The Metals and Pigments used in Illuminated Manuscripts[251].

The Metals and Pigments used in Illuminated Manuscripts^[251].

Fluid and leaf gold.

Fluid and leaf gold.Gold and silver or tin. The splendour of illuminated manuscripts of almost all classes, except manuscripts of the Irish school such as the Book of Kells, is largely due to the very skilful use of gold and silver. These metals were applied by the illuminator in two ways, first, as a fluid pigment, and secondly in the form of leaf.

The fluid method appears to have been the older. It is easier to apply, but is not comparable in splendour of effect to the highly burnished leaf gold, which was used with such perfection of skill by the illuminators of the fourteenth century.

Method of grinding.

Method of grinding.Fluid gold was made by laboriously grinding the pure metal on a porphyry slab into the finest possible powder. This powdered gold, mixed with water and a little size, was applied with a brush like any other pigment; see Theophilus, I. 30 to 33^[252]. When dry, it could be to some extent polished by burnishing, but as it was laid directly on to the comparatively uneven and yielding surface of the vellum it never received a very high polish. As a rule therefore fluid gold was left unburnished, and its surface remained dull or mat in appearance.

Dull and burnished gold.

Dull and burnished gold.For this reason it was not unfrequently used in conjunction with burnished leaf gold, a fine decorative effect being produced by the contrast of the mat and polished surfaces. Thus, for example, in fourteenth and fifteenth century manuscripts a delicate diaper of scroll pattern is sometimes painted with a fine brush over a ground of burnished gold leaf.

In the fifteenth century, during the decadence of the illuminator's art, the use of fluid gold, which had previously greatly diminished, was much revived, especially for the background of the realistic borders in Flemish manuscripts^[253], for touching in the high lights of miniatures, and for many other purposes. When used to cover large surfaces, it is always unsatisfactory in effect and has little decorative value.

Cistercian severity.

Cistercian severity.The preparation of this gold pigment was a very slow and laborious matter. The severe Cistercian rule regarded this process as a waste of precious time; and indeed the use of gold in any form was prohibited in the manuscripts used in Cistercian Abbeys. In the dialogue between a Cistercian and a Cluniac monk, De diversis utriusque ordinis observantiis (Thesaur. Nov. Anecdot. Vol. V. 1623), the Cistercian asks "what use there can be in grinding gold and painting large capitals with it"; aurum molere et cum illo molito magnas capitales pingere litteras, quid est nisi inutile et otiosum opus? St Bernard himself had an even stronger objection, not only to gold in manuscripts, but to any ornaments with grotesque dragons and monsters, on the ground that they did not tend to edification.

Fluid silver.

Fluid silver.Fluid silver was prepared and applied in the same way, but it was much less used than gold pigment. A very beautiful effect is produced in some of the gorgeous Carolingian manuscripts by using in the same ornament both gold and silver, which mutually enhance each other's effect by contrast of colour.

Leaf gold. Mordant ground.

Leaf gold.Burnished Gold leaf. The extraordinary splendour of effect produced by skilfully applied gold leaf depends mainly on the fact that it was laid, not directly on to the vellum, but on to a thick bed of a hard enamel-like substance, which gradually set (as it got dry) and formed a ground nearly as hard and smooth as glass; this enabled the gold leaf laid upon it to be burnished to the highest possible polish, till in fact the gold gave a reflexion like that of a mirror. This Mordant ground.enamel-like ground, or mordant as it was called, was commonly as thick as stout cardboard, and its edges were rounded off, which has the double result of making the gold leaf laid upon it look not like a thin leaf, but like a thick plate of gold^[254], and at the same time the rounded edges catch the light and so greatly increase the decorative splendour of the metal.

Convex surface.

Convex surface.Thus, for example, the little bosses and studs of gold, which are strewn so thickly among the foliage in the illuminated borders of Italian manuscripts of the fourteenth and fifteenth centuries, are convex in shape, like an old-fashioned watch-glass, and each boss reflects a brilliant speck of light whatever the direction may be in which the light falls upon the page. Perhaps the most sumptuous use of gold leaf is to be seen in some of the early fourteenth century French manuscripts, in which large miniatures are painted with an unbroken background of solid-looking burnished gold, with a mirror-like power of reflexion.

It was only by slow degrees that the illuminators reached the perfect technical skill of the fourteenth century in their application of gold leaf.

Purity of the gold.

Purity of the gold.In the first place the purest gold had to be beaten out, not the alloy of gold, silver and copper which now is used for making the gold leaf of what is called "the finest quality." The English illuminators at the close of the thirteenth and in the fourteenth century frequently got their gold in the form of the beautiful florins of Florence, Lucca^[255] or Pisa, which were struck of absolutely pure gold^[256]. In England there was no gold coinage till the series of nobles was begun by Edward III.^[257], but these were of quite pure gold, like the Italian florins, and so answered the purpose of the illuminator.

