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PAINTBOX ART SUPPLIES GUIDE: OIL PAINTING MEDIUMS

OIL PAINTING MEDIUMS & SOLVENTS

This Oil Painting Mediums Guide aims to give a broad overview of some useful and interesting information about working in this medium. Oil paint is a special medium that gives beautiful results. With a bit of understanding of the structure, the best way to use it, how to modify your colour with oil mediums, and the options available you will be able to get the most from the time-honoured medium of oil painting. If you have any further questions please ask them by submitting a comment, underneath the post.

A drying oil is a natural oil that oxidises when exposed to air, causing it to contract and harden into a solid layer. Linseed oil is the most common drying oil used in oil paint manufacture; however Poppy, Walnut, Safflower and Lavender Spike oils are all used as well. Each oil brings its own characteristics to the personality of the paint.

Refined Linseed Oil

  • Popular and traditional oil made from seeds of flax plant, used to make mediums for oil painting
  • Increases gloss and transparency
  • Dries solidly, throughout the oil film, making it very stable and permanent
  • Ideal for underpainting/initial layers in a painting
  • Dries within 3-5 days
  • Very pale light yellow in colour, may have slight colour influence on whites/pale colours
  • Alkali refined – impurities have been removed to minimise the yellowing of the oil over time
  • Mix with solvents in equal measure (or more oil than solvent depending on your preference) to make a versatile oil painting medium which flows and dries glossy

Alkali Refined Safflower Oil

  • Pale coloured alkali refined oil with little tendency to yellow
  • Favoured for use with whites and blues
  • Longer drying time than linseed oil

Stand Oil

  • Paler, more viscous oil than refined linseed oil
  • Slows drying
  • Gives tough elastic finish
  • Mix with turps or white spirit to help colour flow and reduce brush marks
  • Is made by heating without air at very high temperatures. This partly polymerises the oil, making thicker in consistency yet maintaining a smoothness that allows it to level brush marks and be the ideal component in a glaze medium. Also its viscosity means one can use it to paint using impasto techniques knowing that the paint will not wrinkle and it will dry in a more stable manner than when just applying the colour thicker or with more regular linseed oil added to it. It yellows less than refined linseed oil and is also slower drying.

Walnut Oil

  • Very pale yellow brown oil
  • Excellent resistance to yellowing and cracking
  • Yellows less than linseed oil over time
  • Also works as an effective brush cleaner that helps retain moisture in brush hairs
  • Dries faster than safflower and poppy oils but is equally favoured for using with whites and pale blue hues

Purified Poppy Oil

  • A clear oil medium to mix with and reduce light colours
  • Less inclined to yellow than Linseed Oil, but slower drying
  • Enhances gloss and flow, but too high a proportion prevents the colour from thorough drying
  • Should only be used for the final layers of a painting, and only in moderation (mixed with solvents)

Cold Pressed Linseed Oil

  • High quality, slightly yellow
  • Extracted without the use of heat
  • Increases gloss and transparency and reduces brush marks
  • Highly recommended for grinding pigments
  • Cold pressed Linseed oil is the least brittle form of linseed oil, very stable, dries thoroughly, least yellowing but more expensive than regular linseed oil

Lavender Spike Oil

  • Is used principally as a solvent, we include it here because artists who are new to this very ancient medium seem to classify it, in their own personal taxonomy, as a drying oil.
  • Spike Oil is a natural, low-toxic substitute for turpentine. It can be used as a solvent for oil painting and in egg-oil emulsion tempera recipes. It was used historically in oil painting as early as the fifteenth century. It is believed that spike oil improves the handling of oil-based paints, because it promotes oxidation instead of simply evaporating like most solvents. However, this has not been verified by scientific testing. A small amount goes a long way and it has a pleasant smell unlike other solvents. It evaporates slower than turpentine, mineral spirits (white spirits) and odorless mineral spirits 
  • One of the earliest of spike oil in painting was by the sixteenth century Italian Artist Gian Paolo Lomazzo. He recommended grinding colours in walnut oil and ‘other good things’.
  • Raffaelo Borghini provided a recipe for a ‘varnish that dries in the shade’ .The spirit varnish is made of powdered sandarac and spike oil that is boiled in a saucepan and applied luke warm before it congeals.
  • Spike oil can be used to thin paint like other common solvents such as turpentine. It is also an effective solvent for natural resins such as dammar, mastic, sandarac, gum elemi and copal in conjunction with turpentine.

