Oil Painting Mediums

Oil Painting Mediums: A Guide

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Oil painting mediums can be used to alter the consistency, transparency, finish or drying time of the paint. They also extend the paint, meaning a little paint can go much further.

There are many different types of mediums you can use with oil paint, so read on to understand the properties of each and how you can combine them with your paint to get the best results.

Why use a medium?

When the paint isn’t doing what you want it to, there will be a medium you can use to modify the paint to make it easier to work with.

Used straight from the tube, oil paints can be unpredictable. Drying times and viscosity vary between colours (even if they are from the same range of paints that you bought together). So mediums can be used to level these out.

All mediums have their own unique properties—so many effects can be achieved depending on which medium you choose to mix into your paint. You can thicken the paint, thin the paint, give it matte or gloss finish, soften the paint, level out the brush strokes, or give your paint more body and texture.

By becoming more informed about the specific properties of different mediums, artists can harness these properties to achieve the desired effects in their art.

So if you want more predictable, consistent results and to level out the drying times of your paints, just add a little medium…

Solvents

Prussian Blue and Scarlet Lake pigments straight from the tube, and mixed with distilled turpentine on oil sketching pad.

Properties: thins paint, increases transparency, increases flow, speeds drying time, gives paint a matte finish.

Solvents are what you use to clean your equipment after painting, but they can also be worked into your painting. They stand as a vital part of the painting process for many artists.

When mixed with your paints, the solvent will evaporate from the surface of the painting (taking around a day to dry), leaving the pigment and oil binder to oxidise.

Solvents change the finish of the paint, they make the colours duller, dryer and more brittle. So it’s suitable to use them to thin the paint to block in large areas of colour in the first stages of the painting which won’t necessarily be seen in the finished piece.

Excessive use of solvents can create a chalky effect in your painting, and painting with solvent-thinned-paint over very oil rich layers will likely cause the paint film to crack (to prevent this from happening, learn the fat-over-lean rule).

If you’re not sure where to start in using solvents to create your own medium, it’s good practice to start blocking in colours with purely pigment and solvent, then work up to a 1:2 oil to solvent mixture, then 1:1 and gradually increasing the amount of oil in your mixtures for each new layer. That is the fat over lean rule in short.

If you want to make your own painting medium, add either cold pressed linseed oil, or linseed stand oil to the solvent. The oil needs to be added to the solvent, not the other way around, as linseed oil is viscous, so it requires agitation to mix properly. Leave your mixture to sit for 48 hours so it combines.

Turpentine

Buy turpentine here.

Called ‘Turps’ for short, turpentine is distilled from the resin of pine trees, and has a very fast evaporation rate.

Of all the solvents, turpentine is probably the most compatible with oil paint. When mixed with the oil and pigment in the paint, the pigments will be dispersed perfectly, giving an even finish.

Just make sure you get the refined artist grade stuff, as cheaper turpentine that can be bought in hardware stores generally has more impurities that shouldn’t be incorporated into paintings. Undistilled decorator’s turpentine contains gum residue which can cause yellowing.

Bear in mind that turpentine is a toxic chemical, its vapour is also toxic so it is harmful to breath it in. The fumes can get heady.

If you choose to use turpentine as a medium, it’s best to use it in a space that’s very well ventilated and away from children and pets. Always keep the toxic chemicals in lidded jars so you’re not breathing in fumes unnecessarily and always wear protective rubber gloves if you think your skin might come into contact with it.

There are clever ways of purifying the air in your space—like filling it with house plants.

As turpentine is the most widely used of all solvents for oil painting, it is generally considered a benchmark, that the effectiveness of other solvents are compared against.

Turpentine has a considerable active strength, it can be reused time and time again. Just wait for sedimentation to occur and simply filter the solvent from the paint particles at the bottom.

If you’re feeling completely put off at the thought of painting with solvents, it’s perfectly doable to cut solvents out of your painting process completely. There are plenty of alternatives to turpentine too, alternatives that are much less toxic, read on to find out…

Odourless mineral spirits (artist’s white spirit)

Buy odourless mineral spirit here.

In the UK, we call it white spirit, but in the US it’s referred to as odourless mineral spirits (OMS). White spirit is a petroleum distillate that can also be used for thinning oil colours.

It’s not as compatible with the paint as turpentine, as it is more abrasive and will break the paint down in a more uncontrollable way. It is advised to mix with another oil medium if using to thin paint.

White spirit dries at a slower rate and gives a more watery mixture than turpentine. It comes in odourless varieties, which is a more refined distillate—it’s less harmful but still toxic.

Don’t bother getting the decorator grade white spirit if you’re using it as a medium and incorporating it into your painting. The best odourless mineral spirit to use in your studio would be Gamblin’s formulation called Gamsol, as the aromatic solvents have been refined from it, so that less than 0.005% remain.

