Pigments used by the Early Painters of the Italian, Flemish and other European Schools.
THE pigments used by the ancients were mostly derived from native earths and minerals, and were very few in number. Mention has been made in regard to these in the early chapters of this work, when treating of ancient polychromy and painting. Besides the native earth pigments the ancients used a few other colours that were artificially made. This we know on the authority. of Pliny and Vitruvius, who wrote on the subject of the arts in the first century. Before we describe the more important pigments that were used by the painters of the Italian, Flemish, and other schools, it will be necessary to give a short description of those that were used by the ancients, for it must be understood that the same, or very similar pigments, were used by all artists from the earliest historic periods, and that they were merely augmented in number in the course of time ; some of them are still in use at the present day that were also employed by the Egyptians two thousand years, at least, before the beginning of the Christian era.
WHITE pigments were obtained from lime, gypsum, whiting or chalk, and white lead ; the latter was the native cerusite, a carbonate of lead which was in use as early as 400 B.C. Oxides of tin and zinc were also used as white pigments from a very early date.
YELLOW pigments were chiefly native earths such as the ochres and siennas.
BLUES.The finest blue known to the ancients, or in modern times, was that obtained from the lapis lazuli, a costly mineral which afforded most beautiful varieties of light and dark hues of the colour known as Ultramarine.
The finest quality of the modern artificial ultramarine blue is somewhat similar in colour to the natural variety, and has the same chemical constituents, and, excepting that it is harsher in hue, it is little inferior in other respects to the lazulite blue.
Indigo blue, or a colour very similar to it, was used by the Egyptians, more particularly as a dark blue dye. This colour seems to have been derived from a kind of fish, and not from the indigo plant. It is the purpurissium indicum mentioned by Pliny, and was known to the Italian writer, Cennini, as indaco baccadeo. It had little or no claim, however, to permanency.
Some other bright mineral blues used by the ancients were those obtained by compositions of copper, sand, and carbonate of soda, which have proved fairly permanent.
REDS.As regards red pigments, many shades of this colour were obtained from the native red oxides of iron, varying from an orange to a purple hue. Besides these the ancients used burnt ochres and siennas to obtain reds, as we do today, and we find them perfectly permanent.
The term ” sinopia,” and its different renderings such as ” sinopis,” ” cynople,” ” sinopre,” ” cinobrium,” etc., have been applied to different red pigments, over and over again, in classical and mediæval documents, to colours which embrace red iron earths, minium, or red lead, madder-red and vermilion, or the native red cinnabar. The latter word is derived from sinopia, and therefore the true sinopia would simply be cinnabar or native quicksilver vermilion, the native red sulphide of mercury. The sinopia mentioned by Pliny as having been used by Apelles was a native oxide of iron brought from Sinopia, a city of Pontus, also from Egypt and the Balearic Isles. This was probably hematite, the mineral from which is obtained the modern pigment known as Indian red, and not the brilliant red derived from cinnabar earth. It is somewhat surprising to read in the MSS. of Alcherius (circa 1400), that ” sinopis is a colour redder than vermilion ; it is also called cinobrium and mellana, and is made from madder.” Cinnabar or vermilion is one of the oldest colours known to the Chinese, as they used both the native and artificial varieties more than two thousand years ago, and Chinese vermilion was imported from China into Europe in the thirteenth century. The native cinnabar was, however, prepared as a pigment and used by artists in Europe at a much earlier date. It is obtained from the quicksilver mines of Europe, and notably from those of Spain, where it is still found.
From the mass of evidence which has been furnished by the old Roman, Italian, and Spanish writers on artists’ pigments we are enabled to come to the conclusion the term ” sinopia ” from Pliny’s time until the fifteenth century was applied to almost any ” red earth ” that furnished a bright red colour, but that the term was no longer applied to such red earths after this date, but used more particularly to define the most important and brightest of all red earths, namely, cinnabar, or native quicksilver vermilion.
GREENS.The chief greens used by the ancients were obtained from powdered malachite and from terre verte, a green earthy ochre, also the Grecian green, a kind of verdigris, but some other greens, composed of copper blues mixed with yellow earths, were also used.
