This is another superbly informative, crisply written and lavishly illustrated little book in The National Gallery’s A Closer Look series. To quote the blurb:

‘A Closer Look: Colour explores how painters apply colour, describes different types of pigments, and outlines optical theories and artists’ treatises. The authors explain the effect on colour of the artist’s chosen medium, such as oil, water or egg tempera, and the dramatic impact of new pigments.’

It ranges far and wide across the National Gallery’s vast collection of 2,300 art works, selecting 80 paintings which illustrate key aspects of colour, medium and design. The quality of the colour reproductions is really stunning – it’s worth having the book almost for these alone and for the brief but penetrating insights into a colour-related aspect of each one.

They include works by Seurat, Holbein the Younger, Corot, Duccio, David, Chardin, Ghirlandaio, Monet and Van Dyck in the first ten pages alone!

Aspects of colour

Colour quite obviously has been used by painters to depict the coloured world we see around us. But it has other functions, too. Maybe the two most obvious but easily overlooked are: to represent depth and create the optical illusion of three dimensions on a two dimensional surface; and to reinforce this by indicating sources of light.

Depth A common indication of depth is recreating the common observation that objects at a distance fade into a blue-ish haze. This is often seen in Renaissance paintings depicting increasingly hazy backdrops behind the various virgins and main figures. This is known as aerial perspective.

Light Sources of light need to be carefully calculated in a realistic painting. The book shows how the effect of light sources is achieved by showing glimmers of white paint on metallic objects or even on duller surfaces like wood. There is a particularly wondrous example in Lady Elizabeth Thimbelby and her Sister by Anthony Van Dyck. The authors give a close-up to show how the colour of the yellow dress worn by the main subject is reflected on the bare skin of of the little angel, and even in the catchlight in his right eye, an indication of the depth of thought which goes into his compositions.

• Detail of Lady Elizabeth Thimbelby and her Sister by Anthony van Dyck (1637)

Shadows turn out to be an entire subject in themselves. For centuries painters improved their depiction of shadows, at first using grey colours for the shadows of buildings, but quickly realising that the most shadowed things around us are fabrics. Dresses, cloaks all the paraphernalia of costume from the Middle Ages to the turn of the 20th century, involved reams of material which folded in infinite ways, all of them a challenge to the painters’ skill. At the very least, painting a fabric requires not one but three colours: the core colour of the fabric itself, the fabric in shadow, the fabric in highlight, reflecting the light source.

The human eye is not a mechanical reproducer of the world around us. It has physiological quirks and limitations. The book evidences the way that, dazzled by orange sunsets, the human eye might well see evening shadows as violet. Quirks and oddities like this were known to various painters of the past but it was the Impressionists who, as a group, set out to try and capture not what the rational mind knew to be the colour, but the colours as actually perceived by the imperfect eye and misleadable mind.

Emotion In the later 19th century artists across Europe made the discovery that intensity of colour can be used to reflect intensity of emotion. Probably the most popular painter to do this was van Gogh whose intense colours were intended to convey his own personal anguish. This approach went on to become the central technique of the German Expressionist painters (although they aren’t represented in the book, along with all 20th century art, because the National Gallery’s cut-off point is 1900).

Symbolism In earlier centuries, more than its realistic function, colour had an important role in a painting’s symbolism i.e. certain colours are understood to have certain meanings or to be associated with certain people or qualities. The most obvious period is the Renaissance, when the Virgin Mary’s cloak was blue, Mary Magdalene’s cloak was red, St Peter’s cloak was yellow and blue, and so on. From early on this allowed or encouraged Renaissance painters to create compositions designed not only to show a (religious) subject, but to create harmonious visual ‘rhythms’ and ‘assonances’ based on these traditionally understood colour associations.

Pigments and Media

This is dealt with quite thoroughly in another book in the series, Techniques of Painting. There we learn that paint has two components, the binding medium and the pigment. Over the centuries different pigments have been used, mixed into different binding mediums, including egg, egg yolks, oil, painting directly into wet plaster (fresco) and so on.

Painting is done onto supports – onto walls, plaster, or onto boards, metal, canvas or other fabrics. All of these need preparing by stretching (canvas) or smoothing (wood), then applying a ground – or background layer of paint – to soak into the support. Painters of the 14th and 15th centuries used a white ground. In the 16th, 17th and 18th centuries, artists experimented with varying the tone of the ground, which significantly alters the colour of the works painted onto them.

Hardening Binding mediums dry out in two ways: watercolours and synthetic resin paints by simple evaporation. Drying oils such as linseed, walnut or poppy oil harden by chemical reaction with the oxygen in the air. Egg tempera, used extensively in the 14th and 15th century, dries by a combination of both.

This may sound fairly academic but it profoundly affects the whole style and look of a painting. Because tempera dries so quickly (especially in hot, dry Italy) shapes and textures are best built up by short hatched strokes.

This is a detail from the Wilton Diptych (1397) where you can see the way the skin of the Virgin and child and angels has been created by multiple short paint strokes of egg tempera.

Whereas, because oils are slow drying, they allow the artist to merge them into smooth, flowing, continuous transitions of colour. Oil paints = more flowing.

