An establishment of this kind implies several buildings. The vase turners or makers would be in a separate room from the painters. One or more ovens would be required in a court, with a shed for the storage of raw materials, and for kneading and refining the clay. Lastly, we must assume that there were some rooms for warehousing and a sale-room adjoining the factory, in addition to rooms for the masters and night-watchmen. No matter how modest the staff, it would amount to fifteen or twenty persons, counting not only those in charge of the factory, but labourers and stokers. Upon the hydria at Munich (Fig. 4), in a painting necessarily restricted, we can count eight persons. Upon the vase from Ruvo (Fig. 2) the studio contains four workers--three men and one woman--all painting. To obtain a correct idea of the staff one must at least treble this number. Hence a potter like Douris must have superintended a factory representing a commercial enterprise of some importance. We must not think of an artist, who, in his solitary studio, at his leisure and according to his inspiration, sketches subjects or forms for vases, and leaves the execution to others. We must not forget it is an industry. This practical purpose must profoundly influence one’s opinions as to the nature of the potter’s studies, his manner of composing, and the profit he expects from his enterprise. We will not discuss points of technique which demand too detailed an enquiry, and would raise questions not yet solved. Let us think of the materials as gathered in the hands of the craftsman: clay carefully chosen and refined, colours for glazing and retouching, lustres intended to brighten the natural colour of the clay, and the black for the design, wheels and moulds, rules and compass, sharp points for sketching, brushes of all kinds, etc. The most commonly used and most valuable ingredient is the black glaze, the composition of which is still unknown; its basis is oxide of iron. It is used for drawings on red clay, to trace features, persons, accessories and decorations, and to cover the background. It is to the Greek what Indian ink is to the draughtsman of Japan. In baking, it takes on a warm, velvety tone, sometimes a little olive, sometimes it becomes in the flames a little yellow or red. It is brightened by a brilliant lustre which frequently produces the effect of a mirror, but it never has the cold or waxy tone which disfigures modern imitations of antique vases. It is thick and rich, and forms, after drying, a slight prominence perceptible to the finger. Lastly, it is indestructible, even by acids, and does not change with time, unless the surface of the clay beneath it has been touched by damp, in which case it flakes off.