The pottery of which we have spoken in Part I. has no decoration; Salvetat called it simple pottery. Part II. is devoted to what the same author called made-up pottery; it is distinguished from the former kind by its decoration.
A decorated piece of pottery is one whose surface receives an earthy, vitreous, or metallic coating, which modifies its appearance and gives it new properties; the decoration may be reduced to a simple engobage, or be composed of brilliant colours, like the magnificently painted panels with which walls are covered.
The different methods of decorating pottery comprise decoration with engobes, or dips with glazes, with colours, or with metals.
Decoration with engobes is effected by means of white or coloured earthy matters with which pottery is totally or partially coated, so as to modify its colour and its appearance, to give it sometimes new properties with a view to applying a glaze, or finally to produce decorative effects by using variously coloured engobes.
Decoration with glazes is effected by means of vitreous or opaque, coloured or colourless substances, which are fixed by fire to the pottery to render it impervious, give it a brilliancy which will enhance its colouring, or on the other hand hide or mask that colour when it is not an agreeable one.
Decoration with colours is effected by applying to the pottery metallic oxides, mixed or not with verifiable substances and fixed under or over a glaze. The effect produced is very different from that produced by enamels, and permits of our distinguishing them, although they are often confused together.
Decoration with metals is obtained by applying them according to the effect required, either in the metallic state, when we wish to produce the effect called metallic lustre, or in the form of salts.
Having given these definitions, we can now study in detail the various styles of decoration.