Pigments are the raw materials of painting and art. They are insoluble particles that impart colour and some degree of hiding power over the surface to which they are applied.1 Pigments, and advances in their technology, have influenced the development and history of Western art since its earliest forms. Pigment creation has been paralleled to some extent by the development of paints and binders into which the pigments could be dispersed. This paper reviews the history of art from the perspective of the pigments used to create that art and the development and influence of science and technology in art. It is not intended to be an exhaustive review of every pigment ever used for this purpose but aims to cover the most important and interesting colorants and to give the reader a taste of the long history of pigments. Chemical information on many of the inorganic pigments is given in Table 1.

Prehistoric Art

The earliest examples of art date from around 40,000 BC in the form of cave paintings.2-4 Primitive man tried to represent aspects of his environment in paintings or carvings, and these often depicted deer or bison, which were hunted for food.5,6 These images appear to have been created in a ritual way, many being overlaid one upon the other, possibly with the belief that primitive man could somehow gain power over his quarry by means of these representations. Good examples of such European Paleolithic art can be found in Lascaux in Southern France.7-11 These cave paintings have been carbon dated at around 15,000 BC.12,13

Primitive Pigments
Primitive man used pigments from his natural environment in painting, thus the pigments found in different areas of the world tend to vary.14 It is thought that pigments were applied by two methods.2,15 The first was to mix pigment with animal fat and apply it as a paint with the fingers or a reed. The second method was to blow pigment powder onto the painting surface using a hollow tube.

Carbon black was usually found in the form of soot obtained from charred bones or wood, or charcoal from the wood itself, which could be used for drawing. Yellow and red earths were iron oxides in various states of hydration.16 These substances occur naturally throughout the earth's crust, so were probably used by all primitive people, and synthetic forms of yellow and red ochre are still used today. Brown earth was a mixture of iron and manganese oxides, again occurring in all parts of the earth. The shade of these brown earths could vary from red brown to almost purple, depending on the purity and exact oxide content.16,17 Green earth came primarily from two clay minerals, celadonite and glauconite.18 These have a complex silicate structure containing aluminium, iron, magnesium and potassium ions, which give a dull green colour. It was used less frequently than the other primitive pigments due to its relative scarcity. White pigments were obtained from chalk (calcium carbonate), and from crushing up animal bones (essentially calcium phosphate). The palette of the primitive artist was thus quite limited and contained only dull, earthy shades.

The Egyptian Dynasties

Egypt had the longest unified history of any civilization in ancient times and this extended from around 4000 BC to 300 AD, with a style of art that remained unchanged for nearly as long. At the start of this period, ancient Nile dwellers developed from hunters into agriculturists and formed early settlements. Chieftains of these tribes began to unite, and by 3100 BC the rule of Egypt was unified by the first pharaoh, Narmer.19 The earliest art work, pottery and hieroglyphs date from that period. From 3100 BC Egypt was ruled by a pharaoh who was considered to be a divine ruler by his subjects.20 The Egyptians believed in the afterlife and that the body should be preserved by mummification in order that the soul should live on. The likeness of a person was also preserved in writing, painting and sculpture. Painting and art followed very strict rules because they were not designed for enjoyment, but rather to perform the very serious task of preserving a person into the afterlife.21,22 The painting of ancient Egypt appears strange, it is angular and distorted, but Egyptian artists were merely trying to represent everything as it best looked. The human body was always painted the same way - the head was always shown in profile, while the eyes were shown from a frontal view.23 The torso was always shown from the front, while the limbs were represented from the side to preserve their movement. Feet were always shown from the big toe side, so Egyptians always appear to have two left feet.

The culture of ancient Egypt was very advanced in many respects. The pyramids and temples are testament to their architectural and engineering skills, but also illustrate the organization of Egyptian society.24 Most modern knowledge of this society comes from the relics, paintings and hieroglyphs found in tombs of the pharaohs and of other important nobles.25 Every aspect of life was recreated inside the tombs for the pharaoh to take with him to the afterlife. This left a clear record for archaeologists.

Egyptian Pigments
The important role of art in Egyptian life meant that a variety of new pigments were added to the prehistoric palette, including brighter pigments, and even the first manufactured pigments.26

Natural pigments introduced by the Egyptians included malachite, azurite, cinnabar, orpiment and lapis lazuli.17,27 Malachite and azurite are deep green and blue minerals that occur in close proximity to each other. They are both basic copper carbonates that can be ground and washed to give good green and blue pigments. Cinnabar is a bright red mineral that, when crushed, provides an opaque, bright red pigment.16 It is a naturally occurring mercuric sulphide and was the first bright red pigment available to the early artist, although it is prone to darkening on exposure to light. Orpiment, a bright golden yellow mineral imported from Syria16, is a natural arsenic sulphide that is toxic, giving off poisonous fumes and a bad smell. This does not appear to have reduced its usage as a pigment, probably because it was the only bright yellow available. Lapis lazuli, a member of the sodalite group, is a blue mineral occurring in mountainous regions.16 The mineral is a deep blue colour, often flecked with gold from iron pyrites and grey silicates, which make the colour less pure. Lapis lazuli was crushed and used as a durable, intense blue pigment, but was also widely employed in jewelry and sculpture by the ancient Egyptians who valued it very highly indeed, making it the most expensive pigment in the artist's palette.28,29

The first blue pigment manufactured by the Egyptians was blue glass, or smalt.16,30 It was introduced in about 2500 BC and was made by heating sand with copper metal, copper ore and alkali, although cobalt was also probably used to produce the blue colour. The resulting glasses were used in decoration of sculptures and in jewelry, as well as being artists' pigments.

Many early dyes were discovered by the ancient Egyptians, such as blue woad (Isatis tinctoria), indigo (Indigofera) and red madder (Rubia tinctorum), which all came from plants, and red carmine, which was produced from the kermes beetle.31,32 These dyes were converted into pigments by making lakes, a technology pioneered by the early Egyptians. Laking is the precipitation of a dye onto particles of an insoluble, colourless binder such as chalk or white clay. The Egyptians may have also produced lakes by complexing the dye molecules with metal salts such as aluminum from alum.

Woad and indigo were extracted from the leaves of their respective plants with hot water, and the laked pigments were made by scraping off the foam that formed on top of the extraction vessel. This foam was ground with chalk or some other binder to give a blue powder, which could be dried and used as a pigment.33 Madder was cultivated by the Egyptians.34 Dyes ranging in colour from pink to red, brown and purple were extracted from the root of the plant by an aqueous filtration process. The dried ground roots were mixed with water and treated in a series of stages with alkali, then filtered through meshes to extract the colouring matter. The red dye was converted into a lake pigment by precipitation onto a binder, although it is not clear whether the Egyptians actually used madder lake as a pigment.