Browns were native earths, such as the reddish brown ochres and bituminous earths. Umbers were not in use until the sixteenth century. Blacks were obtained from burnt or charred bones, burnt ivory, charcoal and soot, known as lampblack.
All the pigments mentioned above were not only used by artists from the earliest times to the end of the sixteenth century, but all of them, though in some cases they are under different names, are in use at the present day.
At the present time, however, there are upwards of two hundred colours, many of which are mixtures of two pigments, that are prepared and sold by artists’ colourmen, but only about twenty or less of them are reliable pigments.
Description of the Chief Pigments used by the Early Italian, German and Flemish Painters.
WHITE.-Bianco sangiovanni ; biacca ; gypsum ; chalk; zinc and tin oxides. According to Cennini, as stated in his Treatise on Painting, 1437, bianco sangiovanni was made from lime, for use in buon fresco painting. His method of its preparation was to pulverize white slaked lime, which was then mixed with water and stirred frequently during the space of eight days ; most of the water was then drawn off, and the remaining lime paste, or putty, was made into small cakes and dried in the sun. These cakes when thoroughly dried, he recommends, should be ground very finely in water, this paste being dried again, and ground a second time, in order to improve the white tint.
In the more modern Italian methods the lime-white pigment used in fresco painting is not dried into cakes and ground in water, but is used in its first wet state, after being strained through a fine muslin cloth in order to remove grittiness and impurities. Biacca is a white lead pigment. Cennini says that this pigment ” is proper for pictures, and is sometimes used on walls ” (by ” walls ” the Italian writers always meant fresco), but, he adds the warning, if it should be used in fresco, to ” beware of it nevertheless, for in time it becomes black.” It is doubtful if it was so used to any extent in fresco painting at any time.
Preparations of chalk and gypsum were used in gesso grounds for painting on panels and on canvas. Zinc and tin oxides were used as white pigments in miniature and in pottery painting.
REDS.–Sinopia ; cinabrese ; cinnabar (vermilion) ; amatisto or amatito ; minium ; lake ; dragon’s blood ; terra rossa d’Inghilterra.
The term “sinopia ” which has been given to various red pigments has previously been considered on pages 181-2. Cennini has little to say about it, except that he gives it the alternative name of ” porphyry,” and remarks that it is ” a natural red pigment, good for painting either on pictures or on walls, in fresco or in secco.” He mentions “cinabrese” as a red pigment, consisting of the finest and lightest variety of sinopia, that a perfect flesh-red colour is made from a mixture of light cinabrese and bianco sangiovanni, and that this colour is not only good for ” faces, hands, and naked figures on walls ” (fresco), but that ” you may make with it beautiful draperies, which on walls look like cinnabar ” (vermilion). From this it is perfectly clear that the sinopia and cinabrese known to Cennini must have simply been fine varieties of a native form of hematite, a red oxide of iron, probably similar, if not the same substance as that which is now known as Indian or Persian red, as the quality and properties of the finest and purest Indian red, and its beautiful tints when mixed with lime-white, which have the appearance of delicate lake tints, are exactly such as he describes when sinopia and cinabrese are mixed with bianco sangiovanni (lime-white). Indian red in its purest and unadulterated form is pre-eminently the best of all reds, and is the most permanent that can be used in fresco painting. When used in oil or in water-colour painting its density and inclination to purple cause it to appear heavy-looking and opaque, but in fresco, when used in tints with lime-white, it becomes almost transparent, and is capable of furnishing a fine series of rosy tints.
The rich and deep Pompeian red, used by the Greco-Roman decorators, on the interior walls at Pompeii and Herculaneum, more than likely was composed of a mixture of a red, corresponding to the modern Indian red, and a madder lake, and to prevent the dense or heavy appearance of such a mixture it was spread over a ground of luminous white stucco, when the painting was executed ” a secco,” so that the white ground would help to impart a lasting transparency and brilliancy to the superimposed colour. When a red ground was required on the wet plaster, as in fresco, a little lime-white would be added to the red mixture to reduce its heaviness, and improve the brilliancy of the colour.
Tuscan red is a name that is given to a mixture of Indian red and madder lake.