ALKYD MEDIUMS

Alkyd is a synthetic resin that has come into popular use in colours and mediums within oil painting. The Winsor and Newton Griffin range of colours uses Alkyd resin as its binder. The advantages in doing so lie in the speed at which alkyd resin dries, and also its low cost. Unfortunately alkyd resin does not have the same colour holding capacities as a natural gum resin such as damar might have, which is used by Schmincke in their Mussini oil colour range. This means that the colour depth and brilliance is compromised and this is why we do not recommend alkys based paints at The PaintBox. However alkyd mediums are perfect for students or beginners, as well as for using when painting out of doors for all levels of ability (ease of use, practical reasons). It is also a good medium to use in the initial layers of a painting (underpainting) as it dries quickly, and one can then continue to work over the top with a medium that is made up of more lustrous, richer ingredients, if one so desires. Remember always the fat over lean rule – this means that the initial layers of oil colour should have less oil content than the layers applied over the top in order to allow the painting to dry solidly throughout the layers – this will give your painting stability and minimise the paint’s ability to absorb water from the air. Alkyd is also used in most oil based primers, and this allows these primers do dry a lot faster and be sold at a much lower price than the pure lead primer by Rublev. There are many alkyd mediums available, with varying consistencies and by a number of brands – check the details of each individual product for their unique characteristics. Brands Available Include: Gambilin Galkyd, Winsor and Newton Liquin (all varieties) and  Daler Rowney Alkyd Flow Medium

Traditional Oil Painting Mediums (Pre-Mixed)

There are a number of pre mixed mediums that use traditional, natural ingredients that achieve a greater degree of colour brilliance and depth. Because these mediums replicate the recipes used by painters for hundreds of years, we know the extent of their permanence and stability. If you know you are only going to use a specific ingredient for one purpose, i.e. as part of a particular medium, then buying a pre mixed medium might be the most cost and time effective way of doing so. If you are more likely to want to explore the possibilities with how to alter and manipulate mediums by altering the ingredients and their proportions, then it may be better to buy the ingredients separately to mix yourself.

Some of the Pre-mixed, traditional mediums available:

Langridge Glaze Medium

  • A mixture of Damar resin varnish, stand oil and turpentine
  • Achieves lustrous thin glazes
  • Ideal for fine detail and smooth brush work
  • Increases translucency and flow
  • Dries thoroughly throughout, ideal for initial and successive layers of paint

Langridge Low Toxic Painting Medium

  • A low odour solvent based medium mixed with linseed stand oil
  • Slow drying
  • Gloss
  • Ideal for fine detail work, glazing, smoothly blended areas with no brush marks
  • Faster drying can be facilitated with the addition of cobalt driers for thin layers of pain and the further addition of Calcium Driers for impasto layers

Michael Harding Damar Glaze Medium

  • Traditional glaze medium
  • Mix with tube oils or pigment to improve flow and translucency
  • Known for speeding the drying of oil colours.
  • For thin glazes, fine detail and smooth brushwork technique
  • Consists of Turps/Damar/Stand Oil/Cobalt Dryers

Michael Harding Resin Oil Wax Medium PM3

  • A crack resistant medium for soft impasto effects
  • Retains palette knife & brush strokes
  • To retain colour strength mix 1 part medium to 1 part oil colour
  • Made of Stand Oil/Damar Resin/Turpentine/Bleached Beeswax
  • Ideal for scumbling techniques

Michael Harding  Oil Paint Medium

  • A basic medium, designed to ease flow and increase gloss, transparency, depth and the beauty of pigment colour.
  • Pale non yellowing  linseed stand oil/double rectified turpentine.
  • Gives flowing quality when mixed with oils in ratio 10:1
  • After 8-10 hours drying, gives rich brilliant effect without excessive gloss

Rublev Oleogel

  • Facilitates the flow of oil paint, levels out brush strokes and can be used as a glaze
  • Can assist the traditional oil painter and the wet on wet artist
  • Made from a mix of fumed silica and Linseed Stand Oil
  • Accelerates Drying

OTHER INGREDIENTS FOR OIL PAINTING MEDIUMS

Below is a brief guide to other ingredients that you might mix with oil to make your own oil painting mediums based on traditional recipes.