Carmine, a red colorant mentioned in the Old Testament and by Pliny,35-37 was probably first used as a lake pigment as early as Egyptian times. It was obtained from the kermes beetle, which is native to Europe and Asia, and found on various types of oak trees.37 The female insect attached itself to the oak tree to lay eggs, and then both were collected just before hatching and killed with vinegar. The colour was extracted by pouring boiling water onto the dried insects to release the water soluble kermesic acid, which was then precipitated with iron-free alum to give an insoluble lake pigment.38

Painting Methods
The palette of the ancient Egyptian artist was considerably wider than in prehistoric times, but the Egyptians also created new methods of painting and applying colour to the tombs and walls they wished to decorate.1

The ancient Egyptians, Minoans and Cretans all used fresco as a painting style, and this was probably invented either by the Egyptians or Babylonians before them.39 The technique of fresco is to paint onto lime plaster while it is still wet, or fresh.40 A sketch is drawn onto the penultimate layer of plaster, and design outlines are marked with dark paint wash. Then a fresh layer of plaster is applied over the top of the design in small sections, which are then painted.41 As the plaster begins to dry there is a reaction between the lime and air to form calcium carbonate, which causes a chalky film to form over the colorants. Fresco colours are very clear but have a slightly filmy, transparent appearance. The technique is very durable, and many examples are still found in Egyptian tombs.24,26 Pigments used for fresco were prepared by dispersing the powders in water and a natural, water soluble binder, such as gum arabic, which is a tree gum. The mixture was then applied with a brush to the wet plaster and was somewhat akin to the modern watercolour paint.1,27 The Egyptians also used watercolour-style paints to create papyrus illustrations and hieroglyphics, but unfortunately very few of these survive.

Later the Egyptians began to use a new medium called encaustic painting.42 This term comes from the Greek enkaustikos, meaning to burn in. Pigments were mixed with beeswax and a resin and then heated to soften them. The warm, soft, coloured mass was then applied to the painting surface and burned in with a palette knife heated in a charcoal burner. Encaustic gave a hard, brilliantly coloured, durable finish, but unfortunately was particularly susceptible to water damage, so very little Egyptian encaustic survives.

Another very ancient painting technique was that of tempera1,41, which was probably developed by the Babylonians and passed down to the Egyptians. In traditional tempera painting the pigment is carried in a medium of egg yolk, to which some vinegar may have been added. The paint was then applied with a brush, but had to be worked quickly as it dried fast. Tempera paints in Egyptian times were usually coated onto plaster, and surviving examples tend to be tomb paintings. Egg yolk is a natural emulsion of water, oil and lecithin, which dries very quickly, giving a matt appearance, and thus the tempera paint was really the distant relative of the modern emulsion paint. The yellow colour of the egg yolk was due to a carotenoid and did not affect the colour of the paint since it was quickly bleached by sunlight.

Ancient Greece

The Egyptian dynasties spanned an enormous age of history and influenced many other cultures and people but perhaps none more so than the society of ancient Greece. The Greeks particularly learned the lessons of art from Egypt and then built upon them to create a great artistic tradition of their own.

As Egypt became more open to the outside world in about 500 BC, the styles of art were seen more frequently in its neighbours, particularly on the island of Crete, which had a very advanced culture of its own. These ancient Cretans were actually the original classical Greeks, about whom very little is known.43 In about 1000 BC the ancient Greek civilization was invaded by warlike tribes from Europe, which precipitated great conflicts, some of which are recounted in the Homeric tales. The art and architecture of these new hybrid Greeks was initially primitive and rough, but in about 600 BC a shift occurred and these people began to build in stone and start a civilization of their own.44 Where the Egyptians built colossal temples reflecting the fact that they had just one divine ruler, the Greeks built smaller structures reflecting the lack of one supreme deity or ruler.45

The real revolution in Greek art took place in the city-state of Athens where philosophy, theater, politics and many other forms of expression were developed. These new Greek artists began where the Egyptians had left off, but they began to use their eyes rather than simply to follow a formula. Surviving paintings from around 600 BC (mostly in the form of pottery) show the Egyptian style being faithfully copied, but by around the fifth century BC the style had changed considerably. This Greek era gave us the first example of a foot being painted from the front view.46 Although this sounds like such a small achievement, nothing of the kind had occurred in the previous 40,000 years of art history: it was a total revolution!

Greek art flourished but still used the Egyptian rules to some extent; clear outlines and knowledge of human anatomy were very much in evidence, but the old rules were no longer sacred. In 480 BC the temple of the Acropolis, which had been destroyed by Persians, was rebuilt in marble, and many great works of art were commissioned to adorn it.47 Unfortunately very few of these works have survived because most of them were destroyed by Christians later in history, who considered it a religious duty to smash all ‘graven idols'. The sculptures we do have are generally copies made by Roman art collectors;48 these statues, although beautiful, have tended to give the impression that Greek art was lifeless and cold, and portrayed people with vacant eyes looking slightly chalky. Nothing could actually be further from reality because the original statues were often made in bronze or wood being over 10 m high and were painted with bright colours and decorated with gemstones. The eyes of sculptures were created from precious stones and minerals to give the figures a lifelike image.

The time between 520 BC and 420 BC was one of newfound artistic freedom in Greece where people began to be interested in art for its own sake.49 They began to collect art and criticize it, comparing various styles and works. The human body was portrayed with greater fluidity, and the Greek artists no longer had trouble representing motion as the Egyptians had done. Greeks of this era did not use real human beings as models for their sculpture or painting, rather they used the Egyptian rules of creating the perfect human from their knowledge of anatomy. No human being alive was ever as perfect as a Greek representation of the 4th century BC. It was not until later in Greek history, under the rule of Alexander the Great, that the concept of an individual portrait was devised.50

Hellenistic Art
Alexander founded the Hellenistic empire, which ruled over many countries to the east of Greece, and the Hellenistic art of this era took account of these Eastern styles to produce a blend of flamboyant, free flowing art that was full of movement.51 Many paintings of this time have survived and they seem to be more realistic than anything seen before, but if studied carefully, the rules of Egypt were still very much in evidence.52 Art showed everything depicted very carefully and accurately, but from the knowledge of the artist rather than from reality.

