process? Furthermore, Berger holds the astonishing theory
that on the self-coloured surfaces of Pompeian and Roman
plastered walls the colour was not apphcd, as in the fresco process,
to the surface of the final coat, but was mixed up with the actual
material of the intonaco so that this was a coat of coloured
plaster. This is of course a matter susceptible of ocular proof,
but the actual fragments of ancient coloured stucco referred
to by Berger afford a very slender support to the hypothesis,
whereas everyone who, like the present writer, possesses such
fragments can satisfy himself that in almost every case the
colour coat is confined to the surface. The writer has a fragment
of such stucco from Rome, coloured with vermilion, and
here there is clear evidence that some substance has soaked into
the plaster to the depth of an eighth of an inch, as would be the
case in the " ganosis " of Vitruvius. The part thus affected is
yellowish and harder than the rest of the plaster. A careful
chemical analysis, kindly made for the purpose of this article
by Principal Laurie of Edinburgh shows that, although the small
quantity of the material available makes it impossible to attain
certainty, yet the substance may possibly be wax with the
slight admixture of some greasy substance. On the other hand
all the writer's other specimens show the colour laid on to all
appearance " a fresco." The evidence of the coloured plaster
in the house of about the 2nd century B.C. on Delos is wholly
against Berger's view. The writer has many specimens of this,
and they are all without exception coloured only on the surface.
It is true that there are certain difficulties connected with
Pompeian fresco practice, but the description of the process
as a wet process in Vitruvius and Pliny is so absolutely unmistakable
that Berger's theory must without hesitation be
rejected.
The history of the fresco technique remains at the same time obscure. Here again Berger offers an interesting suggestion which cannot be passed over in silence. If the Pompeian technique, as he beUeves, be a wax process on dry plaster, followed by some form of tempera, how did the fresco technique, which is known both in East and West in the later medieval period, take its rise? The early medieval age was not a time when a difficult and monumental technique of the kind is likely to have been evolved, but Berger most ingeniously connects it with that of mosaic work. In mosaic the wall surface is at first rough plastered and a second and comparatively thin coat of cement is laid over it to receive and retain the cubes of coloured glass, only so much cement being laid each morning as the worker will cover with his tesserae before night. It was the practice sometimes to sketch in water-colours on the freshly laid patch of cement the design which was to be reproduced in mosaic, and Berger points to the incontestable fact if this sketch were allowed to remam without being covered with the cubes it would really be a painting in fresco. This is the way he thinks that the frescoe practice actually began, and the period would be that of the decline of mosaic work in the West as the middle ages advanced.
In spite of the attractiveness of these suggestions, we must reaffirm the view of this article that the testimony of Vitruvius is conclusive for the knowledge by the Romans of the early empire of the fresco technique. Why we do not find evidence of it far earlier cannot be determined, but it is worth noting that the success of the process depends on the plaster holding the moisture for a sufficient time, and this it can only do if it be pretty thick. In ancient Egypt and Mesopotamia, for example, the plaster used as painting ground was very thin, and especially in those hot climates would never have lent itself to fresco treatment. On the other side, the dechne, and perhaps temporary extinction, of the technique in the early middle ages may be reasonably explained by the general condition of the arts after the break-up of the Roman Empire of the West.
To return now to the technical questions from which this historical digression took its rise, it will be easily seen that the process of painting in fresco must be a rapid one, for it must be completed before the plaster has had time to dry. Hence only a certain portion of the work in hand is undertaken at a time, and only
so much of the final coat of plaster, called by the Italians intonaco is laid by the plasterer as will correspond to the amount the artist has laid out for himself in the time allowed him by the condition of the plaster. At the end of this time the plaster not painted on is cut away round the outline of the work already finished, and when operations are recommenced a fresh patch is laid on and joined up as neatly as possible to the old. In the making of these joints the ancient plasterer seems to have been more expert than the Italians of the Renaissance, and the seams are often pretty apparent in frescoes of the 15th and 16th centuries, so that they can be discerned in a good photograph. When they can be followed, they furnish information which it is often interesting to possess as to the amount that has been executed in a single day's work. Judging by this test, Mr Heath Wilson, in his Life of Michelangelo, computed that on the vault of the Sistine Michelangelo could paint a nude figure considerably above life size in two working days, the workmanship being perfect in every part. The colossal nude figures of young men on the cornice of the vault at most occupied four days each. The " Adam " (fig 34, Plate X.). was painted in four or perhaps in three. A day was generally occupied by the head of such figures, which were about 10 ft. high. Raphael, or rather his pupils, it is thus calculated, painted the Incendio del Borgo, containing about 350 sq. ft., in about forty days, the group of the young man carrying his father occupying three. The group of the Three Graces in the Villa Farnesina took five days at most. Luini, a most accomplished executant, could paint " more than an entire figure, the size of life, in one day " (Second Report, p. 37). It has been noticed as one of the difficulties about the Pompeian frescoes, that joints hardly occur, or at any rate that larger surfaces of plaster were covered by the painter at a single time than was the case among Renaissance artists, and a conjectural explanation has been offered based on the fact that the ancient plaster ground, laid on in many successive coats while in each case the previous one was still humid, was thicker and would hold more moisture than the more modern intonaco, and would accordingly allow the artist longer time in which to carry out his work. Alberti, Armenini, and Palomino only contemplate one or two thin coats over the original rough cast, while Cornelius and his associates, who revived the process early in the 19th century, speak of an intonaco over the rough cast only about a quarter of an inch thick. A piece of plaster ground from Raphael's Loggie in the Vatican was found to be quite thin, and Donner calculated that the ancient grounds were on an average 3 in. thick, the modern only a little over 1 in. On such grounds work had necessarily to be finished within the day, and Cennino expressly says (ch. 67): " Consider how much you can paint in a day; for whatever you cover with plaster you must finish the same day." Hence almost invariably in ItaUan fresco practice every join means a new day's work. At Pompeii the plaster, it is thought, might have remained damp over night. In the Mount Athos Handbook tow was to be mixed with the plaster, undoubtedly to retard its drying.
This necessarily rapid execution gives to well-handled frescoes a simplicity and look of directness in technique that are of the essence of the aesthetic effect of this form of the art. Hence Vasari is right when he extols the process in the words, " of all the ways in which painters work, waU-painting is the finest and most masterly, since it consists in doing upon a single day that which in other methods may be accomphshed in several by going over again what has been done. . . . there are many of our craft who do well enough in other kinds of work, as for example in oil or tempera, but fail in this, for this is in truth the most manly, the safest, and most solid of all ways of painting. Therefore let those who seek to work upon the wall, paint with a manly touch upon the fresh plaster, and avoid returning to it when it is dry " (Opere, ed. Milanesi, i. 181).
The process gives the artist another advantage in that his painting, being executed in the very material of the surface itself, seems essentially a part of the wall. It is lime painting on a hme ground, and fabric and enrichment are one. This