CINNABAR, or quicksilver vermilion, was found in a native state, and also made artificially by the friars and apothecaries in Italy, in the fourteenth century. Artificial vermilion is the red sulphuret of mercury, that is, a compound of mercury and sulphur in the proportion of about one hundred parts of mercury to sixteen of sulphur, to which some potash lye is added in the manufacture. The word ” vermilion ” is derived from ” vermiculus,” signifying a little worm, the term being originally, as the French ” vermeil,” applied to the crimson lake pigments made from the ” coccus ilicis ” and the ” coccus cacti,” or cochineal insects, and often to almost any colour of a ruddy or rosy hue. These insects were called ” kermes ” by the Arabs. An infusion of the female insects precipitated on alum furnished the pigment kermesino, or cremesino, from whence is derived the word crimson. Vermilion though a fairly reliable colour has a tendency to turn brown or purplish in fresco, and even in oil, unless it is glazed with madder, or if used alone in oil-painting it should be with a varnish medium. When used in fresco it should not be applied directly on the lime plaster, but should be laid over a ground colour of Indian red, or red ochre, venetian red or light red for example. By washing, however, the vermilion pigment two or three times in lime water, previous to using it in fresco painting, it will be rendered much more likely to keep its colour, as this treatment causes the pigment to be rapidly impregnated with the lime, without injuring its brilliancy, and thus being saturated with lime it can be used with safety on the wet lime plaster of the fresco.
AMATITO, Or AMATISTO, was the name given by the old writers on painting to a red pigment that was prepared from an exceedingly hard stone, varying in colour from a bright rosy tint to a purplish one, and this has been claimed as the mineral colour which very nearly approached lake in its hue. Some writers have called it mineral cinnabar, but this is a mistake, as the best evidences go to prove that it was a native red hematite, a kind of iron-stone, very hard and fibrous or striated in composition. It was so hard that it had to be pounded in a bronze mortar before grinding it on a porphyry slab.
The derivation of amatito, like hematite, is from the Greek haima, signifying blood. There are two kinds of the amatito mineral, the hard and the soft varieties. The hard kind was employed not only as a colour in painting, but it was cut and polished into certain shapes and used as tools for burnishing gold. The softer kind was known under the name of ” matita rossa,” which is, literally, a red pencil, or the red crayon, that which was used so much for drawing by the Italian artists. Cennini remarks that the pigment amatito ” is proper for walls and fresco; and it makes a good colour such as cardinals wear, or a purple, or a lake colour.” It was evidently the colour used in fresco by Giotto and his school, as the nearest one approaching a lake that could then be used in fresco painting, but seems to have not been used after the beginning of the seventeenth century, probably on account of the difficulty of the grinding and preparation of the hard material, and also because that the purplish red hematite, Indian red, was found to be more easily ground and prepared, so the latter pigment eventually took the place that was hitherto given to the amatito colour.
Two varieties of this colour were used formerly by the Spanish painters, the more brilliant of which was known by the name of Albin, and the other, which was in some degree lower in tone, was called Pabonazo.
MINIUM, or RED LEAD, called cerusta usta by the ancients, was sometimes used by the old painters on pictures, and in miniature painting, but not on walls. It was not recommended, how-ever, on account of its objectionable qualities of changing to brown or black in the course of time. When used alone, and not in a mixture with other pigments, and especially when locked up in a varnish medium, it has been known to last a very long time.
LAKES.One variety of lake, of a crimson hue, called gomma lacca, or gum-lac, was a kind of red resin, or resinous secretion of a kind of cochineal insect deposited on twigs of plants. A solution of this resinous substance is precipitated on a solution of alum to make the pigment, which is also known as Indian lake. It was imported from the East, and used as a pigment by the Venetians and early Italian painters, but like the lakes derived from the cochineal and kermes insects, it was not permanent, and all of these pigments were superseded later by the more superior and more permanent madder lakes obtained from the root of the Rubia tinctorum, or madder plant.
MADDER LAKE was made in perfection in the Netherlands, and was exported to Venice and other places in Italy, as well as to Spain, Germany, and England. In the first half of the sixteenth century the madder plant was cultivated largely in Zealand ; Holland had then the monopoly of the sale of this colour.
