These imitations of metal were largely made in southern Italy, a district which enjoyed close artistic relations with Etruria, and we have already seen that the same principle had long been in vogue among the Etruscans. Hence it is not surprising that an important centre of pottery manufacture should have sprung up in Etruria, in the and century b.c., which for many years set the fashion to the whole Roman world. But before discussing such products it may be as well to say something on the technical character, shapes and uses of Roman pottery in general.
Technical Processes.—Roman pottery regarded in its purely technical aspect is in some ways better known to us than the Greek, chiefly owing to extensive discoveries of kilns and potters’ apparatus in western Europe. It may be classified under two heads, of which only the second will concern us for the most part as yielding by far the greater amount of material and interest: (1) the plain, dull earthenware used for domestic purposes, and (2) the fine, red shining wares, usually known to archaeologists as terra sigillata, clay suited to receive stamps (sigilla) or impressions.
For both classes all kinds of clay were used, varying somewhat in different regions, and ranging in colour when fired from black to grey, drab, yellow, brown and red. The clays varied greatly in quality; most of the pottery made in southern Gaul was fashioned from the ferruginous red clay of the Allier district, but at St-Remy-en-Rollat and in that neighbourhood a white clay was used. In Italy we find a carefully levigated red clay in use, great care being devoted to its preparation and admixture. But apart from decoration and style there is a great similarity in the general appearance of the Italian and provincial pottery made under Roman influence, and it is often very difficult to decide whether the vases were manufactured where they had been found or were imported from some famous centre of manufacture. The secret of the glossy red surface seems to have been common property and found its way from Italy to Gaul, Spain and Germany, and perhaps even to Britain.
The manner in which this glossy red surface was produced has been a much-disputed question, some, as for instance Artis, the excavator of the Castor potteries in Northamptonshire, claiming that it was a natural result obtained in the baking, after polishing of the surface, by means of specially contrived kilns. But it is now generally agreed that it was artificial. It is true that the Roman lamps and many of the commoner wares have a gloss produced by polishing only, varying in colour and brightness with the proportion of iron oxide in the clay and the degree of heat at which the pieces were fired. But the surface finish of the finer or terra sigillata wares is something quite distinct, and reaches a high and wonderfully uniform perfection.
It is possible that the technical secret of the potters of the Roman world was only a development from the practice of the Greeks, but it does seem as if the finer Roman wares were coated with a brilliant glossy coating so thin as to defy analysis, yet so persistent as to leave no doubt of its existence as a definite glossy coat. Repeated attempts have been made to determine its nature by analysis, but chemists ought to have known better, for the coating is so thin that it is impossible to remove it without detaching much more body than glaze. Examination shows it to be much more than a surface polish or than the gloss of the finest Greek vases, and we shall have to wait for a final determination of its nature until some one who is at once a chemist and a potter can reconstruct it synthetically. Whatever its nature and method of production, it is certain that the glaze itself was a transparent film which heightened the natural red colour of the clay, until in the finest specimens it has something of the quality of red coral.
In the manufacture of vases the Romans used the same processes as the Greeks. They were all made on the wheel, except those of abnormal size, such as the large casks (dolia), which were built up on a frame. Specimens of potters’ wheels have been found at Arezzo and Nancy, made of terra-cotta, with a pierced centre for the pivot, and bearing small cylinders of lead round the circumference to give a purchase for the hand and to aid the momentum of the wheel. For the ornamental vases with reliefs an additional process was necessary, and the decoration was in nearly all cases produced from moulds. The process in this case was a threefold one: first the stamps had to be made bearing the designs; these were then pressed upon the inside of a clay mould which had been previously made on the wheel to the size and shape required; finally, the clay was impressed in the mould and the vase was thus produced, decoration and all. Handles being of rare occurrence in Roman pottery, the vases were thus practically complete, requiring only the addition of rim and foot. The stamps were made in various materials, and had a handle at the back (Plate III. fig. 64). The moulds were of lighter clay than the vases, and were lightly fired when completed, so as to absorb the moisture from the pressed-in clay. Large numbers of these moulds are in existence (Plate III. fig. 61), and the British Museum possesses a fine series from Arezzo. Those discovered in various parts of Gaul have afforded valuable evidence as to the sites of the various pottery centres, as their presence obviously denoted a place of manufacture, and the value of this evidence is increased when they bear potters’ names.
Remains of kilns for baking Roman pottery[8] are very numerous in western Europe, especially in Gaul, where the best examples are at Lezoux near Clermont, at Châtelet in Haute-Marne, and near Agen in Lot-el-Gäronne. In Germany good remains have come to light at Heiligenberg in Baden, al Heddernheim near Frankfort, Rheinzabern near Carlsruhe, and Westerndorf in Bavaria. In England the best kilns are those discovered by Artis in 1821-1827 at Castor in Northamptonshire (see fig. 4).
Shapes.—As is the case with Greek vases, a long list of names of shapes may be collected from Latin literature, and the same difficulties as to identification arise in the majority of cases. They may, however, be classified in the same manner; as vases for storing liquids, for mixing or pouring wine, for use at the table, and so on. In addition Varro and other writers have preserved a number of archaic and obscure names chiefly applied to the vases used in sacrifices.
The principal vases for storing liquid or solid food were:—The dolium, a large cask or barrel of earthenware; the amphora, a jar holding about six gallons; and the cadus, a jar about half as large as the amphora. The dolium had no foot, and was usually buried in the earth; it was also used for purposes of burial. The amphora corresponds to the Greek wine-jar of that name, and had, like its prototype, a pointed base. Many examples were found at Pompeii stamped with the names of consuls (cf. Hor. Od. in. 21. I), or with painted inscriptions relating to their contents. The cadus is mentioned by Horace and Martial.
Of smaller vases for holding liquids, such as jugs, bottles and flasks, the principal were the urceus, answering to the Greek οἰνοχόη, the ampulla, a kind of flask with globular body, and the lagena, a narrow-necked flask or bottle. Of drinking-cups the Romans had almost as large a variety as the Greeks, and the great majority of the ornamented vases preserved to the present day were devoted to this purpose. The generic name for a cup was poculum, but the Romans borrowed many of the Greek names, such as cantharus and scyphus. The calix appears to have answered in popularity, though not in form, to the Greek kylix, and is probably the name by which the ornamented bowls were usually known. The names for a dish are lanx, patina and catinum. Another common form is the olla (Greek χύτρα), which served many purposes, being used for a cooking-pot, for a jar in which money was kept, or for a cinerary urn. The form of vase identified with this name has a spherical or elliptical body with short neck and wide mouth. Of sacrificial vases the principal was the patera or libation-bowl, corresponding to the Greek φιάλη.