[§ 105, Enamels over Reliefs, ante, p. [276].]

Coloured vitreous pastes are among the most valuable materials at the command of the decorative artist, and are employed in numerous crafts, as for example for the glazes of keramic products including floor or wall tiles, for painted glass windows, for glass mosaic, and for enamel work. The glass is tinged in the mass with various metallic oxides, one of the finest colours being a ruby red gained from gold. Silver gives yellow, copper a blue-green, cobalt blue, manganese violet, and so on. Tin in any form has the property of making the vitreous paste opaque. The material is generally lustrous, and it admits of a great variety in colours some of which are highly saturated and beautiful. It is on the lustre and colour of the substance, more than on the pictorial designs that can be produced by its aid, that its artistic value depends.

The difference between opaque and transparent coloured glass is the basis of a division that can be made among the crafts which employ the material. If the glass be kept transparent the finest possible effect is obtained from it in the stained glass window where the colours are seen by transmitted light. A similar effect is secured on a minute scale in that form of enamel work called by Labarte ‘emaux à plique à jour,’ or ‘transparent cloisonné enamel,’ in which transparent coloured pastes are fused into small apertures in metal plates. Old examples in this kind are very rare, but modern workers seem to reproduce it without difficulty. On the other hand transparent or more usually opaque vitreous pastes in thin films form many of the so-called ‘glazes’ which give the charm of lustre and colour to so many products of the potter’s art. The most effective use of opaque coloured glass is in wall mosaic, where it is seen by reflected light, and owes its beauty to its lustrousness as well as to the richness and variety of its hues. Between these two crafts of the stained glass window and mosaic comes that of the enameller, who makes use of vitreous pastes both in an opaque and a transparent condition. The identity of the materials in these different uses is shown by the fact that Theophilus, Bk. II, ch. 12, directs the enameller to pound up and melt for his incrustations the very cubes used in old mosaics, or as he puts it ‘in antiquis aedificiis paganorum in musivo opere diversa genera vitri.’ Enamel work consists in fusing these coloured pastes over surfaces that are generally of metal, the different tints being either distinctly separated by divisions, or else running beside each other, or again interpenetrating like the colours in a picture. Hence there are two main divisions of the enameller’s craft, the painted enamel where the colours are fused on to the metal but produce an effect similar to that of a painting executed with the brush, the special advantage of the enamel being its lustre; and the encrusted enamel, where the effect is more like that of mosaic. Vasari would have thoroughly appreciated the painted enamels, known generally as enamels of Limoges, which are complete pictures, but, though Cellini mentions them, they originated north of the Alps and only came into general vogue after Vasari’s time. The incrusted enamels are earlier, and of these he only describes one particular kind that had its home specially in Italy.

The earliest known enamels, whether Western or Byzantine or Oriental in origin, have the different colours separated in compartments divided from each other by ridges of metal which give the lines of the design. These so-called ‘champlevé’ and ‘cloisonné’ enamels there is no need to discuss, but it may be noted that the pastes used in them, though highly lustrous, are opaque, and cover completely the metal over which they are laid. The enamel described by Vasari differs from these earlier enamels in compartments in that the pastes are transparent, so that the ground shows through. The divisions between the colours also are not so marked. In this kind of work transparent vitreous pastes are fused over a metal ground that has been chased in low relief, so that the light and shade of the relief shows through the transparent coloured film. The work is very delicate and on a small scale, and the ground is nearly always gold or silver. A slight sinking is made in a plate of one of these metals where the enamel is to come, and at the bottom of this sinking the subject is carved or chased in very low relief, so low indeed that Cellini compares the height of it to the thickness of two sheets of paper (Dell’ Oreficeria, c. III). The transparent enamels are then fused over the different parts of the design, the contours of the figures or objects being just allowed to show as fine lines of metal between the different colours.

Examples of this work are rare, but the Victoria and Albert Museum and the British Museum have some good specimens. Transparent enamels are used also in other ways, and are sometimes arranged in apertures (see above) so as to show by transmitted light. Labarte’s Histoire des Arts Industriels is still indispensable as an authority on various kinds of enamel work, though there is a whole literature on the theme.

INDEX

For buildings and permanent monuments at Florence, Rome, etc., see under the names of the respective cities.

The references are to pages. The upright numerals refer to the text, the sloping ones to the commentary.

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