Bear in mind that OMS can cause embrittlement as it weakens the paint film. The finish is much better with turpentine. OMS can be used as a medium, but it’s pretty effective to use as a brush cleaner, as it’s cheaper than turpentine.

Oil of spike lavender

Buy oil of spike lavender here.

This solvent was historically used as an alternative to turpentine. It is strong enough to fully dissolve resins, and mixes very well with oil to create mediums. It breaks down thicker paint with ease.

Oil of spike lavender is actually a stronger solvent than turpentine, so less is needed to effectively thin paint. It works to improve the clarity in your painting, extend uniform particle dispersion and increases adhesion of oil paint layers.

The solvent is far less toxic than turpentine; it does have strong fumes, but many people agree that the aroma is more pleasant. As it is a solvent, it should be used the same way as turpentine, with good ventilation and by avoiding contact with the eyes and skin.

This solvent is much more expensive than turpentine, but a little goes a very long way, you’ll only need to use a drop or two at a time.

Zest-it®

Buy Zest-it here.

This is also described as a safer alternative to turpentine and works as an effective replacement. It doesn’t contain any aromatic hydrocarbons or CFCs.

It’s also kinder to the environment than turpentine as it is biodegradable.

It thins oil paint, cleans brushes and can dilute resin to create varnish. It’s not as effective at thinning when compared with turpentine or oil of spike lavender, however. Your mixtures will be thicker and it can make paint cloudy.

Oils

Properties: increases transparency, increases flow, slows drying time, levels brush strokes, creates a ‘fatter’ paint layer.

Not all types of oil can be used in oil painting.

The most commonly used oils that can be used in painting are linseed oil (and all its variations), safflower oil, poppy seed oil and walnut oil.

These oils all share one common attribute, they are all siccative. They undergo a polymerisation process, whereby the molecules in the oil combine with molecules in the air to form a solid layer. It’s due to their ability to oxidise that these oils get their name ‘drying oils’.

Other drying oils include perilla, soybean and tung. These are less widely used for various reasons. Perilla is very prone to yellowing as it cures, soybean and tung do not make for very permeable paint films.

All oils are considered ‘fat’ so thinking of the fat over lean rule, you would gradually add tiny amounts of oil to your paint, or increase the ratio in your mixed mediums as you add to the layers in your painting.

Refined linseed oil

Buy refined linseed oil here.

This is obtained from the dried, ripened seeds of the flax plant. So you might also see linseed oil being sold as flax oil or even flaxseed oil.

This is the most widely used oil to mix with solvents and oil paints to create mediums, this is due to the fact that it has an unmatchable durability when compared to other drying oils.

It acts to reduce the oil viscosity, slow the drying time, and increase the gloss of the oil paint.

Linseed oil is slightly yellow in colour and it should be noted that using linseed oil can cause your paint to yellow over time.

Linseed oil contains both linolenic and linoleic acid in measures that is favourable to oil painters. Linolenic acid is the component in the oil that causes yellowing, but also creates a durable paint film. So any oil with a high linoleic content will produce a strong film.

Cold-pressed linseed oil

Buy cold-pressed linseed oil here.

Get cold pressed linseed oil (mixed with oil of spike lavender) to use as a lean medium here.

This helps to create a shinier and harder finish to your paint film when compared to that of refined linseed oil. It also dries slower than refined linseed oil, taking around four days to become touch dry.

The oil is very high quality, and is often used as the oil binder, in which pigments are ground in many professional paints. It is considered a good choice for a binder due to its high acid number, which coats the pigments more effectively than oils with low acid numbers.

Linseed stand oil

Buy stand oil here.

Often referred to as ‘stand oil’ or ‘bodied oil’—this thick oil derives from flax, much the same as regular linseed oil.

The difference lies in the treatment of the oil. Refined linseed oil is heated at a high temperature often in a vacuum sealed chamber to make bodied oil.

Stand oil is much more concentrated, meaning a little bit goes a long way and the consistency is much thicker, almost like honey.

When considering its handling properties, It leaves a glossy finish, which makes this medium great for glazing.

Another great thing about stand oil is that it is less prone to yellowing than linseed oil. The fact that the oil has been heated means that it has undergone polymerisation, meaning that it is already part-way to being a dried film. This means that the paint has less oxidation to do before it dries; oxidation being the main culprit of a yellowed paint film.

Stand oil has good flowing properties, but not as good as linseed oil. You might feel more of a ‘drag’ on your paint brush when using stand oil, the oil has great brush levelling properties however.

If you mix stand oil with turpentine, you can make a medium that dries slightly quicker than linseed oil mixed with turpentine.

Stand oil is less prone to a phenomenon called ‘sinking in’, whereby the oil in a layer of paint is absorbed into the layer below causing dulled out areas in the painting. This is because the molecules in stand oil are larger, meaning that they’re not easily absorbed by porous materials.

