Tips & Techniques

Solvents Tips & Techniques

Thinners are used to dilute the colour and clean brushes and palettes after painting. The same solvents can be used with all types of oil colour, with one exception. Water mixable oils are intended for use with water to avoid the need for traditional solvents.

Turpentine is the traditional solvent, with a characteristic smell. It maintains the oiliness of the colour in use. White spirit (mineral spirits) and Sansodor are petroleum distillates. The first petroleum distillates were thought only to be good enough to clean brushes. This is no longer true of solvents supplied as artists’ quality.

White spirit makes a watery mixture with the colour and evaporates more quickly. Sansodor performs like turpentine but has a low odour and is the least hazardous of the solvents. All solvents should be used in a well ventilated room.

Using Artists' Solvents

Make sure you use artists’ quality solvents. Solvents sold in hardware stores are not expected to be used in fine art and yellowing or non - drying can result.

Avoiding Overthinning

Solvents thin the oil colour by diluting the linseed oil. If too much is used, there will be insufficient oil remaining to bind the pigment.  A matt or uneven finish will appear on the painting and the work will be susceptible to scuffing and damage. Overthinning is avoided by the use of mediums in addition to solvents.

White spirit makes a watery mixture with the colour and evaporates more quickly. Sansodor performs like turpentine but has a low odour and is the least hazardous of the solvents.  All solvents should be used in a well ventilated room.

Artists' Picture Cleaner

Artists' Picture Cleaner is a non-acid emulsion of natural resins and essential oils designed for the cleaning of varnished oil paintings. It is perfectly safe and harmless if used according to the directions and is an excellent product for its limited purpose.

A picture which needs to have the old varnish removed should be entrusted to a competent picture restorer. Artists' Picture Cleaner will remove surface dirt and the products of oxidation in the old varnish. It effects a wonderful improvement in most cases, but it must be clearly understood that it acts only as a cleaner. Any attempt to remove the old varnish by copious application of the cleaner and by hard rubbing will damage the painting and we cannot accept any responsibility for this outcome.

Unvarnished oil pantings may also be treated with the cleaner but great care is necessary and the process should be stopped immediately if the colour of the painting is removed. Heavily varnished tempera paintings may also be cleaned but you should never use it to clean an unvarnished tempera painting. Artists' Picture Cleaner is also unsuitable for water colour paintings.

Artists' Picture Cleaner is a highly recommended product. Users have said that it does amazingly well if you have an oil painting which is dirty but otherwise in good condition. It allows you to improve paintings simply and inexpensively, however, if you are in any doubt about the condition of the painting or if the varnish is cracked, let the necessary work be done by an expert.

Directions for Use

  1. Remove the oil painting from its frame and lay it flat on a table.
  2. Shake the bottle of Artists' Picture Cleaner vigorously to mix the contents thoroughly. The emulstion must be uniformly white and creamy before it can be used. Shake the bottle every time you want to apply cleaner to your pad of cotton wool.
  3. Moisten a wad of cotton wool with the cleaning emulsion.
  4. Apply to the surface of the painting by means of a gentle, circular motion. Never allow liquid to remain on one part of the surface. Keep the cleaner evenly distributed over the whole area.
  5. Take a fresh wad of cotton-wool as soon as the old piece becomes dirty. Repeat the process as long as necessary to achieve the desired result. Remember that some time will be required for the essential oils to penetrate the hardened varnish, and that the exercise of patience will be well rewarded. Never rub hard and be sparing with the amount of cleaner used.
  6. Stop the cleaning immediately if colour is observed on the cotton wool.
  7. When no more dirt is brought off on the cotton wool, the painting should be wiped over with fresh cotton wool moistend with Distilled Turpentine. Do this a second time with fresh cotton wool and turpentine.
  8. The surface will now be slightly tacky. Put the picture aside in a warm dust-free atmosphere until the surface has re-hardened. This may take a few hours.
  9. If considered desirable the picture can be re-varnished with the Winsor & Newton range of varnishes depending on the effect required.

Oil Medium Tips & Techniques

Painting with oil colour almost always involves the use of Mediums and Oils in order to further control the colour, prevent overthinning (see also solvents) and maintain the flexibility of the paint film (fat over lean). 

At Winsor & Newton we can separate our mediums into four categories:

  • Linseed Oils
  • Oil Mediums
  • Fast Drying Mediums and
  • Water Mixable Mediums

Below you will find an explanation of how mediums are used and an insight into the effects that you can create with them. 