Pigments of the Greeks
The Greeks inherited the painting palette from the Egyptians but soon started to create an entirely new group of pigments, inventing methods for making some of the natural pigments for themselves. Painting styles of fresco, encaustic, tempera and watercolour continued to be used in Greek art but incorporated some new pigments into the palette. To the existing natural pigments the Greeks may have made a number of additions of sepia, gold and crysocolla. As with all natural pigments, it is difficult to pinpoint exactly when they began to be used, and indeed some or all of them may well have been used by the ancient Egyptians or even Babylonians.

The transparent dark brown sepia was obtained from the cuttlefish or octopus found in the Adriatic and Mediterranean seas.53 The octopus squirts dark ink as a defensive measure54, and this ink was used as a watercolour or fresco paint. The ink sacs were removed from these creatures after they had been caught by fishermen; they were then dried and ground up for use as a pigment. In later times the colouring matter was purified for use by regrinding it with alkali, then filtering and neutralizing with acid to precipitate the brown pigment, which was washed and dried.

Crysocolla is a natural green copper silicate that can be used as a pigment.18 It was used by the Greeks as an adhesive for gold as well as functioning as a pigment.16 The name crysocolla literally means ‘gold glue' in Greek. Like green earth, it is a mixture of iron, magnesium, aluminium and potassium salts, which occur naturally all over the world.55,56 Gold was widely used by the Greeks for adorning their statues and temples, and likewise for the Egyptians, but it was also ground up and used as a pigment.16 Owing to its high price and rarity, it seems likely that gold pigment would have been reserved for the most important and sacred works of art.

In addition to these new natural pigments, the Greeks introduced a group of new artificial pigments, some of which are still in use today, including white lead, red lead, yellow lead, verdigris and red vermilion. Very few actual paintings from ancient Greece survived, and most of the knowledge of pigments comes from writings of the time, which often recorded manufacturing processes in great detail. The Greeks began the trend for manufacturing pigments that has continued to this day.

White lead is basic lead carbonate and is a very superior white pigment when compared with chalk and crushed bones16. It was in constant use until the advent of titanium dioxide in the 20th century, and is still now used in oil painting.30 The Greeks produced white lead by a stack process, described in detail by Pliny57, and was still used in relatively modern times by the Dutch. The stack process involved placing strips of lead in clay pots suspended on racks above vinegar.16 Many such pots were stored together in a small building, and the gaps between the pots were filled with animal dung. The building was then sealed up for a period of about three months, during which time the action of the acetic acid, oxygen and carbon dioxide produced in fermentation of the animal dung formed basic lead carbonate on the surface of the lead strips. The white lead was removed by scraping it off the lead, and then the pigment was ground ready for use.

Red lead18 was manufactured using a process that also produced another pigment, the yellow lead monoxide known as massicot.58 This process was also described by Pliny and involved the continuous stirring of molten lead in an open furnace for about five hours.57 During this time of constant heating, the lead was oxidized to form a yellowish grey powder, which was subsequently milled, ground and washed in water to separate the yellow massicot from the metallic lead.59 The lead sank to the bottom of the washing vessel while the yellow pigment was dispersed in the water, and this could be decanted off and then evaporated to obtain the dry massicot. Yellow lead monoxide is not actually a very good pigment in itself, and its main use was as an intermediate in the production of red lead. The pigment red lead is a darkish, dull red that has very durable properties as a pigment60; it is still used today in protective paint finishes for metal coatings.

Verdigris was a green pigment (basic copper acetate) prepared by the Greeks from copper and wine vinegar, and again described in detail by Pliny.57,61 It has been widely used throughout Europe for many centuries, the name coming from French, meaning green of Greece.16 It was manufactured by pouring sour red wine into an earthenware pot at a depth of several inches, then placing copper plates onto a grille above the wine. The copper plates were stacked up in layers with grape stalks, which allowed the acidic wine fumes to circulate inside the vessel after it was sealed up for a week or so. The copper plates were then turned and exposed to the acidic fumes again for another few days, after which they were removed from the vessel. The plates were sprinkled with wine vinegar and pressed under weights for some time. This process caused the formation of green matter on the surface of the copper that could be scraped off, dried and molded into blocks for use as a pigment. Verdigris produced by this method was quite crude and often gritty. Later in history it was refined and purified by artists before use to improve its pigment properties.

The vivid, bright red pigment vermilion was artificially prepared mercuric sulphide introduced to replace cinnabar, although both the natural and artificial pigments were in use in ancient Greece.18 The preparation method of vermilion was developed by Eastern alchemists and mystics, and was unknown in the West until medieval times.62 A mixture of mercury and sulphur were heated together in a flask with a narrow neck, and when the mercuric sulphide formed it sublimed and then condensed at the top of the flask around the neck. The reaction flasks had to be broken in order to allow removal of the vermilion, which could then be prepared for use as a pigment by grinding. Vermilion produced by this method was initially black and the red colour developed on repeated grinding.16

Roman Empire

After the decline of the Hellenic empire came the Roman civilization, which based all its art and culture on the ruins of Greece.63 The Romans were not particularly noted for their artistic achievements but, as mentioned earlier, were fond of Greek art and frequently commissioned copies of Greek masterpieces.64 The great achievements of the Romans stood in the fields of civil engineering, architecture and the organization of their society. Art was used in a decorative manner in Roman times, as archaeological evidence from places such as Pompeii testifies, but more interestingly it was also used for purposes of propaganda.65 Many of the conquests and military campaigns of the emperors were recorded in carvings or relief to act as an early version of war correspondence. The most common form of Roman art that we see today was the sculptures and busts of the emperors and other important dignitaries.66 These retained the grace and harmony of the Greek sculptures but were actually portraying real people rather than an image of perfection.

Dark Ages

As the Roman Empire began to decline, many of the skills of artists learned from the great Greek masters were lost and a whole new artistic scenario swept through Europe on the uprising tide of Christianity. The rise of Christianity in Europe occurred during the Dark Ages67,68, so called because of the scarcity of factual information about these times. The Dark Ages lasted roughly from about 500 AD to 1000 AD, and many changes took place during this time; they were marked with wars, upheavals and invasions by the tribes of northern Europe such as the Goths, Vandals, Saxons and Vikings. Much of the learning of Greek times was lost, and many artistic treasures were destroyed, although the mixing of European peoples brought a great influx of new styles and traditions together that helped to create an entirely new style of Western European art.69 New medieval art began to emerge from a blend of religious icons created by the early Christian church, and traditional craft works. The new art began to express feelings and religious events often at the expense of accuracy and classical beauty.70

Very few technical advances in artists' materials were made during the Dark Ages or medieval times, but new methods of creating art were developed. A strict system of training for artists was in operation and this consisted of young boys being apprenticed to a painting master until they were accomplished enough to become masters in their own right. These schools of painting were run like guilds of craftsmen, and in fact painters and artists were treated like any other craftsmen practicing a trade71, being trained to paint according to a particular formula. Most commissions for painting came from the Church68, so the vast majority of artistic work was created for religious purposes. The individual artists were considered relatively unimportant compared with the works they undertook. During this time France became the strongest country in Europe, with Paris being regarded as the cultural and artistic center.72 Many architectural and artistic developments took place in Paris up to the 13th century, including the development of the Gothic style.