Safflower oil

Buy safflower oil here.

Safflower oil used as an alternative binder by paint manufacturers with lighter colours and whites, as it contains next to no linolenic fatty acid (the main component in linseed oil which causes paints to yellow).

As it solely contains linoleic acid, which many will argue that when used by itself is a weaker binder.

When used as an oil painting medium, Safflower oil increases the flow and has a lower viscosity than linseed oil, which means that it will make the paint spread further. You can see from the image above, that the safflower + oil paint mixture was the runniest.

It has other beneficial properties, namely that the paint film is less likely to wrinkle over time than linseed oil.

Safflower oil is a lot cheaper than linseed oil. It dries a lot slower, and actually doesn’t ever fully cure. If left in extremely hot temperatures, there have been cases of paint actually melting. It has a much weaker paint film than linseed oil.

Some will advise against using this as a painting medium, but it works fine when used sparingly. For example, when applied thinly on the top layers of your painting if you wanted to mix it with light colours. Of course, negative properties of your materials can always be counterbalanced and controlled with good practice, so as long as you are aware that the paint will dry with a weaker film. For example, you could paint a layer of varnish over the top to seal the paint.

Poppy seed oil

Buy poppy seed oil here.

Poppy oil, or Poppy Seed Oil is similar to safflower oil in the sense that it is a clear oil medium which doesn’t alter the colour of your paint, and is less prone to discolouration over time.

Poppy seed oil was found to be used as a binder by Monet in his painting Water-Lilies, which would explain how the painting has maintained its sharp blue-violet hues over the years.

It’s one of the more expensive drying oils you can buy. Artist-grade paint manufacturer Blockx uses poppy oil as a binder in all of their paints. You can read more about that in this paint brand review.

It’s slower drying than linseed oil, and safflower oil and it enhances the gloss and flow of your paint.

Poppy oil contains hardly any of the fatty acid I mentioned earlier, linolenic acid, which is the main component that makes a super durable film when the paint cures. As a result, your paint film will be a tad softer when you use poppy seed oil, compared to if you used linseed. You can counteract this by using it in conjunction with a small amount of linseed oil though.

Walnut oil

Buy walnut oil here.

Walnut oil is a great alternative to linseed oil. It is less prone to yellowing and creates a more flexible and durable paint film than poppy and safflower oil.

Examples of paint manufacturers that use Walnut Oil as a binder, are M. Graham and Blue Ridge.

Walnut oil can be mixed into paint in the same way as other oil-based media. It can also be used to clean brushes. If you are wanting to keep your space solvent-free, this is a good alternative to remove paint from your tools.

The medium is very glossy and hard-wearing, and gives colours depth. The oil is also very slippery, it improves the flow of the paint and slows drying times.

A good tip is to keep walnut oil in the refrigerator. It can go rancid if left at room temperature and especially if left in direct sunlight.

All oils go rancid when exposed to air. This isn’t noticeable with linseed oil which is only used in small quantities in paint. However, nut oils can go rancid in the bottle if it’s not sealed and stored properly.

One good use of walnut oil, is to ‘oil out’ a painting. Where a painting has become dry in areas, the oil content has sunk in to bottom layers of the painting. Spreading a thin layer of walnut oil over the painting can restore its brightness.

Cold wax

Properties: thickens paint, gives a matte finish, textured brushstrokes, speeds drying time.

This medium comes in a thick paste. When added to your oil paint, you can create body, volume and retain brushstrokes.

The medium actually has a whole style of painting associated with it—cold-wax painting. Think of heavily textured works with thick, expressionistic impasto brush strokes and luscious matte finishes. If you don’t want your painting to appear matted, you can always add alkyd to give it a little sheen. You’d get an almost satin-like effect.

You can add another dimension to your painting by using wax, building layer upon layer to create structure. The cold wax adds luminosity and transparency to your paint too. You really can be quite generous with the ratio of wax to paint, though it could be recommended to use ⅓ cold wax to ⅔ oil, if you want a textured impasto effect. You could even add dry pigment to the wax, and not add any oil whatsoever, but if you do this add a little alkyd to prevent paint layers from cracking.

Painting with wax is pretty straight forward, as the ‘fat over lean’ rule used by oil painters to prevent adverse effects like cracking, does not apply. Also it speeds up drying time, so your painting will be dry in a couple of days, even if you’ve painted in very thick layers.

All wax used in conjunction with oil paint is called ‘cold-wax’ because the wax does not require heat to dry to its final form (as in encaustic painting).

A combination of beeswax, resin, solvents and sometimes linseed oil are the ingredients used to make the medium; as the solvent evaporates, the soft wax hardens.

