|On This Page:|
|- True Pigment Characteristics
- Contribution to a Balanced Spectrum
THE FUNCTION OF PIGMENTS
- Blacks and Greys
- Reds and Oranges
- Other Pigments
- The Effect of Artists’ Techniques on Permanence
- Functions of Binders
|- We Know Colour
- Winsor & Newton Oil Products
- Technical Information - Colour
- Solvents, Oils, Mediums & Varnishes
- Applications, Techniques & Tips
Every pigment is unique. Some are naturally opaque while others are transparent. Others offer very different qualities when applied in a thin film than when applied straight from the tube. Some offer dramatic tinting strength while others mix with great subtlety. We evaluate all pigments based upon the following qualities: mass tone (the colour straight from the tube), undertone (the bias of a colour when applied in a thin film), colour strength, and relative opacity. From the cadmiums, (which offer rich colour, great opacity and covering power) to the phthalocyanines (which are characterized by high key colour, jewel-like natural transparency and tremendous tinting strength),Winsor & Newton uses only pigments that best represent the finest characteristics of a specific colour.
The 20th century saw remarkable developments in the quality of pigments. While this has been accomplished largely as a result of innovations in other industries (automotive, ceramics and plastics, for example), the exponential increase in available hues and the dramatic increase in permanence have proven to be of tremendous benefit to fine artists. Winsor & Newton is now able to offer a balanced spectrum of traditional and modern colours that are notable for a level of permanence never before imagined by artists just a few decades ago. Ninety-eight percent of Winsor & Newton Artists’ Oil Colour is now rated as “Permanent for Artists’ Use.” This assumes the thinnest of washes or the palest of tints, as well as full strength colour.
The best possible spectrum in any range is one that allows the artist to mix the widest possible array of colours. Winsor & Newton selects pigments based, not just upon individual characteristics, but upon how those characteristics contribute to the overall mixing and expressive opportunities within the entire spectrum. All Winsor & Newton ranges can be used to explore the full range of colour mixing qualities, from warm to cool, from high to low chroma, and everything else in between.
Pigments, in addition to having unique optical properties, have different physical characteristics. Some are jagged and irregular; others are smooth and round. Some absorb a great deal of oil during milling; others absorb but a small amount. In short, every pigment requires different procedures, skills, and details during the milling process.
Here’s a working definition for pigment: Pigments are compounds that remain as discrete particles, and can be ground into suspension, within a vehicle. By contrast, a dye is a compound that goes into solution within its solvent, and that bleeds into surrounding materials. There’s a common misconception that all pigments are lightfast and dyes are not. Not so. Lightfastness has little or nothing to do with whether or not a compound works as a dye or as a pigment.
Organic vs. inorganic. These are terms used in describing chemicals comprised of specific elements. And the designation works when describing pigments, as well. Inorganic compounds are made from elements like metals (cadmium, cobalt, and iron, for example) while organic compounds are made from molecules that contain carbon in combination with hydrogen, and often with oxygen or nitrogen. Organic compounds are made from the same basic building blocks that make life. But definitions aren’t always hard and fast, and metal compounds are often constituents in organic pigments. Copper, for example, is present in copper phthalocyanine.
Inorganic earth pigments (like yellow ochre and raw umber) have been used since pre- historic times. Inorganic pigments became common in the nineteenth century when the industrial revolution and developments in chemistry made it possible to combine metals like cadmium, or cobalt with other compounds. The results were products, like cadmium sulfide (which could be “adjusted” by adding varying degrees of selenium to make oranges and reds), that were highly stable, far less prone to fading, and that could be ground into a suspension within a vehicle like linseed oil for oil paint.
The first organic pigments were found in nature. Plant compounds, like woad, were used to produce indigo dye for cloth. It didn’t take long to work out that indigo could also be made into a pigment. Indian yellow was an organic pigment made from the urine of cattle that had been fed Mango leaves at Monghyr in Bengal. The pigment was also known by the colourful name, “Indian Puree.” Both of these organic colours were derived from environmental sources, and are different from modern, laboratory-synthesized pigment.