In painting, madder lake has generally been used as a glazing colour on account of its great transparency of body. Titian used madder in this capacity over his vermilion tints in draperies, and Rubens, Frans Hals, and others used it as a glazing colour in their flesh painting. When used in glazes, or alone, madder lakes, such as rose madder and madder carmine, are reliable and permanent pigments, but they should not be used in mixtures with white lead or chrome yellows, for such metallic pigments destroy them.
All the cochineal lakes such as crimson lake, carmine lake, etc., are extremely fugitive colours whether used alone or in mixture with others, and should not be employed in picture painting. Another very fugitive red colour known as dragon’s blood was prepared from the resinous exudation of the tree called Pterocarpus draco, which was sometimes used as a glazing pigment when mixed with varnish, but it is easily destroyed when mixed with leads or chromates.
TERRA ROSSA D’INGHILTERRA, or Bruno d’Inghilterra, used by the old painters, is the pigment known as Venetian red, or English red. It is an iron ochre of a brick-red colour and is a useful and permanent pigment in oil, water colour, and in fresco. Like all iron ochres it darkens slightly in time, and should not be used with lake colours. The artificial and common Venetian red is a mixture of gypsum and oxide of iron. It is also made by calcining sulphate of iron, or copperas.
LIGHT RED is a useful and permanent pigment, and is prepared by calcining yellow ochre.
YELLOWS.The most useful and most important of the yellow pigments known to the ancients, and to artists of all periods until, and including, our own times, were those obtained from ochre earths, such as yellow ochre, Roman ochre, raw sienna, etc., all of which owe their colouring matter to the iron they contain. They are unctuous in their nature and can be depended on as being permanent in any medium.
MASSICOT is a light yellow lead pigment that was used by the Italian and Flemish painters, though it was condemned for its liability to darken when used with lead white, or with almost any other colour. It is really the same thing as minium, or red lead, with a lesser degree of oxidation.
NAPLES YELLOW is the giallorino of the Italians. It is an artificial pigment, formerly consisting of a compound of lead oxide and antimony, but now composed of zinc and antimony, which makes a more permanent colour. Much of the so-called Naples yellow is, however, now made from zinc or lead white and a little cadmium and ochre, or other yellow, added in varying proportions in order to obtain the pale, medium, or deep varieties of the imitation colour.
ORPIMENT (auripigmentum of the ancients), or king’s yellow, is a colour of a fine golden hue, and consists of a combination of the sulphide and oxide of arsenic. It is, therefore, highly poisonous. At one time it was a favourite colour on account of its brilliant hue, but in mixtures with other colours it has proved thoroughly unreliable, as it turns black when mixed with white lead, with ochres that contain iron, and with the chromates, as all colours do that contain arsenic or sulphates. If used at all, it should be alone ; and not mixed with or even laid under any other colour, as it destroys any colour that is glazed or superimposed on itself. It can, however, be used over any colour, except verdigris, without injury to itself, and therefore it was valuable as a finishing colour in the high lights of draperies, in which positions it was used by some of the old Flemish painters, and by heraldic painters also, where it could be safely used in a flat tint to represent gold. Miniatute painters have also used it in lieu of gold grounds. Cennini strongly condemns this pigment, but he admits that it is ” proper for heraldic painting,” that is, that it should be used alone, either as a finishing colour, or in flat tints, as in backgrounds of miniature painting. Risalgallo, or realgar, is red orpiment ; it is a native ore in which arsenic and sulphur are combined. It is of a bright orange-red hue, and is chiefly found in the fissures of the craters in volcanic and primitive mountains. It can also be made artificially. This pigment has all the faults of the yellow orpiment, and can only be safely used under the same conditions as the latter colour.
The old painters seem to have been fascinated by the beautiful golden yellow hue of orpiment, as being ” the finest yellow that is to be found.” Eastlake quotes De Mayerne, the Swiss physician to James I and Charles I of England, and author of the MSS. dealing with the chemistry of colours, that Vandyck, who was known to the writer, made use of orpiment, and he goes on to say : ” In making use of it, it should be applied by itself ; the drapery (for which alone it is fit) having been prepared with other yellows. Upon these when dry, the lights should be painted with orpiment : your work will then be in the highest degree beautiful.”