Artists White Spirit

  • A volatile flammable dilutant for thinning oil colours and cleaning brushes, to be used with care
  • Slower drying than turps
  • Does not deteriorate on storage
  • Less viscous than turpentine
  • Evaporates faster (faster drying times) than turpentine
  • Is more abrasive than turpentine and will break the oil paint down in a less controllable way
  • Gives more watery mixes than turpentine
  • Does not have a gum residue like un-distilled decorator’s turpentine, which causes instability and yellowing when used as part of a painting medium
  • More refined than decorator’s white spirit, and as a result is more stable when drying and does not leave any tackiness or undesired residue
  • Not to be used with professional oil colour
  • Similar to Langridge Low Toxic Solvent

Distilled Turpentine (available by Winsor and Newton & Michael Harding)

  • Fast evaporating, highly refined distillate sourced from the gum of pine trees
  • Suitable for removing varnish (damar)
  • Keep tightly closed and away from light to prevent oxidation
  • Do not use if it has thickened
  • Mix with refined or cold pressed Linseed oil, or stand oil, to make a professional painter’s medium. Add siccative to speed drying, and a small quantity of retouching varnish to increase gloss or create a glaze medium
  • Winsor and Newton and Michael Harding distil their turpentine to minimise the presence of impurities that compromise stability in the paint layers
  • Warning: may suffer some discolouration if exposed to air over a prolonged period of time

Winsor & Newton Sansodor

  • A petroleum based mineral spirit solvent that has had harmful aromatic solvents found in its hydrocarbons removed
  • Evaporates slowly
  • Increases blending time
  • Suitable for thinning oil colours and cleaning brushes
  • Use in a well-ventilated area

Dammar Varnish (available by Michael Harding, and a spray by Winsor & Newton)

  • Traditional general varnish with a high gloss finish for protection of oil, alkyd and acrylic paintings
  • Stable, translucent and glossy when dry
  • Made of natural damar (dammar) resin and turpentine
  • Very pale yellow
  • Fast drying
  • Can be used as a final picture varnish (removable with turpentine) or in very small quantities within an oil painting medium

Oil of Spike Lavender (Rublev)

  • Similar properties to turps but slower rate of evaporation
  • Improves levelling quality of brush marks
  • Pleasant odour
  • Less toxic than White Spirit and Turpentine
  • Only small quantities are required

Retouching Varnish (Langridge & Winsor and Newton)

  • Damar resin/white spirit
  • Rectifies dull areas caused by sinking of paint. Also helps adhesion of succeeding layer
  • Can be used as a final varnish to protect work from dust as well as in a painting medium in very small quantities

Pumice Powder (available by Langridge.)

  • Add to acrylic mediums or gesso to create a textured ground, particularly good for gestural soft pastel work

Rectified Spirit of Turpentine (Michael Harding)

  • Volatile colourless liquid distilled from pine sap
  • Greater wetting powers than white spirit
  • Used to thin oil paint

Did you know?

The rectifying process is carried out by steaming out the spirits of the turpentine. This is different process to distillation of the spirits, yet serves the same purpose of removing any impurities that may have a disadvantageous effect on its drying process. Rectification is a mechanical process that uses water and is a much newer process of purification than distillation.

Beeswax (available by Gamblin, Sennelier, Langridge and Michael Harding Ready Mixed Paste Medium)

Beeswax is a popular medium among artists who like to paint more gesturally or with impasto colour. It is a mixture of linseed stand oil and bleached beeswax paste. It thickens oil colour and dries with a semi-matte sheen. Beeswax is particularly effective when mixed with semi-opaque and opaque colours.