The very first, fully synthesized pigment was the result of an accident. Around 1704, a colourman named Diesbach was preparing a Florentine lake colour. By mistake, he used potash that had been inadvertently contaminated with an animal oil. Instead of the red lake that was his aim, he got a much paler hue. While trying to adjust the colour further, he got a purple and then a deep blue. Prussian blue, in fact; the first laboratory synthesized pigment.
There’s no question that there have been more advances in pigment and colour chemistry in the last fifty years than during the previous two millennia. The current revolution in organic pigments began early in the twentieth century, when the Germans synthesized arylamide yellow. Arylamides have continued to evolve in permanence and variety of hue, and are still used today. Winsor & Newton use the pigment in the production of Winsor yellows and cadmium hues.
In addition to setting a standard for modern laboratory synthesis, arylamide became the standard bearer for pigment nomenclature, as well, with the names of organic pigments becoming increasingly polysyllabic. Anthraquinones, dioxazines, pyrroles, phthalocyanines, and benzimidazalones are all products of 20th century pigment chemistry.
Working with organic and inorganic colours. Not only are there generalities that apply to the production of organic pigments (synthesized from carbon-based compounds in the laboratory), and inorganic colours (usually made from metallic elements), there are generalities that apply to how they function upon the palette, as well. Before outlining some of these characteristics, it’s worth reminding the reader that these are not “rules.” As said at the beginning of this section, every pigment is unique. And, sometimes, there are “organic-like” qualities that show up in inorganic colours and vice-versa. That said, here are three general principles:
When mixed, inorganic colours tend to more closely replicate the tonalities of the natural world. Because of the nature of reflected light and shadow, we live in a world of pure colours that combine into rich shades of grey. The physical and optical properties of inorganic colours, quite often, more closely capture those qualities of natural light and shadowed colour.
Organic colours are brighter, and tend to make brighter mixes. Because of their purity, natural translucency, and tinting strength, organic pigments produce mixed secondary and tertiary colour that tend to remain closer to the high chroma of their “parent” primaries.
The two can intermix quite happily. Try adding a small amount of an organic colour to an inorganic mix that has gone too grey or dull. You’ll find that you can often bring surprising “punch” to mixes that are made largely from inorganic pigments, without losing their natural character.
Below are comments and descriptions about pigments that are commonly used in milling fine colour:
The first whites, used as colourant since pre-historic times, were from chalks taken from the earth. Illustrating that tonal opposites can come from identical sources, it’s interesting to note that, very early in the history of colour, bones were used for making white as well as black pigments. Calcining (incinerating) the bones of animals produced a grey-white ash that was still in use through the middle ages on paper or parchment to create a gritty surface. If those same bones are charred within a sealed environment, the resulting product is black; bone black, in fact.
The whites available today offer a wide array of characteristics, in differing degrees of opacity, and are well suited for mixing or covering, depending upon the unique needs of the artist.
Chinese White. Invented by Winsor & Newton in 1834. The first semi-opaque permanent white. Made from Zinc White.
Cremnitz White. Pure lead white, ground in safflower oil, as prefered by some artists’ using traditional techniques.
Flake White. Basic lead carbonate, with a small addition of zinc, which improves its colour and consistency. Flake White No. 1 is formulated to a thicker consistency than Flake White No. 2.
Foundation White. Flake White ground in linseed oil for extensive underpainting or modelling.
Iridescent White. A mica-based pigment available in Artists’ Oil Colour for pearlescent white effects. It is lightfast, and can be intermixed.
Soft Mixing White. Available in Winton. Made from Titanium pigment. A soft consistency, excellent for strong tints and avoiding chalkiness.
Titanium White. The most opaque, highest tinting white. First made in 1870, introduced as an artists’ colour in the 1920’s. Now the most popular white.
Zinc White. The most transparent white with the lowest tinting strength. First made in the 18th century, entered common usage by the 1840’s.