The Early Renaissance

During the medieval period of European history the artists of Italy began to follow a slightly different route than those in the rest of Europe; this ultimately led to the complete revolution in art known as the Renaissance. This new period of Italian art began at the turn of the 13th century, and one of the artists responsible was the Florentine painter Giotto di Bondone (1267-1337)73,74, who was famed for the creation of frescos in a church at Padua, completed between 1302 and 1305. Giotto's frescos show depth, with the figures in them being depicted realistically, in a completely new manner for art of the time. Giotto began a long tradition of drawing from nature and also of beginning to explore the laws of vision used in painting. After the time of Giotto, artists began to be judged on their skill at depicting things realistically, and this revolution led directly to the Italian Renaissance.75

The word renaissance means rebirth or revival, and in Italy this came to be known as the revival of art from the classical Greek era and was also associated with reviving the grandeur of Rome. The Renaissance was led from Florence and encompassed the fields of art, architecture, science and literature; it was truly a golden time for discovery of the new and unknown.76 These various disciplines combined to give the discovery of perspective, which was a completely new concept in painting.77 Perspective is something taken completely for granted today, being taught in school art classes, but in the 14th and 15th centuries perspective was a completely novel idea, which was explored and investigated with fervour. Human models were employed by artists for the first time. Works of the Italian sculptor Donatello (1386-1466) well illustrate the advances made in the Renaissance at representing the living human form with grace, movement and realism.78,79

Italians of the Middle Ages and Renaissance did not only advance art but also introduced new pigments to the artist's palette. Their most important discovery was a method for extracting the brilliant blue pigment ultramarine from the blue mineral lapis lazuli16, which contains about 10% ultramarine. One method of extraction was to grind up the mineral into a fine powder and mix it into a dough with beeswax and resin. This waxy dough was kneaded in a bowl of water, which facilitated the blue pigment being released into the water while the grey minerals were retained in the wax. Kneading was repeated in several bowls of water to remove all of the ultramarine. The best quality of ultramarine with a bright, blue violet hue was released into the water first and as the kneading process continued the colour of ultramarine obtained became greyish. Natural ultramarine was a highly prized pigment in Renaissance times and was often reserved for painting of the Virgin's mantle in religious scenes due to its high cost.80 The blue pigment had superior qualities in terms of colour, tinting strength and durability, and it continued to be the most expensive pigment until the advent of synthetically produced ultramarine. Natural ultramarine is still produced in small quantities for artists today by a very similar method to that used in the Renaissance.

Yellow and Brown Pigments
Another pigment introduced by the Italians of the Renaissance was Naples yellow16, a natural pigment found on the slopes of Mount Vesuvius, but later artificially made by a method described by Piccolpasso between 1556 and 1559. The pigment lead tin yellow was also introduced some time in this period, which can be prepared in a range of tones from lemon to deep yellow.16,81

Coloured earths were exploited and developed by the Italians, and indeed most earth colours are still known by their Italian names.82 Umber, a brown pigment, is a mixture of iron and magnesium oxides, the name coming from the Italian ‘ombra' meaning shadow, relating to its function of painting shadows. Umber was used raw or was roasted to achieve a deep red brown colour known as burnt umber, which was favoured by artists.

Sienna was another natural earth pigment, its yellow-brown colour being attributable to a mixture of hydrous oxides of iron and manganese. Sienna could be used raw or after roasting in air to achieve a dark brown colour called burnt sienna.

Imported Pigments
The Italians also advanced manufacture of lake pigments, developing natural pigments from Indian lac, carmine and brazil wood.17 Unfortunately these natural pigments tend not to be very fast to light and are not frequently used today.

The Spanish conquest of the Mexican and Aztec civilizations of South America in the 16th century yielded the discovery of carminic acid produced by a female cochineal shield louse (Dactylopius coccus). This red colorant was imported into Europe in the form of the dried powdered insects. Cochineal quickly superseded kermes for reds because of its wider availability and stronger tinctorial strength. It was widely used to manufacture lake pigments, some of which are still employed today in cosmetics such as lipstick and nail varnish. The red pigment is no longer used in painting because of its poor light fastness.

Indian lac was another red pigment of organic origin obtained from a female insect (Coccus lacca), native to India.16 The female lac insects spend their entire lives clustered together in large groups on trees, and when the lac was harvested sticks were simply cut down from the trees with the insects still attached. Stick lac appears more like some type of growth on the tree than a group of living insects and this led to some confusion over the origins of lac. After harvesting, the dead insects were stripped from the sticks, crushed and mixed with hot water to separate the colouring matter. The water was evaporated, leaving the red pigment, which could be formed into cakes ready for use by painters.83 Indian lac is crimson in colour and quite transparent, but is rarely used in painting today. The lac insect is, however, still widely used today to provide shellac, a resin component in lacquers and varnishes.30

Brazil is a pigment produced from the wood of the Caesalpinia tree (Caesalpinia sappan), found in the East Indies and South America. It is a red pink colour and is obtained by reducing the brazil wood to a coarse powder and then boiling it in a mixture of water and vinegar. Alum is added to the mixture to precipitate the pigment, followed by gum arabic, to provide a binder. Brazil was a very popular pigment initially, but its usage declined during the seventeenth century because of its poor light fastness.82

The Netherlands

During the time of the Italian Renaissance there was a wide North/South divide in European art.2 The Italian masters were concentrating on clear perspective and the human figure while the Northern European painters were holding a mirror up to the world and trying to represent it realistically paying great attention to detail. This Northern style of art grew in the Netherlands.84 The artist Jan van Eyck (1390-1441) was a prominent figure in this movement.85 Van Eyck painted with great patience and attention to detail, developing new painting techniques to assist his style. At this time all painters prepared their own paints and often made their own pigments too, with the help of apprentices in the workshop. Painters were skilled in basic chemistry and science as well as the arts, and would often experiment with new ideas in much the same way a scientist would in the laboratory. Van Eyck found the medium of egg tempera to be too restrictive for his purposes so he began to experiment with new binders; he came across the idea of using oil as a binder, thus creating the oil paint.1,41,82 This new style of painting was quickly accepted by Van Eyck's contemporaries and gained popular acceptance throughout the artistic community in the North of Europe and eventually in Italy.86-88

Oil paints were made by grinding pigments in linseed oil to form a smooth, stiff paste, which could be applied to a canvas stretched across a wooden frame. The oil paints were versatile and slow drying, and could be applied in many layers with stiff brushes, palette knives or even the fingers. The paints could also be applied as opaque layers or in glossy transparent glazes to provide a wide range of visual effects.41

One of the palettes of Jan van Eyck from the early 15th century has been analyzed and found to contain eight pigments: brown earth, red madder, ultramarine, yellow ochre, green earth, orpiment, red ochre and peach stone black.89 Van Eyck created bright, colourful paintings and this serves to illustrate how skillfully he blended a limited number of basic pigments in his work.