SOLVENTS

What is the difference between White Spirit and Turpentine?

Solvents can be divided into two main categories: Those that are extracted from pine trees and those which are petroleum based. Generally it is considered that the solvents that are extracted from pine trees are better suited to using in painting mediums, and in the cleaning of brushes etc., but the quality of these gum-resin based solvents (turpentine) vary hugely, so it is worth considering this when making your decision on which to buy. The quality of these is reflected in the price you pay. Many manufacturers call their high quality turpentine different names, and so if one comes across an English distilled turpentine, or a rectified turpentine, or a gum spirits of turpentine, one is going to be looking at pretty much the same product, and it would all come down to testing each one out to see which one does the job best for you.

Pure turpentine contains more impurities than English Distilled turpentine but is great as a brush cleaner prior to rinsing with soap and lukewarm water. Turpentine is made from the gum resin of pine trees, which is then purified or distilled or rectified to remove the impurities found in the resin, leaving a pleasant, pine smelling, yet effective thinner and cleaner of oil paint. If your turpentine does not smell as good, it could be down to the fact that it may have not been purified to the same extent, or that it may have been made from the mulch and dead pine tree leaves and branches as opposed to a live tree source. Such turpentines will be less stable and although may be cost effective, we would only really recommend these for cleaning brushes and not as an ingredient within an oil paint medium. We strongly recommend using all qualities of varieties of turpentine in a well-ventilated work area, as inhalation of the fumes should be kept to a minimum.

Warning – turpentine may suffer some discolouration if exposed to air over a prolonged period of time, so always worth keeping the lid on tight when not in use.

White Spirit is a paraffin derived, clear transparent liquid, and generally speaking is considered too unstable to be used in oil paint mediums, although can be used as a very effective cleaner for brushes after an oil painting session. However there are special ‘Artist’s White Spirit’ such as the one available from Winsor and Newton, that Winsor and Newton claim is suitable for painting with as part of a medium.

Low odour solvent is another petroleum based thinner, which has had its harmful aromatic solvents removed from its hydrocarbons – while Langridge  calls theirs a ‘Low Toxic Solvent’, Winsor and Newton call theirs ‘Sansodor’ (a name derived from the French for ‘without odour’) and it is worth remembering that these are much the same product. The key things to remember with these are that they are less stable than the very finest turpentines, they dry slower when mixed as part of an oil painting medium, and even if they do not emit as strong an aroma into the atmosphere, they still contain harmful fumes that should not be inhaled and so a well-ventilated studio is of paramount importance to the healthy artist’s well-being!

If the artist is concerned about one’s well-being in the studio and would like to find a friendlier solvent to use, then Zest It is our recommendation. Zest It is a solvent, primarily for use by oil painters. It is made from an Aliphatic Hydrocarbon and pure food grade Citrus Oil. It has a neutral pH value and contains no CFC’s or Aromatics and has low VOC’s. It is a clear, colourless liquid which has a pleasant ‘citrus’ smell, is inherently biodegradable and evaporates without leaving any residue. Independent laboratory tests show it has no detrimental effect to the oil paint or pigment quality, proven stability and a long active life. It does not emit any harmful paint fumes and although it is a little more expensive than other solvents, it can be recycled (left to stand so residue sinks to the bottom, and the clear Zest it can be decanted into another vessel to be used again). If you are looking for a solvent with a longer history of use, then Oil of Spike Lavender smells of fresh spring meadows, and has been used by oil painters for hundreds of years. It does emit some fumes but not as many as turpentine, low odour solvent or white spirit might, and it is less potent, and less abrasive than any of those solvents. It has a thicker consistency, and is known to be great for maintaining the quality of brush hairs when used straight as a brush cleaner at the end of a painting session, as well as part of a lustrous, easy-to-use painting medium when mixed with stand oil. It is pricey but a real treat for any serious oil painter.