The very first pre-historic black pigments are still in popular use today. Bone black (described, on page 45, as related to bone white) is offered under the name “Ivory Black.” And Lamp Black is common in all media. Both are, technically, the very first organic colours, having been produced from animal sources. Both are highly stable forms of dense, elemental carbon. And there’s nothing more permanent than elemental carbon, whether in the form of these simple pigments, or as layered graphite, or pressed into that most-valued of all crystal-lattice structures: the diamond. Even after all the breathtaking expertise and sophistication that has characterized pigment chemistry over the last century, there’s still nothing that surpasses the versatility, the workability, and the permanence of these first carbon pigments first recognized by men and women sitting around the fire some 40,000 years ago.
Blue Black. In oil colour, this is a mixture of Ivory Black and Ultramarine.
Charcoal Grey. In oil colour, this is ground charcoal.
Davy’s Gray. Originally a special variety of slate, now strengthened by the addition of other colours. Excellent for toning down mixtures without blackening them.
Ivory Black. Calcined bones, not using ivory.
Lamp Black. The oldest pigment made by man, made by collecting soot from burning oils.
Payne’s Gray. A blue grey made from a mixture of crimson, blue and black. William Payne, a water colourist from Devon (active 1776-1830) is thought to be the source of the colour’s name.
Sepia. Originally the ink from the bags of the cuttle fish. Now made from a mixture of umber and black.
Along with the prehistoric carbon blacks and whites, the earth colours made up the majority of the artists’ palette until the Middle Ages. The jewel-like transparency (due to the presence of aluminium silicate within the pigment) and the rich tonality that comes with the very highest quality sienna earths were defining colours for artists from Rembrandt to Wyeth. Sadly, at the turn of the 21st century, the finest Sienna earths are becoming increasingly difficult to obtain, forcing manufacturers that insist upon using the natural pigment to produce a lesser quality colour. Winsor & Newton has, in many cases, chosen to make use of recently developed synthetic earth pigments rather than the remaining natural earths. Even though laboratory-derived, the new synthetic iron oxides are of a physical structure that offers many of qualities that made the original earth colours so extraordinary.
Over the centuries, pigments have come from a variety of “colourful” sources, and one of the most interesting (and undeniably gruesome) was “Mummy Brown.” First documented in the 16th century, mummies from Egypt were, in fact, ground into pigment. The characteristic colour was the result of asphaltum, a bituminous solid or semi-solid earth found in regions of oil deposits, and used in the embalming of Egyptian mummies. Its use ceased in the 19th Century.
Burnt Sienna. Originally calcined Raw Sienna. Winsor & Newton generally use a synthetic iron oxide to match the brilliance and transparency of their original.
Burnt Umber. Calcined Raw Umber.
Gold Ochre. Originally a variety of natural earth. Superseded by synthetic iron oxide.
Indian Red. Originally a variety of natural earth. Superseded by synthetic iron oxide.
Light Red. Originally calcined yellow ochre. Superseded by synthetic iron oxides.
Mars colours. Red, brown and yellow earths made from synthetic iron oxides. Usually opaque.
Raw Sienna. Natural yellow earth. From Winsor & Newton, the colour is bright, transparent, and has a low tinting strength. In some cases, synthetic iron oxide is substituted.
Raw Umber. Natural iron oxide.
Terra Rosa. Originally a variety of natural earth. Superseded by synthetic iron oxide.
Vandyke Brown. Originally bituminous earth, generally replaced by umber. Winsor & Newton tests do not show this pigment fading in oil colour.
Venetian Red. Originally a variety of natural earth. Superseded by synthetic iron oxides.
Yellow Ochre. Natural iron oxide.
The most dynamic, fiery red - until the introduction of Cadmium red in the early 20th century - was Vermilion. Originally produced as crushed pigment from the mineral “cinnabar,” the colour is a form of mercuric sulphide (HgS). Cinnabar was used by the Greeks and Romans, and transformed into the purer form of Vermilion, most likely, by the Chinese. The resulting rich, remarkably clear hue was unmatched by any other pigment. Because of toxic hazards present during the manufacturing process, Vermilion is no longer available. Luckily, by the time the colour was being phased out of production, the cadmiums had become available as replacement.