The High Renaissance

In 15th century Italy, the mediums of egg tempera90 and fresco91 were still very much in favour, and artists, having tackled the problems of perspective, began to explore light and shadows and the composition of their paintings.2 Representing realistic figures in perspective against a background was difficult, but arranging these scenes harmoniously often proved impossible, and many early attempts were clumsy. The Florentine painter Sandro Botticelli (1444-1510) tackled these problems with great success.92-94 A beautiful example of this harmonious composition can be seen in his painting Birth of Venus.95

The turn of the 16th century saw the most famous era in Italian art begin.96,97 This was the High Renaissance, where perfection in art appeared to have been attained.98,99 The great artists Leonardo da Vinci (1452-1519)100-102, Michelangelo Buonarroti (1475-1564)103-105 and Raphael (1483-1520)106-108 were the most noted of this time; together they embody all the discoveries of the Renaissance. Some of the greatest works of art such as the Mona Lisa and the frescos of the Sistine Chapel were created during this time and have influenced our interpretation of religious events and painting styles ever since.91 Artists in this period also became famous in their own right and were elevated above their traditional status as craftsmen, much in the way they had been treated in the golden era of classical Greece.109,110 The achievements of the Renaissance could be summarized as the discovery of perspective, the use of colour and light to achieve harmony, and the attainment of perfection in art.111

While the High Renaissance occurred in Italy, the art of Northern Europe continued to develop along different lines until a technological innovation from Germany in the 15th century changed the way in which people communicated artistic ideas with one another. This development was wood block printing.112 Images were carved into blocks of wood, which were then coated with a basic printing ink of carbon black pigment in oil, to produce crude printed images.113 A short time later Johann Gutenberg (1397-1468)114,115 developed moveable wooden blocks that were the forerunner of the printing press. The invention of printing allowed drawing and illustrations to be reproduced for mass consumption.116 Enthusiasm for printed material subsequently led to the development of copper plate engraving, and many artists began to work in this medium rather than painting.117 A prominent artist of the 15th century who worked in copper engraving was the German Martin Schongauer (1453-1491).118,119 Knowledge of copper engraving soon spread throughout Europe and allowed artists to communicate new ideas and works. A great merger of art styles in Europe took place and caused a new era of wholly European art to begin.

After the Renaissance many people began to wonder where art could possibly go next since it was widely believed that no more could be achieved. Something of a crisis occurred in art that took several centuries to be resolved. Many painters (often called the Mannerists) experimented with new ideas and forms.120,121 Some deliberately disregarded the rules of harmony and perfection while others set out to shock the public with their new inventions. This sometimes led to surprisingly modern results and is well illustrated in the works of the Greek painter Domenikos Theotokopoules (1541-1614), known as El Greco.122,123 These paintings are exciting and show obvious disregard for natural forms and colours.124 Unfortunately many of the paintings of this era were not so distinguished as those of El Greco, and many of the artistic experiments carried out have simply been forgotten.

Northern Europe

In Northern Europe, particularly in Germany and the Netherlands, the lessons of the Renaissance were absorbed and blended with traditional Gothic styles to create something original. The German artist Albrecht Dürer (1471-1528)125 was typical of this era. He was one of the first landscape painters, an entirely new subject matter for artists of the day.126 His paintings showed the beauty of a natural landscape depicted in precise, attentive detail, with no specific subject matter or religious theme. Dürer was also one of the first artists to use watercolours in their modern sense.127

Watercolours are dried blocks of paint produced to be easily dispersible in water.41 The pigment was mixed in some type of binder, traditionally gum arabic, and then dispersed in water. The water was subsequently evaporated to give dry tablets of paint that could be readily redispersed and applied to the painting surface. Watercolour did not really gain widespread popularity until the eighteenth century but was often used in the Netherlands from the time of Dürer.82

The Reformation
A serious crisis of a different kind was faced by the painters of Northern Europe and was brought about by the religious reformation of Martin Luther128, which caused huge upheaval throughout many countries.129 This was the time of the Thirty Years War (1618-1648)130 in continental Europe and the Civil War in England (1642-1649).131 Spain, France and Italy supported the Catholic Church and the principles of absolute monarchy, while England, the Netherlands and Germany became Protestant. With the Protestants came a great decline in artwork because much of the religious painting was regarded as little more than idolatry.132 As the vast majority of commissions for artists came from the creation of altar pieces for churches and cathedrals, a large source of income for artists was suddenly cut off.

New Styles of Art
Two solutions to the problems of the Reformation were adopted. The first was to continue finding commissions to paint pictures acceptable to the Protestant church, such as portraits. Artists who adopted this route included Rubens (1577-1640)133,134 and his apprentice Anthony Van Dyke (1599-1641), who both painted vibrant living portraits that often defined moments of history during these hectic times.135 Van Dyke became court painter for Charles I in England and his works have set the standard for the portrait of the archetypal aristocratic nobleman.136

The second pathway open to the artists of these times was just to paint without a commission then to try and find a buyer afterwards.137 We accept this idea without compunction today, but at the time this was a complete turnaround in the way art was created. This development in some ways led to more freedom for the artist, but also led to the times of painters living in abject poverty when no one would buy their work. Competition in the painting market was very intense, and painters became more and more specialized in their work.138 The first still life paintings were created during the time of the Reformation.139,140 They used subject matter that would not offend the Protestant church but would also be attractive enough for a wealthy merchant to purchase for his home.

The undoubted master of this time was Rembrandt van Rjin (1606-1669)141, who came from an affluent family in the Netherlands and initially enjoyed great success. Gradually his popularity declined and he died in poverty, owning only some old clothes and painting equipment. Rembrandt painted realistic, faithful pictures that seemed to give some insight into the social events of his time.142 His paintings were dark and he was not attracted to paint beautiful things, yet there was intense beauty in his works. He is most famous for a set of frank self portraits, which spanned an entire lifetime.143

New Pigments
During the period from the Renaissance to the 17th century not many new technical discoveries in the field of pigments were made. Most artists' colours added to the palette were from natural sources and many of these were only used for short periods of time.