Larch Venice Turpentine is not for cleaning brushes – it is a thick, thixotropic natural balsam that is extracted from resin (oleoresin) and mixes beautifully with oils (especially walnut or stand oil) and a little distilled turpentine to make a thick, lustrous, glossy, rich oil painting medium that increases the transparency of your colours.

Pure Turpentine

Pure Turpentine is a natural product distilled from pine trees. It can be used in oil painting mediums by mixing with oil (linseed, linseed stand, walnut or safflower etc.). It is also great for cleaning brushes as it is effective yet is not as strong as white spirit and will not dry out the natural moisture of your brush hairs as much. However please note that prolonged exposure of natural hairs to any solvent will accelerate the deterioration of the quality of the hair and cause them to become brittle and break more easily. Turpentine can also be used to thin oil based varnishes, and is superior to white spirit in its ability to blend easily with oils to create even mixtures. To make your own varnish you can simply suspend damar resin crystals wrapped in a lint free cloth into a jar of pure turpentine until the crystals have dissolved. Turpentine’s slow evaporation rate creates a gradual drying time, which again, allows for a more lustrous finish to dried colour that has been mixed with turps.

Warning – turpentine may suffer some discolouration if exposed to air over a prolonged period of time, so always worth keeping the lid on tight when not in use.

Larch Venice Turpentine

Larch Venice Turpentine is a slow drying thixotropic balsam for use in mediums and varnishes. Pure resin from the Austrian Larch tree purified and slightly heated when decanted. Dilute with turpentine or place in warm water bath to obtain fluid consistency.

Varnish – A General Overview

A layer of varnish on a finished painting will protect it from dust, dirt, grease and UV rays. It will also even out any unevenness of sheen on a paint surface e.g. a gloss varnish will make the whole picture surface equally glossy. All solvent varnishes are made up of resin and solvent. The resin provides the stable, solid, fast drying and glossy component of the varnish, and the solvent the liquid vehicle, which evaporates in the air with time which allows the resin to solidify once more after the varnish application. There are 2 main types of solvent varnish – a final picture varnish, and retouching varnish. The difference between the two is that the picture varnish will have a greater resin to turpentine ratio than the retouching varnish. The reason why is that the picture varnish is designed to be more concentrated to form a more solid, continuous layer of resin over a finished work, the layer will be even in its appearance. Its strong, solid structure will not allow water or other liquids to permeate through it, and conversely will not allow any liquid still contained within any semi-dry oil colour beneath the layer of varnish to escape into the atmosphere.

If a painting is not sufficiently dry when varnished with a final picture varnish blooming may appear, as well as more visible cracks in the varnish as the paint beneath shifts. This is why it is very important to not apply a final picture varnish until the painting is at least 6 months old. Picture varnishes should be removable so that they can be taken off and replaced with a new layer if the old layer gets damaged or dirty, and all good varnishes will state the best means of removing varnish (although it will be with the use of the solvent that is used in the varnish itself). Because retouching varnish has more solvent in it, when it dries liquids are able to permeate through the layer of varnish, which means that the painting does not need to be fully dry before its application. It is used as a temporary protection layer as well as a device to unify sheen during the painting process.

Small quantities of varnish are also sometimes used in oil painting mediums to act as a siccative (to speed drying) as well as add a little more gloss to the finish. The resins used vary but typically it is damar resin if it is not a synthetic alternative, such as ketone. Damar resin is extracted from the Dipterocarpaceae family of trees in India and East Asia, and as well as in varnishes, can also be found in the binding of Schmincke Mussini oil colours. It is thought to increase the appearance of colour brilliance, and is a good ingredient in oil painting mediums as it has a good colour holding capacity.

Generally speaking, damar is preferred to synthetic resin as it is thought to provide a deeper, more lustrous finish, as well as being less likely to yellow with time and having more stability. The solvents are either turpentine or white spirit, which dries slightly slower than turpentine. Winsor and Newton also offer a range of Artisan varnishes which are water-based and to be used to protect fully dried paintings created with the use of Artisan colours, and can only be removed with the special Artisan varnish remover. All solvent varnishes can be applied with a spray or a thin flat varnish brush, and can be used on all dry oil, alkyd or acrylic works.