Over the last few decades, there has been explosive growth in the availability of reds and oranges made from organic, synthetic sources. Will one of those eventually supplant cadmium, as cadmium did Vermilion? Although perylene, pyrrole, quinacridone, and naphthol reds have their own, unique and quite wonderful qualities, there is still no red pigment that matches cadmium in the purity and “temperature” of hue, opacity, and that matches its mixing characteristics.
Alizarin Crimson. Introduced in 1868 and was a mainstay of the artists’ palette until the 1980’s. Superceded by Permanent Alizarin Crimson.
Benzimidazalone colours. Orange and maroon varieties first introduced in the 1980’s. Good lightfastness, used under various names in different ranges.
Bright Red. Arylamide reds of good lightfastness, first used by Winsor & Newton in the late 1970’s.
Brown Madder. Originally an alizarin lake, now made from quinacridone or benzimidazalone for greater lightfastness.
Cadmiums. Includes shades of yellows and oranges as well as reds with unrivalled opacity. Winsor & Newton do not use the lower quality cadmium-bariums. Yellows introduced in 1846, reds after 1910.
Carmine. A lake prepared from the female cochineal beetle. Fugitive. Only available in Artists’ Oil Colour and in pigment form. First used in the 16th century.
Magenta. Made from a mixture of violet pigments. Winsor & Newton oil colour magentas are permanent.
Naphthol reds. A large group of red organic pigments, first introduced circa 1920. Winsor & Newton choose the most lightfast naphthol pigments available for use in their ranges.
Perinone Orange. A ightfast orange. Dye form discovered in 1920’s.
Quinacridones. Violets and browns as well as reds. Highly transparent and lightfast. First introduced by Winsor & Newton in 1958 as Permanent Rose and Permanent Magenta.
Rose Dore. A beautiful, translucent pink. Made from rose madder in oil colour.
Rose Madder Genuine/Deep. Lake pigments made exclusively by Winsor & Newton from an original recipe developed in 1806 by master colourman George Field. Exquisite transparent pinks.
Scarlet Lake. Originally a lake pigment, Scarlet Lake is now made with a yellow shade naphthol red.
Vermilion. The bright, passionate red of Vermeer. Made from mercuric sulphide, and no longer available for health and safety reasons. Substitutes are offered based upon cadmium and a variety of other mixtures.
The earliest yellows were the earth colours, many of which are still in use today. Indian yellow is among the most storied of pigments (see below), in part because of its origin, but also out of sheer wonder that anyone would even think to make intentional use of the raw material.
Arylamide yellows. A group of synthetic organic yellows of good permanence. One of the earliest groups of laboratory derived organic pigments. First made circa 1909. The more recent arylamides have greater permanence and are used for Winsor Yellows and Cadmium hues.
Aureolin. Cobalt yellow. Originally introduced by William Winsor, circa 1862.
Azo condensation yellows. Introduced in the 1980’s. Used in Transparent Yellow.
Chromes. Reds and oranges as well as yellows of good opacity and low cost. No longer used for health and safety reasons.
Indian Yellow. Originally made exclusively from the urine of cows that had been fed exclusively on mango leaves in Monghyr at Bengal. The original pigment was only moderately durable. Now made in an alternative form by Winsor & Newton as a permanent colour.
Jaune Brillant. A reddish variety of Naples Yellow available in Artists’ Oil Colour.
Lemon Yellow. Originally barium chromate. Now substituted by either arylamide yellows or nickel titanate. The latter is a closer match to the original.
Naples Yellow. Originally lead antimoniate. Now supplied using a variety of pigments depending upon the range.
Nickel Titanate. Introduced by Winsor & Newton as a substitute for the original lemon yellow. Excellent low key semi-opaque yellow. First known in the 1960’s.