The damaged and faded appearance of some of Sir Joshua Reynolds’s portraits are due to the use of such colours as orpiment, carmine lake, and asphaltum, and particularly to the mixture of the former two pigments with white lead. Northcote in his Life of Reynolds says that at a certain period, about 1755, ” Carmine, orpiment, and blue black were at this time the representatives of red, yellow, and blue on Sir Joshua’s palette.” These immixtures of carmine and of orpiment with white lead would certainly be disastrous. In his late years Reynolds used also the treacherous asphaltum, and even mixed it with other colours, as well as using it as a glazing colour, with the result that it prevented the colours from drying, as it never really dries itself, except on the surface film, and when varnished afterwards the drying of the varnishes tore the underneath colours into numerous cracks, which has partially destroyed much of his fine painting.
GAMBOGE is a transparent bright yellow. It was used by the Dutch painters, and by the leather-workers as a glaze, or lacquer. It is a vegetal gum which exudes from various trees and is more useful and more permanent in water-colour than in oil. This pigment does not appear to have been known to Cennini. A certain yellow mentioned by him, under the name of Arzica, a chemical colour, which is now unknown, has been suggested as the pigment gamboge, but we have no positive proof of this, and besides a chemical colour could not be derived from a tree as gamboge is.
There were a great many varieties of yellow lakes used by the Dutch and Italian painters, all of which were chiefly obtained from the yellow, or greenish-yellow, colouring matter found in various berries, the inner barks of certain trees, and from flowers, such as the broom and saffron. The colouring matters derived from these vegetal sources were precipitated on solutions of alumina in order to obtain the required pigments, which went under such names as Dutch Pink, Brown Pink, Italian Pink, Quercitron Yellow, from the bark of a kind of oak tree, Madder Yellow, Saffron, Safferano, etc. None of these colours, however, could be called permanent, as they are all liable to change to reddish-orange, brown or grey tones, and when mixed with mineral or metallic colours they are completely destroyed. Many of the Dutch flower-paintings of the seventeenth and eighteenth centuries have now blue foliage which originally was green, but the yellows used in their mixtures with blue being vegetal lakes have now disappeared, leaving the blue to show where the yellow lakes have been used. It must be said, however, that when these yellowish lakes are used alone, as in glazing, or with an oleo-resinous vehicle, as in lacquers, they will last a long time, and keep their colour.
For example, Dutch Pink, which is a kind of olive or brownish green, is largely used in coach-painting, and has in this work always proved a sound and reliable colour, when it is locked up well in the varnish. The term ” pink,” connected with these yellow green pigments, simply means that they are manufactured in the same way as the red or pink lakes and madders.
BLUE.With the exception of the modern artificial ultramarine, and other varieties of the same pigment, there are scarcely any blue colours used to-day that were not known either to the ancients, or to the artists of every period from the end of the classical times up to the eighteenth century.
Foremost among the blues, in point of beauty, purity of hue, and permanency, is that pigment known as the genuine Ultramarine which is made from the native lapis lazuli, a precious stone found in Siberia and in other places in the East. It is the azzuro oltre marino of Cennini, who describes it as ” a colour more noble, beautiful, and perfect than any other colour ; and its good qualities exceed anything we can say in its favour.” The great cost of the native material and the difficulty of its preparation have prevented the extensive use of Ultramarine even in Cennini’s time, for with the exception of its employment in miniature painting, and in some instances for the painting of the blue drapery of the Virgin in pictures, and occasionally in fresco, this fine colour had a limited use. As regards its use in fresco painting, it was not often applied direct to the wet plaster, but in most cases it was used as in secco, or in egg-size distemper over a ground of a red colour, and for this reason it has generally fallen off nearly all of the old frescoes, and has left the red ground visible, which was first painted on the wet plaster as a preparation for the blue. In some of the panel pictures of the Italian, Dutch, and Flemish artists this colour is usually found to have been laid on very thinly ; this might have been so for two reasonsone, that the pigment was too costly to permit of it being laid on thickly, and another, that the purity of its tint permitted the bearing out of the full strength of its colour in spite of its thin application.
