It will therefore be readily conceived that the artist in fresco has to encounter difficulties of no ordinary kind; a few of them are thus noticed by a writer in Rees’s Cyclopædia:—“From the necessity there is in the progress of this style of art, that it should be executed with rapidity, and from the impossibility of retouching it without injuring the purity of the work, the artist, unless he be endowed with very extraordinary powers of imagination and execution indeed, is obliged to prepare a finished sketch of the subject, wrought to its proper hue and tone of colour, and so well digested, that there may be no necessity for making any essential alterations in the design. This, which is a very useful mode of proceeding in all fine works of painting, is absolutely indispensable in fresco, to those who are not determined to give the rein to their ideas, and leave as perfect whatever may first present itself. There is no beginning in this, by drawing in the whole of the parts at one time, and correcting them at leisure, as is the custom with oil-painters, who may therefore proceed to work without a sketch; here all that is begun in the morning must be completed in the evening; and that almost without cessation of labour, while the plaster is wet; and not only completed in form, but also, a difficult, nay, almost impossible task, without a well-prepared sketch, must be performed, viz., the part done in this short time must have so perfect an accordance with what follows, or has preceded, of the work, that when the whole is finished, it may appear as if it had been executed at once, or in the usual mode, with sufficient time to harmonize the various forms and tones of colour. Instead of proceeding by slow degrees to illuminate the objects, and increase the vividness of the colours, in a manner somewhat similar to the progress of nature in the rising day, till at last it shines with all its intended effect, which is the course of painting in oil, the artist working in fresco must at once rush into broad daylight, at once give all the force in light, and shade, and colour, which the nature of his subject requires, and this without the assistance (at least in the commencement) of contrast to regulate his eye; so that here, as has been said, a well digested and finished sketch seems indispensably requisite.”
The custom of decorating walls with paintings is very ancient. Those discovered by Belzoni, among the royal tombs of Egypt, prove the existence of the art among the Egyptians many centuries before the Christian era. There is also abundant evidence that it was practised by the Etruscans and Romans. But the more common practice up to the time of Augustus seems to have been to paint the walls of houses of one single colour, and to relieve this with fantastic ornaments. According to Pliny, Augustus was the first to suggest the covering of whole walls with pictures and landscapes. About the same time a painter named Ludius invented that style of decoration, now called arabesque or grotesque, many beautiful examples of which have been discovered at Pompeii and other places. The invention of the Arabesque style, as its name implies, has been improperly claimed for the Arabians of Spain; whose religion forbidding the representation of animals, they employed foliage, stalks, stems, tendrils, flowers, and fruit, in a variety of forms and combinations, with which they adorned the surfaces of their buildings. Hence the fanciful combinations of natural objects occupying a flat surface came to be called Arabesque, although it differed so much from the Mohammedan compositions as to contain animals real or fabulous. That the term is badly chosen, especially as applied to the fanciful enrichments on the walls of Pompeii, &c., will be seen from the fact that such ornaments were invented and executed long before the sons of Ishmael had learned to draw. The term grotesque is less objectionable: it is derived from the subterranean rooms (grotte) in the baths of Rome, in which those specimens of ancient art were found, from which Raphael derived the plan of the beautiful frescos which adorn the piers and pilasters of the arcaded gallery of the palace of the Vatican, called, in honour of the artist, “Le Logge di Raffaelle.”
The practice of Fresco Painting may be conveniently considered under the following heads:—1. The cartoon. 2. The preparation of the wall. 3. The process of painting. 4. The colours and implements. The methods as adopted by different artists are of course subject to variation; but as general principles are not altered by variations in those details which conduce to the same end, so the following may be taken as an accurate exposition of the practice of the art.
1. The Cartoon. Since the artist cannot without injury retouch a fresco painting, it is necessary that every part of the design be decided on by preparatory sketches finished of the full size, from which the fresco may be transferred, by tracing to the wall. When the painting is very large, the whole composition of the full size is sometimes divided into two or more cartoons.
In the preparation of a cartoon, a strong cloth is stretched on a frame, as if to be prepared for painting; paper is then firmly glued on the cloth. When this is dry, a second layer of paper is attached by glue. The edges of the separate sheets, where they overlap, are scraped, so as to preserve an even surface. The surface is then prepared for drawing with size and alum.[7] The drawing is made with charcoal, and when finished is fixed by wetting the cloth at the back with cold water, and then steaming the drawing in front. The steaming is performed with a tea-kettle with two or three spouts, kept boiling by the flame of a spirit lamp; by this means the charcoal is incorporated with the melted glue, and a solid surface like that of a picture is produced.
From this finished drawing the outline is traced on oiled paper. As much of this working outline as can be finished in one painting is then nailed to the wet wall, and the forms are again traced with a sharp point, whereby an indented outline is produced on the soft plaster. According to another method, the paper to be applied to the wall is placed behind and in close contact with the finished cartoon; the outlines of the latter are then pricked, and a similar pricked outline is thus produced on the paper behind. This pricked paper is then made the working drawing: it is fastened to the wall, and dusted with a little bag filled with black or red dust; this leaves a dotted outline on the wall. This method is sometimes adopted for small works, and the advantage of it is that it leaves the surface of the plaster undisturbed. The first mode is, however, generally preferred; since it insures the best and most decided outline, and preserves the finished cartoon uninjured.
Cartoons prepared for fresco may be seen in the National Gallery: those at the head of the staircase are by Agostino Caracci. In one of these (the Triumph of Galatea) the pricked outline is very apparent; as also in the fragment of the Cartoon by Raphael, (the Murder of the Innocents,) also in the National Gallery. In many celebrated Italian frescos the indented outline, produced by tracing, is apparent.
In addition to the cartoon it is desirable to have a coloured sketch of the whole composition.
2. The preparation of the Wall. The greatest obstacle to the permanence of fresco painting is damp: hence, if the wall to be painted is covered with old mortar, the ingredients of which are unknown, this coat should be entirely removed until the solid brick or stone is laid bare. The rough coat then applied is composed of river-sand and lime, and of such thickness as is generally used in preparing the walls of dwelling-houses. The surface of this coat should be rough, but not uneven. Thus prepared, the wall should be suffered to become perfectly dry and hard; the longer it remains in this state the safer it will be, especially if the lime used was in the first instance fresh. In that case two or three years should elapse before the process of painting is commenced.
The preparation and seasoning of the lime is one of the essential conditions of fresco painting. At Munich it is made and kept as follows:—A pit is filled with clean burnt limestone, which is slaked, and then stirred continually till it is reduced to an impalpable consistence. The surface having settled to a level, clean river-sand is spread over it to the depth of a foot or more, so as to exclude the air, and, lastly, the whole is covered with earth. It is allowed to remain thus for at least three years before it is used, either for the purposes of painting (lime being the white pigment) or for coating the walls.