A few more widely used pigments were introduced in this time. These included Vandyke brown (also called cassel earth), which came to prominence in the early 1600s due to its popularity with the painter Van Dyke.16 It was a dark brown, transparent colour extracted from lignin or peat deposits, so was organic in nature and not a mineral earth.

Trade with India
Two yellow pigments of note were introduced to Europe from the East around 1600.144 European links with the Near and Far East were just beginning to expand145, and in England many new items were imported by the East India Company.146 The first of these pigments was gamboge16, an organic pigment made from the gum of the garcinia evergreen tree. The trees were tapped by making incisions in the bark to let the gum drip out; the gum was then heated and run into hollow bamboo tubes where it was left to set. The hardened gum was removed for sale as hard sticks in Europe. Gamboge was used as a watercolour pigment and was something of a novelty, being both a pigment and a binder combined into one.1,147

The second yellow pigment imported from the East was called Indian yellowl8, and was made in only one small region of India near Monghyr.148 The pigment was made by feeding cows solely on a diet of mango leaves, which caused their urine to become bright yellow. The urine was collected and heated in order to precipitate the yellow colorant, which was then separated and formed into lumps ready for sale. Indian yellow was used mainly in watercolours and was a bright, very light fast pigment. Its use only declined when the Indian government later banned its manufacture on the grounds of animal cruelty.149

Both of these yellow pigments were widely used by artists before they were replaced in this century by synthetic colorants that were more reliable.150

Industrial Pigments
From the beginning of the 16th century a variety of synthetically produced blue pigments based on copper were used by artists.16 These tended to be grouped under the names of blue verditer, which was commonly basic blue copper carbonate, or azure, which tended to be the name given to every other blue copper-based pigment.

Blue verditer was the manufactured version of the pigment that occurred naturally as azurite, although it could also be produced as a green pigment akin to the green colour in malachite. The method of synthesis for verditer was discovered accidentally, the pigment arising as an impurity in the separation of silver from copper.16 During the separation process, copper nitrate solution came into contact with chalk and formed a green substance. The process was little understood in the 16th and 17th centuries, and sometimes a blue pigment was made while other times it was green, and sometimes no colorant at all was seen. It was not until the French chemist Pelletier analyzed verditer in the 18th century that a reliable method of production was generated.151 Blue and green verditer were by-products of an industrial process and so were favourably cheap, but because of their tendency for colour change they were not always widely used by the famous artists.17 Both pigments were recommended for beginners or, as a last resort, when the more expensive blue and green pigments were beyond reach.

Smalt was obtained from grinding blue glass and had been used since Egyptian times, but very little was understood about the nature of the blue colour.16 The element responsible for the blue colour was cobalt, which had been known and mined in Saxony from the 14th century, although it was not actually isolated and identified until the 18th century.152 The element occurs associated with silver, arsenic and bismuth, and this combination made the mining operation dangerous, with a high fatality and injury rate among the miners. Consequently, the cobalt mines were rumoured to be inhabited by goblins called kobolds, who were blamed for causing all the mining accidents and arsenic poisoning. The name of the goblins was transferred to the metal ore and eventually to the metallic element itself. After being mined, the cobalt ore was heated strongly in a furnace to drive off the arsenic in a white smoke.153 The poisonous smoke was channeled off down long wooden tunnels out of harm's way, although the process could hardly be described as safe! The cobalt oxide produced was then used to make the marvellous dark violet blue glass characteristic of smalt. The ground glass was used as a pigment up until the 19th century, and was even used as an early brightener for white clothes by laundresses.l

Originally titled "A Colour Chemist's History of Western Art", published in Review of Progress in Coloration, Millennium Issue, Vol. 29, 1999, pp 43-64, Society of Dyers and Colourists, Bradford, UK.