Gamblin, Zest-it and Michael Harding all produce their own answers to cold-wax mediums. They all have slightly different formulations and therefore different characteristics:

Gamblin cold wax

Get it here.

Made from natural white beeswax, Gamsol (Gamblin’s own solvent), and a small amount of damar. The medium has a ‘short’ characteristic. This means that when you pull your palette knife away, the wax stays on the canvas, almost like it has broken at your stroke. You can achieve very sharp points and textured impasto strokes with this medium. The wax has a melting point of 68 degrees Celsius, so your painting won’t melt even on the hottest day of the year.

Zest-it cold wax

Get it here.

Made with beeswax, linseed oil and damar. It is designed to be used with their Zest-it wax solvent (a non-flammable solvent made from citrus zest).

Michael Harding beeswax paste

Get it here.

This one is made with high-grade pure bleached beeswax which adds flexibility. It’s also made with viscous linseed stand oil, chosen for its elasticity and stability.

Michael Harding resin oil wax medium

Get it here.

This resin can be used to create a softer impasto effect. It is a liquid medium made from bleached beeswax, dammar resin and viscous linseed stand oil.

Alkyd resin

Properties: adds body to paint, gives a glossy finish, speeds drying time

Alkyd is synthetic resin, usually derived from oil to create a fast drying medium. Alkyds made by different manufacturers are usually a combination of highly polymerised plant-based oil (such as soy) and slow-evaporating odourless mineral spirits.

Alkyd mediums mixed with oil should dry in around 24 hours. If you’re an artist who likes to work quickly, and can’t fathom waiting for up to a week for oil paint to dry, then it might be worth considering incorporating alkyd into your painting process.

Another attractive property of alkyd, is that it will make your paint stretch much further across the canvas. This is without making it too runny or transparent.

Alkyd creates a flexible, firm and glossy surface, which in some cases is almost glass-like.

The ‘fat over lean’ rule doesn’t apply to alkyds, as alkyds aren’t oil, you can’t consider them to be either ‘fat’ or ‘lean’. However, the general rule of thumb is that alkyds should be treated as the ‘fat’. So you slowly increase the amount of alkyd added to your paint in consecutive layers. Alkyds make the paint film more flexible. A good way to look at layering with alkyds is that you should layer flexible over less flexible.

You can of course thin alkyds, they don’t require a powerful thinner like turpentine. It’s perfectly fine to use OMS.

Another thing to note is that you may get undesired results from your oil painting if you interchange layering oil and alkyd. You can use them in conjunction, but if you’ve chosen to use an alkyd, stick with that through each layer of the painting.

Walnut alkyd medium

Get it here.

M. Graham’s alkyd is derived from walnut oil. It has a similar consistency to stand oil and is completely solvent-free.

It will increase flow, transparency but dry much faster than the non-alkyd walnut oil alternative.

Liquin Original

Get it here.

Get Liquin Fine Detail (a thinner more fluid version of the original) here.

Liquin is an alkyd formulated by Winsor & Newton. It halves drying time of paint, due to the cobalt drier it contains. If you were to leave your paints out over night, they would be stiff by the next day.

It levels brushstrokes and increases the flow of the paint. Although the mixture looks brown in the bottle, it doesn’t discolour the paint in any way and actually resists yellowing.

Liquin works best when it’s used as a medium without the addition of extra drying oils such as linseed or stand.

Galkyd

Get it here.

Galkyd has much the same properties as the alkyd mediums above, it increases flow and transparency. When you use a lot of it, it will also level brush strokes and give a hard, enamel-like finish to your work.

Gamblin also supply solvent free alkyd mediums.

Liquin Impasto Medium

Buy it here.

This comes out of the tube like a gel, and like Liquin original, it’s not prone to yellowing.

The thick gel adds body to your paint, enabling you to create textured impasto works with thick brushstrokes.

The finish is advertised as being satin-like, but I find it to be quite glossy.

Neo Megilp

Buy it here.

This alkyd is described to be a contemporary version of the Flemish all-in-one medium Maroger. The consistency is like a jelly. It acts as a versatile medium that provides a durable and silken finish to oil paintings. However, it doesn’t yellow like Maroger is famed for doing.

Found your favourite oil painting mediums?

Exploring and experimenting with different mediums will lead you to find something you truly love working with. It will make your painting process more enjoyable too.

Oil painting mediums are great for making paint more workable, but their main pull is the way they can make an artist’s paintings stand out. By using a unique combination of mediums, techniques and subject matter you can create a style that’s recognisably yours.

Finally

If you’re just beginning on your oil painting journey and you’re not quite sure what supplies to get, start with this beginner’s guide. It’ll teach you about all the tools and materials you need to start oil painting and give you valuable advice on how to use the materials to get the best results.

If you want to stock up on oil painting supplies, check out our art shop.

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