the brush and are capable of holding thinly diluted paint for softer strokes, as well as thick paint for bolder marks.
Filberts are similar to the flats but have rounded corners and can produce soft, tapered strokes. They are also ideal for blending and the curved tip allows for a lot of control.
Other shapes include fan blenders, which are useful for blending colours, and riggers which have very long, flexible hairs.
It is ideal to have a selection of brushes to minimise cleaning whilst using different colours. It is good to start with at least two brushes, so that during a painting session you can use one for your lighter colours and one for your darks; this will prevent too much contamination between lights and darks. Medium to large brushes are ideal for covering large areas, but can also be used for detail. A useful selection of brushes to begin with could include the following:
Hog Brush - Round: size 2, 4, 6
Hog Brush - Flat: size 2, 4, 6
Hog Brush - Filbert: size 6, 10
Synthetic Soft Hair - Round: Size 4
A great way to start a collection of brushes is to invest in a brush set, such as one of these brush sets for oil painting.
Oil painting brushes should be thoroughly cleaned after each session. The lifespan of a brush will be prolonged if it is kept clean and cared for. If paint is trapped in the base of the hair, where it fits into the ferrule and is left to dry, the brush will become stiff and much less responsive. All brushes benefit from being cleaned with artist brush soap, as it helps to replace the natural oils in the hairs.
For more detailed advice on brush cleaning, have a look at our blog post Brush Cleaning with Jackson’s Marseille Soap.
Oil paints can be applied to canvas, paper, board or panels. Unlike any other artist paint, there is a risk of oils causing the natural fibres of a surface to rot if they are not properly sealed or sized before oil paints are applied to them. Additionally, if the oil from a deposit of paint does seep into natural fibres, it will leave the pigment sitting on the surface with no binder holding it in place, which can, over time, cause the colour to flake off, or create a yellow halo of oil around isolated brush marks. To avoid any of this happening it’s best to only apply oil paints to surfaces that have been sufficiently sized to protect them.
Acrylic or universally primed surfaces sometimes feel less smooth and more absorbent than oil primed surfaces. Some clear primed canvas panels may require another layer of clear primer added to ensure the surface is properly sealed – this will be stated in the product description online, but are perfect if you want to create the illusion of painting on raw canvas.
Oil painting papers are either made using a special additive which is blended into the pulp during manufacture to make the paper resistant to oil absorption (such as the paper made by Arches) and as a result are indistinguishable from other artist papers, or they are specially coated after sheet formation, or you can apply a sealant coat to paper yourself.
Boards and panels are either smooth, lightly textured or have primed canvas (cotton or linen) glued to their surface. They come either flat or cradled (with a support frame attached around the edges on the back). The wood on the back strengthens the panel and also allows the panel to be hung without framing. Uncradled, flat panels are slim for easy storage and transportation.
Stretched canvas can be lighter than board (when looking at sizes around 40 cm square and larger) and consist of a canvas made usually from linen or cotton duck that has been stretched tightly and evenly across a wooden frame. Stretched canvas is a responsive surface on which to paint; it is likely to bounce slightly as you apply pressure to it, which can contribute to the dynamism of a painting session.
Which surface you choose to paint on is entirely down to your preference, so ask yourself whether it’s important that your surface is lightweight, rigid, has texture or not, and so on. If you’re undecided I would recommend trying one each and seeing how each feels – the surface you paint on has a significant impact on the overall painting experience, and how your finished painting will look. What you choose to paint may dictate the kind of surface you decide to paint on.
An oil painting palette is usually made of glass, wood or plastic (although not all plastic palettes are suitable for oil painting), or you can use a disposable palette that comes in a pad of non-absorbent paper sheets called a tear-off palette. It is a non absorbent, smooth surface that provides an area for mixing colours.
A white palette can help to see how the paint will appear on a light coloured surface, which is why placing a white piece of paper underneath a glass slab can improve the visibility of your true colour mixes. Untreated wooden palettes tend to be very absorbent and will easily stain when used for the first few times. In order to minimise this happening you could varnish your wooden palette, or rub linseed oil into it, allowing it to dry fully before you use it. The absorbency of a palette reduces with use as it comes into contact with more and more drying oil.
Oil paints dry slowly in comparison to acrylics or watercolour, so in a lot of instances you can leave colour mixes on your palette to use the next day, however, they will start to dry after two or three days and once dry can be very hard to remove. To avoid this happening you can cover your paint in an airtight vessel, or add a drop of oil to the surface of a pool of colour in order to keep it workable for longer. You can choose a hand-held palette if you will be painting standing at the easel, or you use a palette on the table.
An easel is by no means essential. If you work standing up you could tape paper to a wall or hang your canvas or cradled panel from panel pins or screws. Alternatively you could work on the floor or prop your canvas up on a table. However, the right easel could allow you to move your work easily to better lighting conditions, or help you to work with a healthy posture, avoiding unnecessary aches and pains during a long painting session. When choosing an easel you have to ask yourself a set of questions.
Will you be painting at a table? If you will be, then a table easel is a compact device that will hold your canvas or paper upright. Many have a drawer in which you can store your paints and brushes. They are easy to store and transport.
Will you need to have a portable easel (perhaps for painting outdoors)? If you will be, then a sketching easel is what you’ll need. Sketching easels are usually made from aluminium or wood. An easy to carry sketching easel will be lightweight with telescopic legs allowing it to fold into a compact portable size. However if you are likely to paint in bracing wind conditions it may be at risk from falling over. Some string and tent pegs can be a great way to get around this.