The constituent parts of lapis lazuli are alumina, silica, soda, and sulphur. The native stone has generally some particles of gold em-bedded in its structure. The Ultramarine pigment is prepared from the lazulite mineral by pounding it in a mortar to a fine powder, and by subjecting it to a prolonged and thorough grinding in water. When most of the azure tint is extracted by washing the well-ground colour, there remains a certain quantity of the grey bed rock or earth which is found with the lapis lazuli, and this residue of the powdered material with some of the extracted blue is ground to form the pigment known as Ultramarine Ash, which is a pale grey blue, and quite as permanent as the genuine Ultramarine, though very weak in colour. The lazulite Ultramarine approaches the nearest in hue of any colour to the spectrum blue, though it inclines rather to violet than to green; it is therefore the best of all blues to use in a mixture with madder lake, in order to obtain a deep and pure purple.
The artificial, or Factitious Ultramarine, known also as Guimet’s blue and French ultramarine, is a modern pigment almost as permanent as the genuine blue, and is of the same chemical constitution. It is a little harsher in tint than the native variety and inclines a little more to violet, but sometimes to a cobalt blue, the tint slightly varying with the methods of its manufacture.
If well made, it can be used as a good substitute for the lazulite blue, but if badly made, or when it contains too much free sulphur, it will blacken white lead ; even any variety of ultramarine, whether native or artificial, should not be used with leads or chromates. The best and most permanent variety of artificial ultramarine is that which is the deepest and most intense in hue.
AZZURRO DELLA MAGNA (d’Allemagne), or German blue, but more often called Azzurro,” was much used by the German, Flemish, and Italian artists. It was obtained from a blue copper ore, or carbonate of copper, and probably was similar in composition to the copper blues used by the ancients, and was a perfectly durable and trustworthy pigment in oil or tempera mediums. It was used on walls very much by the Italian frescanti ; not on the wet plaster, but in tempera with glue, or an egg-size medium, after the plaster on the walls had thoroughly dried. The blue draperies, and other places in the frescoes where this colour was required, were generally left to be painted finally in tempera. This accounts, as we have mentioned before, for the present bad state of whatever portion of the Italian frescoes, from and including the period of Giotto to Raffaelle, that were painted blue, for almost all of the blue portions, that were always painted in tempera, have disappeared, and if there are any exceptions, we may be pretty certain that such portions have been repainted in blue by restorers. It may be interesting, as bearing on this subject, to give the following extracts as quoted by Mrs. Merrifield in her book on Fresco Painting, 1846. The extracts are from letters written by Benozzo Gozzoli to Pietro de Medici, and preserved in the archives of the family of the Medici. He is speaking of the fresco of the Three Magi, in the Chapel of the Medici, in the Riccardi Palace at Florence : ” I should have come to speak to you, but I have begun this morning to put on the blue (Azzurro) and I cannot leave it. The heat is great, and the glue spoils directly. I think by next week I shall have completed this piece (Pontata). I think you would like to see it before I take down the scaffolding.” (Dated, Florence, July 10, 1459.) Again, ” I remind you to send to Venice for the blue (Azzurro), because by this day week, this side (Facciata) will be completed and I want the blue for the other.” Sept. 11, 1459) ” I had from the Jesuits two ounces of blue (Azzurro) of that kind which is three great florins per ounce.”
From these extracts we learn that Gozzoli followed the method of the other fresco painters in . Italy, in painting his blue draperies, etc., in secco, that is, in tempera on the wall, after the plaster had dried, and that he used glue size with his blue colours. The high price of Azzurro della Magna has led some modern writers to suppose that this pigment was COBALT blue, but although the native cobalt mineral was known in early times, the method of preparing it as a painter’s colour is comparatively modern. It is difficult to say when cobalt, as an artist’s pigment, was first used, but it is safe to state that it was not used to any great extent until about the beginning of the eighteenth century. Its invention must have been the result of tentative experiments in the extraction and preparation of the full-toned rich blue from the native cobalt ore, this being a natural development of the methods of obtaining the pigment known as smalt, or smalto, which is a much older pigment than cobalt blue, and is merely a glass, coloured with an oxide of cobalt. It is quite likely, however, that a still older form of smalt was composed of glass coloured with copper-blue. Both of these varieties of smalt are very weak in colour, but both of them are valuable and permanent in fresco or in enamel painting.