Working with oil colour is a skill that needs to be learnt and in this section we will also explain a few of the oil colour rules such as oiling out, how to combine different mediums, fat over lean and why varnishes should never be used as mediums.

Linseed Oils

Linseed oil is the traditional medium, as it is the binder for most oil colours. Generally oils dilute the colour, increasing gloss and transparency and are used in combination with solvents. The consistency, colour and drying time of linseed oil can be varied by different processing.  Read more about Linseed oil here.

Oil Mediums

Oil mediums are ready made mixtures of particularly suitable linseed oils with solvents. They can be used as general purpuse mediums and can be used directly for oiling out.

Fast Drying Mediums

Modern resins called alkyds are used to make fast drying mediums for oil painting. These are extremely popular because they generally halve the drying times of the colours.

Water Mixable Mediums

Water mixable mediums are available for use with Artisan Water Mixable Oil Colours. These dedicated mediums ensure that all the traditional oil colour techniques can be achieved without the use of turpentine or white spirit (mineral spirits). In addition, all Artisan bottles are easy to open as they do not require child resistant caps.

Combining Different Mediums

All the conventional mediums can be mixed. However, the structure of the painting is under less stress in the long term if mixtures are avoided.

We recommend Water Mixable Mediums to be used exclusively with Artisan colours in order to benefit from the use of water instead of solvents.

Not Using Varnishes as Mediums

Picture varnishes are not recommended as constituent parts of mediums because of their resoluble nature. Neither should they be used as intermediate layers in oil paintings.

Oil Painting Rules

When painting with oil colour, artists must adhere to three conventional oil painting rules:

  1. Fat over lean - (see explanation below). When oil painting in layers, each successive layer must be more flexible than the one underneath. This rule is maintained by adding more medium to each successive layer.
  2. Thick over thin - Thick layers of oil colour are best applied over thin under layers. Thin layers on impasto paintings are likely to crack.
  3. Slow over fast drying colour - Slow drying colours should not form continuous under layers as any faster drying layers on top may crack.

Oil Painting Techniques and Effects

Artists can create a multitude of painting effects with the use of mediums. Below are a few illustrations which explain how they work and hopefully inspire you to try them out.

Glazing is the build up of layers of transparent or semi trasnparent colour over dry underlayers. It is a lengthy technique where the effects in oil are unmatched when compared to other media. Liquin original is an excellent glazing medium and will reduce brushmarks.
Loosely brush a thin film of opaque or semi-opaque colour over your underpainting. This may actually show through in places and can retain an important influence on the surface appearance of the painting. Liquin can be used to thin the colour or if you prefer a thick texture, use Liquin Impasto or Liquin Oleopasto.
Stipple Effect
A bristle brush and thick viscous colour can create a "stipple" texture. Tube colour alone will work well or colour mixed with Liquin Oleopasto.

"S'graffito", the technique of scratching into a wet oil film, can be done with the pointed end of a brush, painting knife or any scraping device.

It is effective in defining outlines or details for expressive effects. If you want more time for scraping back the colour you can slow the drying by using Refined Linseed Oil or Artists' Painting Medium with the colours.

This is the technique of applying paint thickly, so that the brush strokes are plainly visible and create a textured effect. 

Liquin Oleopasto will add texture and increase the transparency. For thick impasto, build the texture in several layers allowing each to dry first. 

Many artists complete the underpainting ofa project in faster drying colour (such as Griffin Fast Drying Colour) to save time and then go on to complete it with conventional colour.

Underpainting can be done in monochrome using any colour, or it can be done in full colour if using fast drying colours.

Oiling Out

Oiling out is the application of an oil medium to a painting which has sunk (become dull), or lost its oil to the layer underneath. The most common causes for this are an over- absorbent, cheap ground or the use of too much solvent and insufficient or no medium. When the colour is dry, Artists’ Painting Medium should be sparingly rubbed into any sunken areas with a clean cloth.

Wipe off any residue and leave to dry for a day or two. If smaller, dull areas remain, repeat the process until the painting has regained an even sheen. Varnishes should not be used for the purpose of recovering the lustre of a dead painting. For a faster drying oiling out medium, use Thickened Linseed Oil diluted with 50% white spirit (mineral spirits).

Fat over Lean

Fat over lean is better understood if considered as ‘flexible over less flexible’. When painting in layers, the proportion of medium used in each layer should be increased. The higher proportion of medium makes subsequent layers more flexible and prevents the painting from cracking. This rule has traditionally been kept by adding more and more oil to the solvent used. However, as Liquin is now more commonly used, it is the Liquin content which is increased. There is no need to use oil as well.