Do you need an easel that will tilt to horizontal? (will you be painting with lots of dilute paint which might run?) Some studio and sketching easels will tilt fully to a horizontal working position, which can be really useful if you need to ensure your dilute paint applications do not run.
Do you need an easel that will hold very large work? The largest studio easels are H-frame and solidly stable for paintings up to 235 cm, but they will take up space and be heavy to move around. Crank handle easels make it easier to adjust the height of your painting.
A brush washer pot is designed to allow oil paint sediment accumulated from rinsing brushes to sink away to a different compartment, allowing you to get maximum usage from your solvent. Two Jackson’s brush washers have a spring holding system inbuilt, which holds your brushes so that they are suspended in the pot, rather than sitting on the bottom of it, which will bend the hairs of your brush and may damage them. A brush washer is not an essential, but it will help to prolong the lifespan of your brushes, help to keep your colours clean and bright and also help to get the most use from your solvent.
Palette knives are incredibly useful for oil painting. They can be used as an alternative to brushes, facilitating thick impasto applications of colour that can either be completely smooth or highly textured. They are also great for scraping wet paint away from your painting or palette, and mixing colours on your palette. In comparison to brushes they are much easier to remove paint from, one wipe on a rag and your knife will be clean for the next colour mix. They are available in a range of shapes and sizes, one or two in your armoury will significantly help keep your colour mixing organised.
You could use washing up liquid, but brush soap is especially formulated with natural oils to moisturise and cleanse brush hairs, so that your brushes keep their shape and hairs for longer. Without brush soap treatment, your brushes will prematurely begin to splay out, and may become caked with dried paint at the ferrule. Washing your brushes with brush soap and warm water after rinsing in solvent is an excellent habit to fall into, as you’ll be regularly moisturising the hairs which will prolong their lifespan as well as rinse away any residue solvent which would dry hairs out further.
Once you accidentally get a spot of highly staining Phthalo Blue on your clothes, it can be almost impossible to remove. An apron can protect your clothes and provide the peace of mind you need to focus on the more important aspects of the painting process. Deep pockets can help to ensure you have a pencil, eraser or measuring tape always within easy reach!
Finished paintings don’t necessarily have to be varnished, but a layer of varnish can enhance the depth and lustre of a painting, provide a consistent finish, as well as protect the surface from dust, humidity, and atmospheric pollutants. Ideally, artists' varnishes should be removable so that in the future if a painting is being restored, any cracked and stained varnish can be removed with solvents and replaced.
An oil painting should be completely dry before a final picture varnish is applied; this can take anything from six months to a year (or more, if it’s very thick paint). The surface of the painting will be touch dry much sooner (for very thin layers sometimes less than a week), and in this case, a thin layer of retouching varnish can be applied to protect the surface until it is completely dry.
Varnishes for oil painting are made from either natural or synthetic resin dissolved in a solvent such as turpentine. Synthetic resin varnishes, such as those made with alkyd and ketone dissolved in solvent, are modern versions of the traditional recipes and provide a tough and flexible finish.
There are two main types of varnish for oil painting:
Retouching Varnish is suitable for touch-dry paintings and can be applied before the paint is fully dried. It is more dilute than picture varnish and forms a thinner layer, allowing the oil paint to continue to dry over a longer period. It is fast drying and will unify the finish of the painting whilst protecting the surface. It will also give some protection if the painting is being exhibited before being fully dry. Application using a spray retouching varnish allows for a more uniform and consistent layer. Once the painting is fully dry, the surface can be cleaned of dust and a picture varnish can be applied over the top.
Picture Varnish is suitable only for fully dry paintings. Depending on the thickness of the paint, the support that the paint has been applied to and the atmosphere, an oil painting can take anything from six months to a number of years to be sufficiently dry for varnishing with picture varnish. It is less dilute than retouching varnish; containing more resin, and therefore, forming an inflexible and less porous layer. Picture varnish is naturally gloss—matting agents or beeswax are added to make matte picture varnish. Spray picture varnish is available for thin coats, otherwise the varnish is best applied with a brush.
1. A lint-free cloth can be used to remove any dust or dirt on the surface of the painting.
2. Apply the varnish in a well ventilated, dust free environment.
3. Ensure the painting is fully dry if applying picture varnish, (this can take anything from six months to a year or more, depending on the thickness of the paint) or if applying retouching varnish, ensure the painting is touch-dry.
4. Retouching varnish will leave a sheen and provide a consistent finish. Picture varnish is available in a gloss or matte finish (or a combination of the two to create a satin finish). Gloss will make colours lustrous and brilliant, but it can also be highly reflective and can show any bumps or unintentional texture. Matt varnish will need gently mixing before application, but the varnish must not have any bubbles in it when applied.
5. If applying the varnish with a brush, a good-quality, wide brush with either hog bristles or synthetic hair will reduce the possibility of brush marks. Apply the varnish quickly and gently in long, even strokes.
6. It is advisable to apply 2-3 thin layers of varnish, rather than one thick layer.
7. When applying the varnish, it is useful to position the painting under a light, so that it is easier to see the areas that have been varnished.
8. The painting should be left flat until the varnish is touch-dry. Once it is touch-dry, it can be leant against a wall with the front of the painting facing downwards. This will protect it from dust whilst it dries fully.
Artist quality varnish is removable and can be removed with solvent, but the same solvent will also remove the paint if not careful. Varnish should only be removed very gently and slowly (with a cotton-bud for example), and ideally by a professional restorer.