COBALT BLUE is composed of a silicate of cobalt and potassium, or it may be a nitrate, or sulphate of cobalt combined with white silicious sand and potash, or, a compound of cobalt and alumina. Sometimes it contains a little amount of nickel, the presence of which gives it a violet hue.
An old colour called Zaffre was a blue inclining to violet, made sometimes from a cobalt ore and ground glass, and also made from copper and glass. This was really a colour that may be described, as midway between cobalt blue and smalt. The latter pigment was generally prepared from zaffre. This colour was used by artists in Italy, and also by craftsmen as the colouring substance of blue glass objects. All forms of the pigments derived from cobalt are quite permanent when used in oil, water-colour, fresco, or enamel painting, and may be safely mixed with any colour.
It is conjectured, if not fairly evident, that the blue used in the frescoes and pictures of the Eclectic or Mannerist School of painters, in the seventeenth century, which include the works of the Carracci, Domenichino, Guido, and Guercino, was a cobalt blue. The blues used by these painters have stood remarkably well in comparison to those used by earlier artists in fresco painting, and although Domenichino painted his blue draperies in tempera on the dry wall, following the method of the older masters, on the other hand, Guercino put his blue to the severer test of painting it on the wet lime plaster, as for example, in his wall and ceiling pictures in the Sampieri Palace at Bologna, and in the garden-house of the former Villa Ludovisi in Rome, where the blue he used has stood remarkably well, having still kept its rich and soft colouring, so that we may be safe in saying that only a cobalt blue or the lazulite ultramarine could have been used in these works. The great cost of the latter colour would, however, prohibit its use on large fresco surfaces.
INDIGO BLUE was known to the Venetians and other Italians under a variety of names, such as indigo bago, indicum de bagadeo, indaco baccadeo and maccabeo. The two latter names are given to it by Cennini. It was known to Theophilus, in the twelfth century, as indigo bagadel or the indigo of Bagdad, from which place the best varieties were imported into Europe. The colour is extracted from the indigo plant which is cultivated in the East Indies and other countries. Indigo is extremely useful as a dye for fabrics, but as an artist’s pigment it is of little or no value, and should not be used, as the tint of this colour if required can be obtained by mixtures of other colours which are more permanent. When indigo is mixed with almost any other pigment it is soon destroyed, or completely changed; used alone in water colour washes, it keeps a fairly long time in pure air, but foul air changes it to a brownish hue. In oil colour when mixed with lead white or the chromates it is extremely fugitive. It cannot be used in fresco either, but as regards this, it is singular to find that Cennini recommends the use of indigo in mixture with lime-white for blue draperies in fresco painting, in one chapter of his treatise ; in another, he says indigo and lime-white is to be used for the under-painting of blue draperies, but goes on to say that ultramarine blue should be glazed over the indigo preparation colour.
GREENS : TERRE VERTE, Or VERDE TERRA was a favourite green pigment with the old masters. It is a natural grey-green ochre or earth of an unctuous nature, and owes its colour to the green hydrated oxide of iron which it contains. It is a good and permanent glazing colour. It darkens when used in oil, but owing to the silica and iron in its composition it is permanent when used in fresco. It should not be used with lake colours, as it destroys them, but may be mixed with other colours with safety. When calcined it makes a good brown pigment known as verona brown. Terre verte was used very much by the Italians as the first or ” dead colouring ” in flesh painting, and by gilders as a ground or preparation for gilding.
VERDACCIO was a compound green colour emplayed by the Florentine painters, and was called bazzeo by the Sienese. It consisted of a mixture of black and yellow ochre, and was used by the artists of both schools in the under-painting of flesh tints, in a semi-transparent manner on a white ground.
VERDIGRIS (” vert de Grèce “), or Verderame, was a bright green, much used as a glazing colour for draperies by the old painters. It is an acetate of copper, artificially made from copper and vinegar. The old form of verdigris dried so well that it had been a common practice to use it as a drier for dark colours and for slow-drying oils and varnishes. Eastlake states that the blackness of the shadows in the darker draperies in pictures of the Spanish Masters of the sixteenth and seventeenth centuries, and in those by Tintoret is quite likely due to the immoderate use of verdigris as a drier, for this pigment was commonly used as such in those days in Spain and in Italy.