The greens, as much as any other colour, have benefited from the recent growth in pigment chemistry. Prior to the development of synthetic organic pigments, there were virtually no options for artists desiring a green of bright tonality in combination with strong tinting strength, good permanence, and low toxicity. Thanks to modern chemistry, new greens are available that offer all of those characteristics, while older green pigments have been made more stable while retaining much of their original historical character.
Cobalt Green. See under “Blues.”
Emerald Green. Originally made from arsenic, now made from phthalocyanine and others, depending upon the range.
Hooker’s Green. Originally a mixture of Gamboge and Prussian Blue. Later made from organic lakes. Now made from quinacridones and phthalocyanines.
Olive Green. Originally made from fugitive lakes, Olive Green is made from a variety of pigments, depending upon the range.
Oxide of Chromium. An extremely opaque, earthy green. Known as early as 1809. Listed by Winsor & Newton in the late 1840’s.
Phthalocyanine: See under “blues.”
Sap Green. Originally made from buckthorn berries, later made form organic lakes of moderate durability. Superseded by Permanent Sap Green.
Terre Verte. A natural earth, strengthened by oxide of chromium.
Viridian. A transparent blue green of lower tinting strength than phthalocyanine, and so preferred by many artists. First made in 1838, introduced in England in 1862.
Over the last two millennia, there have been blues available to the artist that offer rich hue, good tinting strength and covering power. But they’ve come at a high price, both in terms of cost and in effort to produce. From “smalt,” the first-ever compound of cobalt, used by the Egyptians in a ground glass form, to “Lapis lazuli,” the natural form of ultramarine dug from mines in present-day Afghanistan. Blues were considered a symbol of high status, not only for the painter that could afford to use them, but for the patron that could afford to own a painting that included the colour. Beginning in 1704, with the synthesis of Prussian Blue, and then in 1806, with the development of Cobalt Blue, and finally, in 1826, with the introduction of a laboratory-produced ultramarine that was identical to the natural lapis, blues became more affordable. And now, the availability of blues has grown exponentially with the introduction of phthalocyanine.
Antwerp Blue. A weaker variety of the very first laboratory synthesized (albeit accidentally) organic pigment, Prussian Blue.
Cerulean Blue. A type of cobalt. Introduced as early as 1805. Indispensable, semi-opaque, light blue of low tinting strength.
Cobalts. Blues, but also greens, violets, and yellows. Semi-transparent inorganic colours, excellent for tonal mixtures. Blue discovered by Thénard in 1804, redder variety (PB73) introduced by Winsor & Newton in the 1990’s. Violet introduced in 1860, green discovered in 1780, and yellow in 1862.
French Ultramarine. Invented by Guimet in France in 1826 in a competition to replace genuine lapis lazuli. It is chemically identical to the natural pigment. Winsor & Newton French Ultramarine has a red undertone.
Indanthrene Blue. A dark blue which is redder than phthalocyanine. Dye form discovered in 1901. Makes excellent darks mixed with umbers.
Indigo. Originally derived from the woad plant, Indigo was made synthetically in the 19th century but was not permanent. Now made from a mixture of ultramarine, phthalocyanine and black.
Manganese Blue. Now unavailable, a substitute is supplied made from phthalocyanine.
Phthalocyanines. Winsor Blues and Winsor Greens. First introduced in 1938. Lightfast and very high in tinting strength.
Prussian Blue. Marks the beginning of new synthetic organic pigments for modern painting. Discovered by Diesbach in 1704. Masstone is bronzy. Peculiar characteristic of fading in the light and recovering in the dark.
Ultramarine (Green shade). A greener shade of Ultramarine.
Another notable pigment is Tyrian purple, a colour demanded by Roman Emperors and that was squeezed from a cyst on the body of a whelk (a kind of mollusc). 12,000 molluscs were required to extract about 1.5 grams of colourant, boosting the cost of the colour into the astronomical range. But there was no other source for a rich, true purple, a situation that continued to some degree until the nineteenth century. Until the introduction of dioxazine in the1960’s, purples and violets either had to be mixed, or they were notorious for fading.