In this detail from Belshazzar’s Feast by Rembrandt, you can see how the gold chain has been rendered with a really thick layer of gold paint. Laying on very thick layers of oil paint is called impasto.

In general, oil paint looks darker and richer than paint made using water-based media such as egg tempera, glue or fresco, which appear lighter and brighter.

Age and decay Painting was, then, a highly technical undertaking, requiring the painter to have an excellent knowledge of a wide range of materials and chemical substances. Different media dry and set in different ways. Different pigments hold their colour – or fade – over time. And this fading can reveal the ground painted underneath.

One of the most interesting aspects of the book is the specific examples it gives of how some pigments have faded or disappeared – sometimes quite drastically – in Old Master paintings.

In Duccio’s The Virgin and Child with Saints Dominic and Aurea, the face and hands of the figures show clearly how the lighter pigments painted in tempera have faded or flaked off allowing the green underpaint to come through. The Virgin was not meant to look green!

Bladders to tubes Pigments had to be ground by hand and mixed in with binders in studios for the medieval and Renaissance period. There are numerous prints showing a Renaissance artist’s studio for what it was, the small-scale manufactory of a craftsman employing a number of assistants and making money by taking on a number of students.

In the 18th century ready-mixed pigments could be transported inside pigs’ bladders. The early 19th century developed the use of glass or metal syringes. But it was in 1841 that an American, John Rand, developed the collapsible metal tube. This marked a breakthrough in the portability of oil paints, allowing artists to paint out of doors for the first time. A generation later a new school arose – the Impressionists – who did just this. Jean Renoir quotes his father, the painter Pierre-Auguste, as saying:

Without paints in tubes there would have been no Cézanne, no Monet, no Sisley or Pissarro, nothing of what the journalists were later to call Impressionism.

Biographies of colours

Primo Levi wrote a classic collection of short stories based on The Periodic Table of chemical elements. It crossed my mind, reading this book, that something similar could be attempted with the numerous pigments which artists have used down the ages.

This book gives a potted history of the half a dozen key colours. It explains how they were originally produced, how different sources became available over the centuries, and how the 19th century saw an explosion in the chemical industry which led to the development of modern, industrially-manufactured colours.

Blue

• Prime source of blue was the ultramarine colour extracted from the mineral lapis lazuli, which was mined in one location in Afghanistan and traded to the Mediterranean.
• A cheaper alternative was azurite, which was mined in Europe but had to be ground coarsely to keep its colour, and is also prone to fade into green, e.g. the sky in Christ taking Leave of his Mother by Albrecht Altdorfer (1520). Many artists painted a basic wash of azurite and then used the much more expensive ultramarine to create more intense highlights.
• Indigo is a dye extracted from plants. At high intensity it is an inky black-blue, but at a lesser intensity also risks fading.
• A cheaper alternative was smalt, manufactured by adding cobalt oxide to molten glass, cooling and grinding it to powder. It holds its colour badly and fades to grey.
• In the early 1700s German manufacturers stumbled across the intense synthetic pigment which became known as Prussian blue (the book gives examples by Gainsborough and Canaletto).
• Around 1803 cobalt blue was invented.
• In 1828 an artificial version of ultramarine was created in France

Thus the painters of the 19th century had a much wider range of ‘blues’ to choose from than all their predecessors.

The book does the same for the other major colours, naming and explaining the origin of their main types or sources:

Green

• Terre verte was used as an underpaint for flesh tones in early Italian paintings
• malachite
• verdigris, a copper-based pigment was prone to fade to brown and explains why so many Italian landscapes have the same orangey-brown appearance
• emerald green (a pigment developed in the 19th century containing copper and arsenic)
• viridian (a chromium oxide)

Red

• Vermilion, obtained by pulverising cinnabar, liable to fade to brown as has happened with the coat of Gainsborough’s Dr Ralph Schomberg (1770), which should be bright red.

Yellow

• Lead-tin yellow in the Renaissance
• from the 17th century lead-based yellow containing antimony known as Naples yellow
• from the 1820s new tints of yellow became available based on compounds of chromium of which chrome yellow is the most famous
• cadmium yellow

White

• Lead white was used from the earliest times. It forms as a crust on metallic lead exposed to acetic acid from sour wine – highly poisonous
• only in the twentieth century was it replaced by non-toxic whites based on zinc and later, titanium. Unlike all the pigments named so far, lead white keeps its colour extremely well, hence the bright white ruffs and dresses in paintings even when a lot of the brighter colour has gone.

Black 

• A large range of black pigments was always available, most based on carbon as found in charcoal, soot and so on. Carbon is very stable and so blacks have tended to remain black.

Summary of colours

1. Over the past 500 years there has been a large amount of evolution and change in the source of the pigments artists use.
2. Colour in art is a surprisingly technical subject, which quite quickly requires a serious knowledge of inorganic chemistry and, from the 19th century, is linked to the development of industrial processes.
3. Sic transit gloria mundi or, more precisely, Sic transit gloria artis. The net effect of seeing so many beautiful paintings in which the original colour has faded – sometimes completely – can’t help but make you sad. We live among the wrecks or decay of thousands of once-gloriously coloured artworks. Given the super-duper state of digital technology I wonder if anywhere there exists a project to restore all these faded glories to how they should look!