1. Osborne, R. Lights and Pigments; London: John Murray, 1980.
2. Gombrich, E.H. The Story of Art; 15th Ed. London: Phaidon, 1995.
3. Leroi-Gourhan, A. The Dawn of European Art; Cambridge: CUP, 1982.
4. Larousse Encyclopaedia of Prehistoric and Ancient Art, 2nd Ed., Ed. Huyghe, R. London: Hamlyn, 1981.
5. Ruspoli, M. The Cave of Lascaux London: Thames and Hudson, 1987.
6. Brodrick, A.H. Lascaux: A Commentary; London: Lindsay Drummond, 1949.
7.Bataille, G. Prehistoric Painting; London: Macmillan, 1980.
8. Leroi-Gourhan, A. The Art of Prehistoric Man in Western Europe; London: Thames and Hudson, 1968.
9. Sieveking, A. The Cave Artists; London: Thames and Hudson, 1979.
10. Windels, F. The Lascaux Cave Paintings; London: Faber and Faber, 1949.
11. Laming, A. Lascaux: Paintings and Engravings; Harmondsworth: Penguin, 1959.
12. Parkyn, E.A. An Introduction to the Study of Prehistoric Art; London: Longmans, 1915.
13. Blum, A. A Short History of Art from Prehistoric Times to the Present Day for the Use of Students and General Readers; London: R.T. Batsford, 1926.
14. Sandars, N.K. Prehistoric Art in Europe, 2nd Ed.; Harmondsworth: Penguin, 1985.
15. Powell, T.G.E. Prehistoric Art; London: Thames and Hudson, 1966.
16. Harley, R.D. Artists' Pigments 1600-1835, 2nd Ed.; London: Butterworths, 1982.
17. Paint and Painting; London: Tate Gallery Publications, 1982.
18. Feller, R.L. Artists' Pigments; Cambridge: CUP, 1986.
19. Kenrick, J. Ancient Egypt Under the Pharaohs; London: B. Fellows, 1850.
20. Gardiner, A. Egypt of the Pharaohs; Oxford: OUP, 1961.
21. Davis, W. The Canonical Tradition in Ancient Egyptian Art; Cambridge: CUP, 1989.
22. Worringer, W. Egyptian Art; London: G.P. Putnam, 1928.
23. Aldred, C. Egyptian Art in the Days of the Pharaohs 3100-320 BC ;London: Thames and Hudson, 1980.
24. Smith, W.S. The Art and Architecture of Ancient Egypt; Harmondsworth: Penguin, 1958.
25. Stuart, V. The Funeral Tent of an Egyptian Queen; London: J. Murray, 1882.
26. Flinders Petrie, W.M. The Arts and Crafts of Ancient Egypt; Edinburgh: Foulis, 1909.
27. Encarta 97 (Microsoft 1997).
28. Weinstein, M. Precious and Semi-Precious Stones, 4th Ed.; London: I Pitman & Sons Ltd., 1944.
29. Webster, R. Gems: Their Sources, Descriptions and Identification, 2nd Ed.; London: Butterworths, 1972.
30. Innes, J. Trade Secrets: Classic and Contemporary, Surfaces and Finishes; London: Phoenix, 1995.
31. Levey, M. Chemistry and Chemical Technology in Ancient Mesopotamia; New York: Elsevier, 1959.
32. Saltzman, M.; Keay, A.M; and Christensen, J. Dyestuffs, 44 (1963) 241.
33. Abrahams, D.H.; and Edelstein, S.M. Amer. Dyestuff Rep., 55 (1964) 19.
34. Grierson, S. The Colour Cauldron; Perth: Grierson, 1989.
35. King James Bible, Isaiah 1:18, Exodus 26:1, Hebrews 9:19.
36. Selected Letters of the Younger Pliny, Ed.; E.T. Merrill London: Macmillan, 1903.
37. Pliny, C. Caecili: Secundi Epistilae et Panegyricus, Notis Illustrata; Oxonii e Theatro, 1686.
38. Wright, N.P. Amer. Dyestuff Rep., 52 (1963) 635.
39. Evans, A. Knossos Fresco Atlas; Farnborough: Gregg Press, 1967.
40. Church, A.H. The Chemistry of Paints and Painting, 4th Ed. London: Seeley, 1915.
41. Ayres, J. The Artists' Craft; London: Phaidon, 1985.
42. Mayer, R. A Dictionary of Art Terms and Techniques; London: A. and C. Black, 1969.
43. Hood, S. The Arts in Prehistoric Greece; Harmondsworth: Penguin, 1978.
44. Pollitt, J.J. The Art of Ancient Greece; Cambridge, CUP, 1990.
45. Carpenter, T.H. Art and Myth in Ancient Greece; London: Thames and Hudson, 1991.
46. Walters, H.B. History of Ancient Pottery; London: J Murray, 1905.
47. Pollitt, J.J. The Ancient View of Greek Art; New Haven: Yale University Press, 1974.
48. Imhoof Blumer, F.W. Ancient Coins Illustrating Lost Masterpieces of Greek Art; Chicago: Argonaut, 1964.
49. Ancient Greek Art and Iconography, Ed. W.G. Moon; Madison: University of Wisconsin Press, 1983.
50. Pollitt, J.J. Art in the Hellenistic Age; Cambridge: CUI; 1982.
51. Coulson, W.D.E. An Annotated Bibliography of Greek and Roman Art, Architecture and Archaeology; London: Garland, 1975.
52. Boardman, J. The Diffusion of Classical Art in Antiquity; Princeton: Princeton University Press, 1994.
53. Tompsett, D.H. Sepia; Liverpool: University Press of Liverpool, 1939.
54. Gasparini, L. Ink from an Octopus; Willowdale, Ontario: Hounslow Press, 1989.
55. Bentor, Y.K; and Naster, K. J. Sedimentary Petrol., 35 (1965) 155.
56. Buckley, H.A.; Bevan, J.C.; Brown, K.M.; Johnson, L.R; and Farmer, V.C. Min. Mag., 42 (1978) 373.
57. Isager, J. Pliny on Art and Society; London: Routledge, 1991.
58. E. J. Dunn in Treatise on Coatings, Vol. 3, Ed. R.R. Myers; New York: J.S. Long, 1975.
59. Pigment Handbook, Vol. 1, Ed. T.C. Patton; New York: John Wiley, 1973.
60. Brown, O.W.; and Nees, A.R. J. Ind. Eng. Chem., 4 (1912) 867.
61. The Elder Pliny's Chapters on Chemical Subjects, Part 1, Ed. K.C. Bailey; London: Arnold, 1929.
62. Gettens, R.J.; Feller, R.L.; and Chase, W.T. Studies in Conservation, 17 (1972) 45.
63. Woodford, S. The Art of Greece and Rome; Cambridge: CUP, 1982.
64. Burn, L. The British Museum Book of Greek and Roman Art; London: British Museum, 1991.
65. DeRose Evans, J. The Art of Persuasion; Ann Arbor: University of Michigan Press, 1992.
66. Lendon, J.E. Empire of Honour; Oxford: OUP, 1997.
67. Hubert, J.; Porcher, J.; and Volbach, W.F.; Europe in the Dark Ages; London: Thames and Hudson, 1969.
68. Duby, G. The Age of Cathedrals; London: Groom Helm, 1981.
69. Focillon, H. The Art of the West in the Middle Ages; London: Phaidon, 1963.
70. Betting, H. Likeness and Presence; Chicago: University of Chicago Press, 1994.
71. Ladner, G.B. Images and Ideas in the Middle Ages; Roma: Edizioni di Storia e Letteratura, 1983.
72. Evans, J. The Art of Mediaeval France 987-1498; Oxford: OUP 1948.
73. Cole, B. Giotto and Florentine Painting 1280-1375; New York: Harper and Row, 1976.
74. Baxandall, M. Giotto and the Orators; Oxford: Clarendon Press, 1971.
75. Welch, E.S. Art and Society in Italy 1350-1500; Oxford: 0UP, 1997.
76. Wölffin, H. Classic Art: An Introduction to the Italian Renaissance; London: Phaidon Press, 1953.
