Such would be the figures alluded to by Lucian, or by Lexiphanes when he says, “If you cull the flower of all these various beauties, you will in your eloquence be like those makers of figures in wax and clay [or argilla] in the Forum, colored outside with minium and blue, and inside only fragile clay.”
According to this interpretation of the passage in Pliny, it not only becomes intelligible as a whole, but is consistent and without contradiction; whereas, if we suppose that he meant to indicate the process of casting in plaster, his statements are not only entirely obscure and inconsecutive, but ignorant and contradictory.
II.
In the previous chapter we have critically considered the text of Pliny bearing upon the question whether the ancient Greeks and Romans were acquainted with the art of casting. Let us now proceed to some general considerations as to the probability that this art was known and practiced by them.
In the first place, the distinction between modeling and casting must be constantly kept in mind, and care must be taken not to confound the two totally different terms “mould” and “model.” That gypsum was used in modeling there can be no doubt, and it is quite possible that it may have been used to fill prepared moulds of stone, terra cotta, or other materials for the making of ectypa. There is indeed no proof of this; but as we know that moulds were made and cut in stone, into which clay was pressed, to be then withdrawn and baked for ectypa with which to adorn houses, so also it is possible that gypsum may have been used for this purpose. This, however, is merely a supposition, and the fact that none of them have ever been found in plaster renders it highly improbable. In these ectypa of clay, as well as in the impressions taken from them, there are no indications of anything like what we call a piece-mould, composed of many sections; and whenever there are under-cuttings in the ectypa, which could not be withdrawn from the mould and which would fasten them into it, these parts of the ectypa are invariably worked by hand. For instance, in the collection of Mr. Fol in Rome there are several terra cotta figures of low relief evidently stamped from a mould, which are appliqué, or fastened subsequently to the cista of which they form a part. The sutures under each figure are still visible, but they are all corrected and worked by hand after being withdrawn, and have evidently suffered in being removed from the mould. In the same collection there are several specimens of plaster reliefs, with such deep under-cuttings that they could not have been withdrawn from a single piece-mould; but all these under-cuttings are freely worked by hand, showing plainly that they were not in the stamp or mould; and it is also clear that they were afterwards worked over with fluid plaster, the edges and flats of which have not been rounded, but left as it was freely laid on by hand. It is probable that in these cases plaster was pressed into a mould in the same manner as clay, and afterwards worked up and finished. But the slightest examination will show clearly that if a mould was employed to give a general form to them, it certainly was not a piece-mould; and that they are not castings in the modern sense of the word, but only rude stamps.
These are the only specimens, however, so far as we are aware, of any such use of plaster for low-relief ornaments,—the ectypa which have been preserved to us being invariably of baked clay. If plaster had been used for this purpose, we should expect to find casts in the interior of houses or tombs, where they would be protected from the weather, and where they could be easily introduced into the walls and ceilings. But though elaborately ornamented designs in relief, worked in gypsum, are to be found still fresh and uninjured on the ancient tombs and baths, all of them were freely and rapidly modeled by hand while the gypsum was still fresh and plastic, and not a single specimen of cast plaster has been found. It is but a few years since the tombs in the Via Latina were opened, and in two of them the ceilings, divided into compartments, were covered with rich and fantastic designs of flowers, fruit, arabesques, groups of imaginary animals, sea-nymphs, and human figures; the designs varying in each compartment, and all modeled in the plaster with remarkable vivacity and spirit: not one of them was cast. So in the houses at Pompeii, not a vestige of a figure or ornament cast in plaster has ever been found,—nor a mould in plaster; and when one considers that, being completely protected, they would naturally have survived as well as other far more fragile and destructible objects which have been preserved, the evidence is almost absolute that they never could have existed there. If so, it is in the highest degree probable that they existed nowhere. It would seem plain, then, that even the first, simplest, and most natural processes of casting in gypsum were unknown to the ancients, for no other process is so easy and simple as to fill a flat mould with plaster and then remove it, provided there are no under-cuttings. In doing this, however, there is a slight practical difficulty if the mould is in one piece, as the least under-cutting would render it impossible to remove the cast without injury or breakage. Indeed, though there were no under-cutting, it would at least be very difficult to remove the plaster from a mould in one piece. Clay would be removed with far greater ease because of its pliancy, and any cracks or imperfections could be at once remedied; add to this that baked clay is one of the most enduring of materials, and we have the probable reasons why the ancients used it instead of gypsum. But whatever may have been their reasons, it is perfectly clear that they did use clay; and we have no evidence that they ever used plaster.
This use of gypsum to take impressions from flat moulds is suggested by Theophrastus, it would seem, in his treatise on mineralogy,[18] in which he says that plaster “seems better than other materials to receive impressions.” The term ἀπόμαγμα means nothing more than an impression, such as one makes in wax from a seal ring, and such as is common still in plaster; it is to this use that he seems to refer. He does not say, however, that gypsum was really put to this use; and if it were, it would advance us little in our inquiry, since any material which is soft will receive an impression, whether it be bread, pitch, clay, wax, or any similar substance.
But the step from this simple process of stamping in a shallow mould to casting from life or from the round is enormous. The difficulties are multiplied a hundred-fold. It is no longer a simple operation, but a nice and complicated one. The part to be cast must first be oiled or soaped, then covered with plaster of about the consistency of rich cream, then divided into sections while the material is still tender, so as to enable the mould to be withdrawn part by part without breakage, then allowed to set, then removed, oiled or soaped on the interior surface, the parts all properly replaced, fluid plaster poured into the mould,—and finally, after the cast is set, the mould must be carefully removed by a hammer and chisel. This is an elaborate process as applied to an arm or a hand, but when applied to a living face it is not only difficult but disagreeable, and unless due care be used it may be dangerous; and after all a cast from the face is hard, forced, and unnatural in its character and impression, however skillfully it may be done, and can only serve the sculptor as the basis of his work. Yet if the common interpretation of the passage in Pliny be accurate, this is the process which was invented and practiced by Lysistratus, and by means of which he made portraits. Credat Judæus! With all our knowledge and practice, we do not find this to answer in our own time.
But to cast from a statue in clay is still more difficult and complicated; there the extremest care and nicety are required in making the proper divisions, in extracting the clay and irons, recommitting the sections, and breaking off the outer shell of the mould. In fact, the modern process is so complicated that no one can see it without wondering how it ever came to be so thought out and perfected, or without being convinced that it must have been slowly arrived at by many steps and many failures.
That statues were modeled in plaster by the ancients there is no doubt. Pausanias mentions several;[19] and Spartianus[20] also speaks of “Three Victories” in plaster, with palms in their hands, erected at one of the games,—and says that on one of the days of the Circensian games when according to common custom they were erected, the central one on which the name of Severus was inscribed, and which bore a globe, was thrown down by a gust of wind from the podium, and that another bearing the name of Geta on it also fell and was shattered to pieces.