Caput Mortuum. A maroon Mars violet. Name originates from the 18th century.
Dioxazine. Deep violet supplied under its chemical name and Winsor Violet. Winsor & Newton tests show this colour to be permanent in oil, acrylic, and water colour. Introduced in the 1960’s.
Mauve. Made from a mixture of violet pigments.
Purple Lake/Madder. Originally synthesized alizarins. Now supplied using other lightfast pigments.
“Permanent” Colours. Organic pigments which replaced the first organics used in the 1920’s.
Winsor Colours. Transparent organic colours across the spectrum which have good lightfastness.
The stability of colour is more than just the inclusion of lightfast pigment. Permanence is also the stability of the paint film. At Winsor & Newton, we rate the permanence of our colours upon both factors: the lightfastness of the constituent pigment, as well as the proven stability of the overall formulation, including the vehicle.
The formal definition of the permanence of an artists’ colour is “its durability when laid with a brush on paper or canvas, graded appropriately and displayed under a glass frame, in a dry room, freely exposed to ordinary daylight and an ordinary town atmosphere.” This definition reflects the manner in which we expect to find paintings displayed.
For testing purposes, we are able to use accelerated tests for lightfastness and binder stability, in addition to the information issued by our pigment suppliers. Our ratings, therefore, are a combination of the natural passage of time, accelerated tests, and pigment manufacturers’ testing and development. Combined, these make up the most stringent tests in the industry.
(Our permanence ratings are as follows:)
AA – Extremely permanent
A – Permanent
B – Moderately durable
C – Fugitive
For further information on some colours the rating may include one or more of the following additions:
(i) “A” rated in full strength, may fade in thin washes.
(ii) Cannot be relied upon to withstand damp.
(iii) Bleached by acids, acidic atmospheres.
(iv) Fluctuating colour; fades in light, recovers in dark.
(v) Should not be prepared in pale tints with Flake White, as these will fade.
(vi) “A” rated with a coating of fixative.
It is worth noting that there are only three out of the 114 colours in the Artists’ Oil Colour range that have a permanence rating of less than A. Winsor & Newton continues to produce these colours because of their unique character, and because of continuing demand by artists. These colours are:
|Alternative if a permanent colour is required
Permanent Alizarin Crimson
Permanent Sap Green
|Alternative if a permanent colour is required
Permanent Alizarin Crimson
The American Society for Testing and Materials (ASTM) has set standards for the performance of art materials, include standards regarding lightfastness of colours.
To measure lightfastness using this system, colours are reduced to a level of 40% reflectance by the addition of Titanium White. “Reflectance” is defined by the amount of light reflected from the colour swatch. The swatches are then subjected to testing in both sunlight and artificially accelerated conditions.
The results allow each colour to be rated on a scale of I-V, depending upon the medium. In this system, I is the highest lightfastness available, though both ratings I and II are considered permanent for artists’ use. Where no ASTM rating is given for a Winsor & Newton colour, this usually indicates that the pigment or the type of range has not yet been tested by the ASTM. It does not automatically indicate a lack of lightfastness. In these cases, it is recommended that the Winsor & Newton permanence rating (listed upon the tube and within the colour literature) be used as an indication of the colour’s resistance to fading.
The artist can do a great deal to ensure the permanence of a material by using it with appropriate methods. The use of a poor quality ground, an unsuitable medium, or no final protection from dirt can lead to irreversible deterioration of an otherwise permanent material. Unreasonable expectations or unsound techniques can also lead to detrimental results. For example, using oil colours in very thick layers will result in a film that may well wrinkle or crack; or overthinning of colours with solvent can leave them underbound on the support, susceptible to damage and unsafe to varnish. It is a shocking fact that almost all problems relating to permanence or premature degradation of paintings stem from inappropriate technique, or the use of materials which are not manufactured specifically for the needs of artists and long-term durability. For further information on sound painting techniques, please refer to the section entitled “Applications, Techniques & Tips”
Just as rigorous standards are required in selecting pigments that will best meet the needs of the artist, so too, are binders and vehicles subjected to comprehensive testing before being selected for use in Winsor & Newton ranges.