Varnish Tips & Techniques

Varnishes are used to protect the finished painting. Picture varnishes should be removable so that paintings can be cleaned when they have become dirty.

There are two important things to remember about varnishes:

  • Don't varnish too early, even the thinnest oil painting should be allowed to dry for 6 months. A minimum of one month is required for thin Griffin alkyd paintings.
  • Don't use varnishes as mediums, this would make the painting sensitive to solvent. An attempt to clean it in the future may remove the painting instead!

Application of varnish

Why Varnish?

The answer to that is different depending upon the media in which you’ve painted.  If the question is in regards to an oil painting, the answer is fairly simple: if you’ve followed all the rules of oil painting – fat over lean, slow drying over fast, thick layers over thin, all on a rigid, well-primed support – you’ll have a secure, durable paint film. 

Varnish is desirable for two key reasons: one, to bring the surface to a uniform gloss level (matt or gloss or somewhere in between), and; two, for protection from dust and other atmospheric contaminants.   “Dust can cause the most damage,” explains Alun Foster, Chief Chemist for Winsor Newton. “It is very abrasive and can be difficult to remove if it becomes embedded.” 

For an acrylic painting, the need is even more immediate and clear.  Why?  Because, as the acrylic film approaches it final dry state, the last few evaporating water molecules don’t fully “close the door” on their way out, leaving micro-pores in the film.  It’s these pores that cause the film to feel tacky, even when fully dry.  Even more important, they remain open indefinitely, meaning that the porous acrylic film can freely accumulate dust, grime, and smoke from the atmosphere.  While that grime may not seem to be much over a week or a month, it adds up over the course of years.  The best way to protect the painted acrylic film?  Varnish.

We’re often asked about varnishes for water colour. When dry, water colour doesn’t form a discrete, intact film like oils or acrylics.  In fact, water colour remains soluble when dry, and any applied varnish will “mingle’ with the colour layer, creating a film that is chemically and mechanically part of the painting surface.  If, at some later date, the varnish yellows or is damaged and requires removal, the painting will come with it. Obviously, if you’re interested in long-term stability, varnish over water colour is a bad idea.

Types of Varnishes

The ideal varnish offers three qualities: one, superb clarity, two, remove-ability (or ‘reverse-ability,’ in conservation parlance), and, three; easy and even application.

Varnishes are labelled ‘gloss’ and ‘matt’. However, there is a variety available made from different resins which provide relative levels of gloss, as many artists have their own personal preferences. Here are the most common choices:

As a conservation grade varnish, Winsor & Newton ConservArt Gloss offers high clarity and the low-molecular weight acrylic/ketone resin ensures long-term remove-ability.  In addition, UV stabilizers ensure film durability.   

Artists’ Original Matt Varnish is a removeable ketone resin/beeswax varnish that dries to a matt finish. 

Artists’ Gloss Varnish and Artists’ Matt Varnish are removeable, non-yellowing and can be blended to achieve an intermediate gloss level.

For acrylics, the vast majority of acrylic emulsion (water-based) varnishes on today’s market are – just like the acrylic emulsion colour – fully waterproof and non-removeable when dry. Winsor & Newton is the only manufacturer that makes three acrylic emulsion varnishes (Galeria Gloss Varnish, Galeria Satin Varnish and Galeria Matt Varnish) that are complemented with the Galeria Varnish Remover.  When used properly, this alkali-based formula is specifically formulated to reverse Winsor & Newton acrylic emulsion varnishes without damage to the acrylic paint film beneath.

Artists’ Gloss Varnish & Artists’ Original Matt and Conserv-Art Gloss & Artists’ Matt Varnish can be mixed to provide varying degrees of satin.

When to Varnish

When varnishing an oil painting, it’s essential to wait until the colour layer is fully dry and oxidized.  That can require from six months to a year (or longer), depending upon the thickness of the film.  How can you tell if the painting is ready to varnish? 

Acrylic paintings will dry and be ready for varnishing once water has fully evacuated from the film.  Depending upon film thickness, that will require anywhere between two days and a number of weeks.

How to apply Varnish

Here are eight simple steps to varnishing success:

  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 colors. If any areas were missed, allow to dry completely and re-varnish.
  7. After varnishing, we recommend that the surface should be shielded from dust with a protective plastic film “tent”.
  8.  For a matte surface, apply the first layer(s) using gloss varnish.  Because multiple layers of matte varnish will cloud, only the final layer should consist of the Matte varnish.