Cennini, in his directions for making a ” beautiful green ornament ” mentions verdigris or verderame, advising that this pigment should be mixed with an oil vehicle and spread over bright tin. In Smith’s Antiquities of Westminster, 1837, it is related that a certain fragment of very old painted glass, inlaid as a panel in a compartment of a stone bracket that supported a statue in St. Stephen’s Chapel, had been painted on the under surface a very beautiful bright green, and this colour was proved to have been verdigris mixed with a varnish and applied to the under surface of the glass. On the back of this green coating a thin sheet of silver was hermetically fastened; the glass being thus treated was laid upon a cement that fastened it to the stone wall, and thus prevented any damp from coming through to the green colour. Although this green had been exposed to the daylight for hundreds of years, it was not affected by it, for the colour had still remained fresh and vivid, and the pigment being so well locked up in its varnish vehicle, and protected by the glass in front and the silver leaf behind, no air could get at it. This affords an interesting proof that even some doubtful and fugitive pigments if used alone, and locked up in any medium that would secure them from the effects of the atmosphere, may remain quite unchanged for almost any length of time.
It is well known that verdigris when mixed with, or used over or under, any colour but orpiment, almost destroys them, and must be used alone in a varnish. Artists, however, should avoid the use of this very undesirable pigment.
MALACHITE, also known as Mountain Green, is a hydrated carbonate of copper. It is found native, and also prepared artificially. The native malachite is a valuable green stone streaked with light veins. The green malachite pigment was known to the Egyptians. Like most copper greens it is affected by sulphur gases, but fairly permanent when used alone and protected from impure air, as in a varnish. It does not appear to have come under much notice, but this may be due, as some affirm, to the fact that verdigris has been confused with malachite by most early authorities on the subject of artists’ pigments.
VERDE AZZURRO.Cennini mentions this green, but does not describe it any further than by stating that it was made from the blue pigment azzurro della magna, so it may possibly have owed it green colour to an excess of the copper and zinc oxides with the blue from which it was derived.
Other greens were used by the old painters, but they were almost invariably compounds of certain blues and yellows.
BROWNS.In old documents the term ” brown ” has been applied to numerous colours embracing red ochres, dark reds, and even yellowish dark greens ; also to mixtures of red and black, blue and dull reds, etc. Purple-brown, formerly Spanish brown, is a modern name given to a dark variety of Indian red.
The most important browns are the umber earths, Vandyck brown, or Cassel earth, and a darker form of the latter known as Cologne earth. These browns were not known before the date of the sixteenth century and some of them later than this. All of them, including the Raw and Burnt umbers, are perfectly sound and reliable pigments. The umbers are good drying pigments, as they contain manganese, but the Vandyck browns dry badly owing to the bitumen in their composition.
RUBENS brown is a native ochreous earth, and is a lighter and warmer variety of Vandyck brown. It was a pigment very much used by Rubens and Teniers.
ASPHALTUM, or bitumen, is a brownish-black pitchy gum. It was known to the ancients, and was used as a glazing colour by the Flemish and Italian artists. The rich effect it gave to certain colours when first applied over them as a glaze was an inducement to artists to use it, but wherever it has been so employed it has proved disastrous to paintings, for it not only has a strong tendency to decompose in time into a sooty blackness, but as a rule it never dries thoroughly except on the surface, and the action of the surface-drying, when the underneath is still in a moist state, causes deep cracks in the work. Many old paintings show these disastrous effects caused by the use of asphaltum, and notably in some of the later pictures by Sir Joshua Reynolds, where he used this pigment in a lavish manner.
BLACK.Native black earths, or black chalks, such as Terra Nera di Roma or di Piedmonte and other kinds of black chalk were used by the old painters in fresco work. Carbonaceous blacks prepared from calcined bones, ivory, and charcoal are all useful and-permanent in oil or water colours, but they should not be, as a rule, used in fresco. There is one exception to this, however, that is ivory black, which is the most perfect of all carbonaceous blacks. Generally speaking it may be said that the ordinary black pigments in common use remain inert, and have little or no action on any pigments they may be mixed with.