The binder, or vehicle, for the colour serves three purposes:
Below is a listing of the binders and vehicles used in milling Winsor & Newton oil colours:
Linseed oil. Derived from the flax plant, linseed oil is the predominant vegetable oil used in Winsor & Newton colours. It produces a tough, stable paint film.
Safflower oil. Because of its paler colour, Safflower oil is used for the milling of many whites. Safflower oil dries more slowly, but may be intermixed safely with linseed oil.
Alkyd resin. Alkyds are made from a naturally derived oil and polymerized through a chemical reaction with an alcohol and an acid. The result is a resin-like substance that can be used as a vehicle for paint, or as an additive medium. As with linseed oil, alkyds dry by oxidation, as opposed to evaporation of the solvent (like acrylics).
Water mixable oil. For use as the vehicle with Artisan Water Mixable Oils, linseed oil and safflower oils have been chemically modified to accept water as a solvent. With that exception, the modified oil vehicles function as do a conventional oil, accepting water as a diluent agent in much the same way that linseed oil does with white (mineral) spirit, and then forming a stable film through oxidation.
Other additives. Whilst it is the goal of Winsor & Newton to create all colours within our ranges in the purest form possible, there are instances in which a superior colour can be produced through the inclusion of specific additives. For example, a particular pigment, when mixed with oil, may make a sticky, unusable paste. This stickiness can be alleviated, and a smooth, workable colour can be produced, by adding an appropriate wetting agent or stabilizer.
Producing the finest colour possible is more than creating an assemblage $of rough ingredients. Just as every pigment and vehicle is unique, each requires unique milling methods. The best way to understand the milling process is to follow it, step by step, through the mill…
Milling colour is an exacting process, requiring that every ingredient be carefully selected and balanced to ensure the best possible working characteristics.
Step one – Selection of the finest materials. This includes selection of pigments and binders according to the standards outlined in earlier sections.
Step two – Formulation. Every pigment accepts oil differently. Individual formulations are developed by expert chemists. Before milling begins, a clear understanding of the physical properties of the raw materials, and how to bring out the true qualities of the pigment are essential.
Step three – Mixing, the precursor to milling. Using an industrial mixer, pigment and oil are mixed together in readiness for actual milling.
Step four – Milling. Since the 19th century, a machine called a triple roll mill has been most commonly used for dispersing the pigment into an even suspension. As the name implies, the colour mixture passes between three large, heavy rollers (sometimes made of steel, sometimes of granite, depending upon the properties of the pigment), physically forcing the oil to “wet” the particles of pigment. The process is different for each pigment, often many passes through the mill are required to achieve complete dispersion.
Winsor & Newton mill its conventional oil colours to a fairly stiff viscosity to ensure complete retention of brush and knife strokes, and a surface free of levelling. There is also real advantage in offering stiff colour that can be easily adjusted by the artist to a more fluid, “juicy” viscosity through the addition of mediums. Conversely, it’s virtually impossible to bring colour that’s been milled to a soft viscosity safely back to a state of uniform stiff consistency.
Step five – Once the milling is complete, the colour must be evaluated in quality control. At Winsor & Newton, every batch is compared to previous batches. Each is tested for mass tone, undertone, viscosity and dispersion, to name but a few of the qualities that are evaluated. Through this method, we are able to ensure that our colours exhibit the optical and physical qualities that have been most desired by artists since the mid-nineteenth century. We also are able to ensure that recent improvements to the colour are added with consistency and uniformity.
This is the milling and testing procedure employed at Winsor & Newton. Only after the colour has been milled and tested to rigorous standards does it find its way into tubes or tins, and ultimately to the artists’ palette.