Disegno versus colore

Vasari, author of The Lives of the Great Artists (155) posed the question, ‘Which was more important, design or colour?’ As a devotee of Michelangelo, the godfather of design, he was on the side of disegno and relates a conversation with Michelangelo about some paintings by Titian (1488-1576) they had seen where Michelangelo praises Titian’s use of colour but laments his poor composition.

The art history stereotype has it that Renaissance Florence was the home of design, while Venice (where Titian lived and worked) put the emphasis on gorgeous colours. This was because Venice was a European centre for the production of dyes and pigments for a wide range of manufacturing purposes, not least glass and textiles.

In late-17th-century France the argument was fought out in the French Academy between Rubénistes (for colour) and Poussinistes (for drawing). Personally, I am more moved by drawing than colour, and a little more so after reading this book and realising just how catastrophically colour can fade and disappear – but, still, there’s no reason not to love both.

Optical theories

Isaac Newton published his Optics in 1704, announcing the discovery that when white light is projected through a prism it breaks down into primary colours, which can then be turned back into white light. Among its far-ranging investigations, the book contained the first schematic arrangement of colours and their ‘opposites’. It wasn’t until well into the 19th century, however, that colour charts began to proliferate (partly because they were required by expanding industrial manufacture, and the evermore competitive design and coloration of products).

And these colour charts bore out Newton’s insight that complementary colours – colours opposite each other on the circle – accentuate and bring each other out.

Colour Circle by Michel Eugène Chevreul (1839)

Colour circles like this systematised knowledge which had been scattered among various artists and critics over the ages. It can be shown that Eugène Delacroix (1798-1863) made systematic use of contrast effects, pairing colour opposites like orange-blue, red-green or yellow-violet, to create stronger visual effects.

On a simplistic level it was the availability of a) new, intense colours, in portable tin tubes, along with b) exciting new theories of colour, which explains the Impressionist movement.

The Impressionists were most interested in trying to capture the changing quality of light, but the corollary of this was a fascination with shadow. Apparently, impressionist painters so regularly (and controversially) paired bright yellow sunlight with the peculiar tinge of violet which is opposite it on the colour charts, that they were accused by contemporary critics of violettomani.

Some examples

The book lists the pigments used to create Titian’s Bacchus and Ariadne. The intense blue sky is made from ultramarine lapis lazuli, as is Ariadne’s drapery and the flowers at the lower right. The blue-green sea is painted with the cheaper azurite. Vermilion gives Ariadne’s sash its red colour. The Bacchante’s orange drapery was painted with a rare arsenic-containing mineral known as realgar.

Titian was aware of the power of colour contrasts long before the 19th century colour wheels, something he demonstrates by placing Ariadne’s red and blue drapery above the primrose yellow cloth by the knocked-over urn at her feet (painted using lead-tin yellow). The green of the tree leaves and the grassy background are created from malachite over-painted with green resinous glazes. An intense red ‘lake’ is used to give Bacchus’s red cloak its depth.

These coloured ‘lakes’ were an important element in Renaissance painting but I had to supplement the book’s information with other sources.

• Lake paints Wikipedia article

From this I take it that ‘lakes’ were translucent i.e. you could see the colour beneath, and so were used as glazes, meaning you would lay down a wash of one colour and then paint over potentially numerous ‘lakes’ to add highlights, depths or whatever. This build-up of ‘lake’ glazes allowed the layering of multiple variations of colour and so the intensely sensual depiction of the folds on fabrics, the light and shade of curtains and clothes which is so characteristic of Old Master painting.

The book then applies this detailed analysis of colour pigments to a sequence of other Old Masterpieces by Rubens, Velázquez, Rembrandt, Tiepollo, Canaletto, Monet and Seurat.

Conclusion

A Closer Look: Colour makes you appreciate the immense amount of knowledge, science, craft and technique which went into painting each and every one of the National Gallery’s 2,300 artworks (and the depth of scholarship which modern art historians require to analyse and unravel the technical background to each and every painting).

It’s a revelation to read, but also pure joy to be prompted to look, and look again, in closer and closer detail, at so many wonderful paintings.

Related links

• A Closer Look: Colour on Amazon
• A Closer Look: Techniques of Painting by Jo Kirby (2011)
• The National Gallery Glossary

Reviews of National Gallery exhibitions

• Lake Keitele: A Vision of Finland (December 2017)
• Drawn in Colour: Degas from the Burrell (December 2017)
• Monochrome (December 2017)
• Michelangelo and Sebastiano (March 2017)
• Australia’s Impressionists (January 2017)
• Beyond Caravaggio (December 2016)
• Painters’ Paintings: From Freud to Van Dyck (August 2016)
• Delacroix and the Rise of Modern Art (February 2016)
• Every room in the National Gallery (December 2015)
• Goya: The Portraits (November 2015)
• Inventing Impressionism (May 2015)
• Making Colour (September 2014)
• Veronese (May 2014)
• Facing the Modern: The Portrait in Vienna 1900 (January 2014)