Matt Varnish

Matt varnishes can be made 2 ways – either with the use of a wax that is matt anyway when dry, or by adding a matting agent to a varnish that would otherwise dry gloss. Michael Harding’s matt varnish is made with beeswax and double rectified turpentine and Langridge  also produce a similar beeswax paste picture varnish. Langridge’s ‘Matt Varnish’ contains artists White Spirit., Matting Silica and  paraloid B67 resin which is elastic and adhesive in its nature, as well as matt in appearance. Matt varnishes by Royal Talens and Langridge  both contain a silica matting agent which serves its purpose but the only snag is that the matting agent tends to be marginally denser than the other ingredients in the varnish and will sink to the bottom of the bottle over time. This may lead to an uneven sheen, so it is absolutely vital to give your bottle of matt varnish a thorough stir or shake prior to use.

How to apply varnish – brush and spray

Applying Sennelier Varnish Using a Spray Can

  1. Try not to store aerosols below 15’C I as f they have been stored around this temperature do not use them until they come up to ambient again. All aerosols contain a mix of product and propellant and at lower temperatures the products wants to “drop out of solution” and so could either block the nozzle, or worse, come out of the nozzle as “blobs of product” which then fall on the work itself.
  2. Always shake the container vigorously before use to ensure the contents are homogenous.
  3. Always hold the container upside and spray for a couple of seconds – this will send a spray of propellant only out of the nozzle and clear it
  4. Always do this at the end of use as well to clear the nozzle of material build up.
  5. Be careful if using the container extensively over a short period of time as the contents temperature will drop with a potential for the product to “”drop out of solution”” – this applies to all aerosols but is only likely to be noticed during extensive use.
  6. Always spray with the can almost vertical and allow the contents to “”cascade onto the work”
  7. When spraying the can is to be held at least 25-30cm (10-12 inches) away from the work
  8. Mount the work onto “”waste material”” and spray side to side beyond the extremities of the work to ensure full coverage
  9. For porous, unprimed surfaces such as card, canvas, hardboard, plaster etc. apply a thin layer of gloss varnish before applying any matt or satin varnish.

Applying Varnish Using a Brush

  1. Use a 1”- 4” flat wide, soft, tightly packed, varnishing brush (such as the Winsor & Newton Monarch glazing/varnishing brush).  Keep it clean and use it only for varnishing.
  2. Place the work to be varnished flat on a table – do not varnish vertically.
  3. Apply the varnish in 1-3 thin coats, rather than 1 thick coat. A thick coat will take longer to dry, may dry cloudy, drip or sag during application and has a greater chance of showing brush strokes when dry.
  4. Thinned varnish is more susceptible to producing bubbles. Do not be vigorous in your application.
  5. Apply in long even strokes to cover the surface top to bottom while moving from one side to the other. While working, inspect the varnish layer at all angles for bubbles. Even them out immediately.
  6. Once you leave an area, do not go back over areas that you have done. If you do, you risk dragging partially dry resin into wet, which will dry cloudy over dark colours. If any areas were missed, allow to dry completely and re-varnish.
  7. After varnishing, it is recommended that the surface should be shielded from dust with a protective plastic film “tent”

How to make your own Dammar Varnish from Dammar Crystals

It is both cheap and easy to make dammar varnish, to use either as a retouching varnish or a final picture varnish. It is a case of diluting one part dammar crystals to one part turpentine. Wrap your crystals in a piece of cheesecloth or muslin and tie at one end, and suspend in a jar of your solvent. As stated earlier, the more refined the solvent the easier to use the varnish, so try and use something that has been rectified or distilled of its impurities. You will need to gently stir every now and then for the following 2-3 days, as the crystals break down. After about 3 days all the crystals should have dissolved and you then have your damar concentrate. With this you can either a) make picture varnish, by mixing 1 part damar concentrate to one part solvent, or b) make retouching varnish by mixing one part damar concentrate to 3 parts turpentine. You may also make a matt varnish by also diluting a quantity of beeswax in the same jar of damar concentrate. 

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