Another important point was that the gold leaf was not beaten to one twentieth part of the extreme tenuity of the modern leaf. The leaves were very small, about three by four inches at the most, and not more than from fifty to a hundred of these were made out of the gold ducat of Italy, which weighed nearly as much as a modern sovereign^[258].

In many cases, we find, the illuminator prepared his own gold leaf, and it was not uncommon for the crafts of the goldsmith and the illuminator to be practised by the same man. For example the Fitz-Othos, mentioned at page 112 as a distinguished Anglo-Norman family of artists in the thirteenth century, were skilful both as makers of gold shrines and as illuminators of manuscripts. Many interesting notes about the Fitz-Othos and other artists employed at Westminster during the thirteenth and fourteenth centuries are to be found among the royal accounts now preserved in the Record Office: see Vetusta Monumenta, Vol. VI., p. 1 seq.

Among the accounts of the expenses of decorating with painting the royal chapel of Saint Stephen at Westminster in Edward III.'s reign, we find that John Lightgrave paid for six hundred leaves of gold at the rate of five shillings the hundred, equal to about £5 or £6 in modern value. And John "Tynbeter" received six shillings for six dozen leaves of tin used instead of silver, not because it was cheap, but because tin was not so liable to tarnish.

These accounts are in Latin, which is not always of Ciceronian purity; a classical purist might perhaps carp at such phrases as these,

Item. Pro reparatione brushorum, viij^d, under the date 1307; and, in the following year,

Item. Unum scarletum blanketum, ij^s vij^d.

The scarlet blanket was not bought to keep the artist warm, but to make a red pigment from, as is described below at page 246.

Goldsmith artists.

Goldsmith artists.This close connection between the arts of the goldsmith and the illuminator had its parallel in other branches of the arts, and with results of very considerable importance. Many of the chief painters and sculptors of Italy, during the period of highest artistic development, were also skilful goldsmiths, as for example Ghiberti, Verrocchio, Ant. Pollaiuolo, Francesco Francia and many others.

This habit of manipulating the precious metals gave neatness and precision of touch to the painter, and in the art of illuminating manuscripts taught the artist to use his gold so as to produce the richest and most decorative effect.

The gold mordant.

The gold mordant.The mordant. We now come to the most difficult part of the illuminator's art, that of producing a ground for his gold leaf of the highest hardness and smoothness of surface. It is a subject dealt with at much length by all the chief writers on the technique of the illuminator, from Theophilus in the eleventh century, down to Cennino Cennini at the beginning of the fourteenth^[259].

Though differing in details, the general principle of the process is much the same in all; the finest possible sort of gesso, plaster, gypsum or whitening, was very finely ground to an impalpable powder, and then worked up with albumen or size to the consistency of cream, so that it could be applied with a brush. After the first coat was dry, a second and a third coat were added to bring up the mordant to the requisite thickness of body, so that it stood out in visible relief upon the surface of the vellum.

In order that the illuminator might see clearly where his brush was going, and keep his mordant accurately within the required outline, it was usual to add some colouring matter, such as bole Armeniac (red ochre), to the white gesso, which otherwise would not have shown out very clearly on the cream-white vellum. In many cases, however, this colouring matter is omitted.

Application of leaf.

Application of leaf.When the last coat of the gesso-mordant was dry and hard, its surface was carefully polished with the burnisher and it was then ready to receive the gold leaf; several days' waiting would often be required before the whole body of the mordant had set perfectly hard. White of egg was then lightly brushed over the whole of the raised mordant, and while the albumen was still moist and sticky, the illuminator gently slid on to it the piece of gold leaf, which he had previously cut approximately to the required shape. He then softly dabbed the gold leaf with a pad or bunch of wool, till it had completely adhered to the sticky mordant, working it with special care so as completely to cover the rounded edges. After the albumen was quite dry, and the gold leaf firmly fixed in its place, the artist brushed away with a stiff brush all the superfluous gold leaf; all the leaf, that is, under which there was no mordant-ground to hold it fast.

Burnishing process.

Burnishing process.The gold was then ready to be polished. For this purpose various forms of burnisher were used, the best being a hard highly polished rounded pencil of crystal or stone, such as haematite, agate, chalcedony and the like; or in lack of those, the highly enamelled tooth of a dog, cat, rat or other carnivorous animal was nearly as good^[260]. In fact patience and labour were the chief requisites; one receipt, in Jehan le Begue's manuscript, § 192^[261], directs the illuminator to burnish and to go on burnishing till the sweat runs down his forehead. But caution, as well as labour, was required; it was very easy to scratch holes in the gold leaf, so that the mordant showed through, unless great care was used in the rubbing. In that case the illuminator had to apply another piece of leaf to cover up the scratches, and do his burnishing over again. To secure the highest polish, illuminators burnished the hard mordant as described above before laying on the gold leaf. In most cases two layers of gold leaf were applied, and sometimes even more, in order to insure a perfect and unbroken surface.