77. Gombrich, E.H. Norm and Form, 2nd Ed.; London: Phaidon, 1971.
78. Castelfranco, G. Donatello; Firenze: Martello, 1981.
79. Hart, F.; and Finn, D. Donatello; London: Thames and Hudson, 1974.
80. Cole, B. The Renaissance Artist at Work; London: John Murray, 1983.
81. Doerner, M. The Materials of the Artist and Their Use in Painting With Notes on the Techniques of the Old Masters (trans. E. Neuhaus); New York: Dover, 1962.
82. Birren, F. History of Colour in Painting; New York: Van Nostrand Reinhold, 1965.
83. Eastlake, C.L. Methods and Materials of Painting of the Great Schools and Masters, Vol. l; New York: Dover Publications, 1960.
84. Pächt, O. Van Eyck and the Founders of Early Netherlandish Painting; London: H. Miller, 1994.
85. Harbison, C. Jan van Eyck; London: Reaktion, 1991.
86. Wright, C. Paintings in Dutch Museums; London: Sotheby Park Bernet, 1980.
87. Seidel, L. Jan van Eyck's Arnolfini Portrait; Cambridge: CUP 1993.
88. Friedländer, M.J. Early Netherlandish Painting from van Eyck to Bruegel; London: Phaidon, 1956.
89. Hiler, H. The Techniques of Painting; Oxford: OUP, 1934.
90. Maxwell, A.; and Allen, G. A Manual of Tempera Painting; London: G. Allen and Unwin Ltd., 1930.
91. Millard, M. The Great Age of Fresco; London: Phaidon, 1970.
92. Chiesa, A. Botticelli and His Contemporaries; London: Batsford, 1960.
93. Lightbrown, R.W. Sandro Botticelli; London: Thames and Hudson, 1989.
94. Lightbrown, R.W. Sandro Botticclli; London: Elek, 1978.
95. de Angelis, R. Botticelli; London: Granada, 1980.
96. Wackernagel, M. The World of the Florentine Renaissance Artists; Princeton: Princeton University Press, 1981.
97. Welch, E.S. Art and Authority in Renaissance Milan; New Haven: Yale University Press, 1995.
98. Gilbert, C.E. Italian Art 1400-1500; London: Prentice Hall, 1980.
99. Klein, R.; and Zerner, H. Italian Art 1500-1600; London: Prentice Hall, 1966.
100. Clark, K. Leonardo da Vinci; Harmondsworth: Penguin, 1989.
101. Kemp, M. Leonardo da Vinci; London: Dent, 1981.
102. Mathe, J. Leonardo da Vinci, Anatomical Drawings 1452-1519; London: Liber, 1984.
103. Hibbard, H. Michelangelo, 2nd Ed.; New York: Harper and Row, 1974.
104. Berti, L. All the Works of Michelangelo; Firenze: Bonechi Editore, 1968.
105. Bull, G. Michelangelo; Harmondsworth: Penguin, 1996.
106. Cocke, R; and de Vecchi, P. The Complete Paintings of Raphael; London: Widenfeld and Nicholson, 1969.
107. Ettlinger, L.D.; and Ettlinger, H.S; Raphael; London: Phaidon, 1987.
108. Jones, R.; and Penny, N. Raphael; New Haven: Yale University Press, 1983.
109. Kempers, B. Painting, Power and Patronage; Harmondsworth: Penguin, 1994.
110. Stephens, J.N. The Italian Renaissance; London: Longman, 1990.
111. Barasch, M. Light and Colour in the Italian Renaissance; New York: New York University Press, 1978.
112. Berry, W.T.; and Poole, H.E. Annals of Printing; London: Blandford, 1966.
113.Morrison, S.; and Jackson, H. A Brief Survey of Printing; London: Fleuron, 1923.
114. McLuhan, M. The Gutenberg Galaxy; Toronto: University of Toronto Press, 1962.
115. Kapr, A. Johann Gutenberg (trans. D. Martin); Aldershot: Scholar Press, 1996.
116. Febvre, L. The Coming of the Book; London: NBL, 1976.
117. Lewis, J. Anatomy of printing (London: Faber, 1970).
118. Schongauer, M. The Complete Engravings of Martin Schongauer, Ed. A. Shestack; London: Dover Publications, 1969.
119. Minott, C.I. Martin Schongauer; New York: Collectors Editions, 1971.
120. Murray, L. The Late Renaissance and Mannerism; London: Thames and Hudson, 1967.
121. Hauser, A. Mannerism (trans. E. Mosbacher); London: Routledge and Paul, 1965.
122. Davies, D. El Greco; London: Phaidon, 1976.
123. El Greco: Italy and Spain, Ed. J. Brown and J.M.P. Andrade; Hanover: National Gallery of Art, 1984.
124. El Greco: Mystery and Illumination; Edinburgh: National Gallery of Scotland, 1989.
125. Hutchinson, J.C. Albrecht Dürer; Princeton: Princeton University Press, 1990.
126. Panofsky, E. The Life and Art of Albrecht Dürer, 4th Ed.; Princeton: Princeton University Press, 1971.
127. Wölffin, H. The Art of Albrecht Dürer (trans. A. Grieve and H. Grieve); London: Phaidon, 1971.
128. Atkinson, J. Martin Luther and the Birth of Protestantism; Harmondsworth: Penguin, 1968.
129. Brecht, M. Martin Luther; Philadelphia: Fortress, 1985.
130. Parker, G. The Thirty Years War; London: Routledge and Kegan Paul, 1984.
131. The English Civil War, Ed. R. Cust and A. Hughes; London: Arnold, 1997.
132. Coulton, G.G. The Art of the Reformation; Oxford: Blaxwell, 1928.
133. White, C. Peter Paul Rubens; New Haven: Yale University Press, 1987.
134. Van der Meulen, M. Rubens; London: Harvey Miller, 1994.
135. Dynasties: Painting in Tudor and Jacobean England 1530-1630, Ed. K. Hearn; London: Tate Gallery, 1995.
136. The British Portrait 1660-1960; Woodbridge: Antique Collector's Club, 1991.
137. Christensen, C. Art and the Reformation in Germany; Athens: Ohio University Press, 1979.
138. Lewis, F. A Dictionary of Dutch and Flemish Flower, Fruit and Still Life Painters; Leigh-on-Sea: F. Lewis, 1973.
139. Sterling, C. Still Life Painting, 2nd Ed.; New York: Harper and Row, 1981.
140. Grimm, C. Still Life; Stuttgart: Belser, 1990.
141. White, C. Rembrandt; London: Thames and Hudson, 1984.
142. Haak, B. Rembrandt Drawings; London: Thames and Hudson, 1976.
143. Nash, J.M. The Age of Rembrandt and Vermeer; London: Phaidon, 1972.
144. Watt, G. A Dictionary of the Economic Products of India, Vol, 6; London: John Murray, 1892.
145. Lawson, P. The East India Company; London: Longman, 1993.
146. Philips, C.H. The East India Company 1784-1834; Manchester: Manchester University Press, 1961.
147. Chandra, M. The Technique of Mughal Painting; London: Lucklow, 1949.
148. Mukharji, T.N. J. Soc. Arts, 32 (1884) 76.
149. Baer, N.S.; Indictor, N.; and Joel, A. Proc. Congress of Int. Inst. for Conservation (1972) 401.
150. Field, G. Chromatography; London: G Field, 1835.
151. Partington, J.R. A History of Chemistry; London: Macmillan, 1964.
152. Halse, E. Cobalt Ores; London: J. Murray, 1924.
153. Cobalt; Brussels: Centre d'Information du Cobalt, 1960.