Application of gold.

Application of gold.All writers speak of this burnishing as being a very difficult and uncertain process even to a skilled hand, requiring exactly the right temperature and amount of moisture in the air, or else it was liable to go wrong. If the gold was to be applied in minute or intricate patterns the illuminator did not attempt to cut his leaf to fit the mordant-ground, but laid it in little patches so as to cover a portion of the ornament. The superfluous gold between the lines of the pattern was then brushed away, as the leaf only remained where it was held by the mordant. With all possible care and skill, it was hardly possible always to ensure a sharp clean outline to each patch of gold; and so one commonly finds that the illuminator has added a black outline round the edge of each patch of gold, in order to conceal any little raggedness of the edge.

Receipts for the mordant.

Receipts for the mordant.As examples of mediaeval receipts for making the mordant I may mention the following:—

"Mix gypsum, white marble, and egg-shells finely powdered and coloured with red ochre or terra verde; to be mixed with white of egg and applied in thin coats, and to be burnished before the application of the gold." When dry, this mixture slowly set into a beautiful, hard and yet not brittle substance, capable of receiving a polish like that of marble, and forming the best possible ground to receive the gold leaf. Much of its excellence depended on the patience of the illuminator in applying it in very thin coats; each of which was allowed to dry completely before the next was laid on. When ready to receive the gold leaf, after the burnishing of the mordant was finished, some purified white of egg was brushed over to make the gold leaf adhere firmly so as not to work loose or tear under the friction of the burnisher.

Receipts for the mordant.

Receipts for the mordant.In some cases white lead (ceruse) was added to the gesso, as, for example, in a receipt, given by Cennino Cennini (§ 131 to 139, and 157,) for a mordant made of fine gypsum, ceruse and sugar of Candia, that is ordinary pure white sugar^[262]. This is to be ground up with white of egg, applied in thin coats and burnished. To colour the mordant Cennino adds bole Armeniac, or terra verde, or verdigris green.

Giovanni da Modena, a Bolognese illuminator, gives the following receipt for a different gold-mordant to be used with oil instead of albumen or size^[263]. Instead of gesso it is to be made of a mixture of white and red lead, red ochre, bole Armeniac and verdigris; the whole is to be ground first with water, then thoroughly dried, and again ground up with a mixture of linseed oil and amber or mastic varnish.

This variety of mordant appears to have been used in a good many fifteenth century Italian manuscripts. It is not such a good mixture as the gesso and white of egg, as the oil used to mix with it is liable to stain the vellum through to the other side of the page, and even to print off a mark on the opposite page, especially when the book has been severely pressed by the binder.

Tooled patterns. Stamped patterns.

Tooled patterns.Tooled patterns on gold leaf. In many Italian and French manuscripts, especially of the fourteenth and fifteenth centuries, a very rich and brilliant effect is produced with tooled lines impressed into the surface of the flat gold. Diapered and scroll-work backgrounds, the nimbi of Saints, the orphreys and apparels on vestments, and many other kinds of decoration were skilfully executed with a pointed bone or ivory tool, impressed upon the gold leaf after it was burnished, and through the gold into the slightly elastic body of the gesso-mordant. Stamped patterns.Patterns were also produced by the help of minute punches, which stamped dots or circles; these, when grouped together, formed little rosettes or powderings, like those used in the panel paintings of the same time. Gold treated in this way had to be of considerable thickness, and in some cases, when a large flat surface of mordant was to be gilt, as many as three layers of stout gold leaf were employed to give the requisite body of metal.

Silver leaf.

Silver leaf.Burnished silver leaf was occasionally used by the mediaeval illuminators, though not very often, as it was very liable to tarnish and blacken. For this reason leaf tin was not unfrequently used instead of silver, as tin does not oxydize in such a conspicuous way; see above, p. 233.

The use of all three metals, gold, silver and tin, is described by Theophilus, Schedula diversarum Artium, I. 24, 25 and 26. Theophilus speaks of laying the gold leaf directly on to the vellum with the help only of white of egg. This method was not uncommon in early times, and it was not till the end of the thirteenth century that the full splendour of effect was reached by the help of the thick, hard mordant-ground.

Cheap methods.

Cheap methods.Inferior processes were sometimes used for the cheap manuscripts of later times. Thus tin leaf burnished and then covered with a transparent yellow lacquer or varnish made from saffron was used instead of gold.

Cennino and other writers describe a curious method of applying gold easily and cheaply. The illuminator was first to paint his design with a mixture of size and pounded glass or crystal; this, when dry, left a surface like modern sandpaper or glass-paper, the artist was then to rub a bit of pure gold over the rough surface, which ground off and held a sufficient amount of gold to produce the effect of gilding. Only a very coarse effect, worthy of the nineteenth century, could have been produced by this process.