Silver stain.
(2) The Invention of Silver Stain.—In the early years of the fourteenth century an important addition was made to the technical resources of the glass painter by the discovery that if white glass is painted with a preparation of silver—oxide or chloride may be used, or even silver in its metallic form, though that is less convenient—and then subjected to the heat of the kiln, the parts so painted will be found to be stained yellow, pale or dark according to the amount of silver used and according also to the composition of the glass. This is a process quite different from enamelling. It is a true stain, actually penetrating the glass to a slight degree and quite indelible except by the perishing of the glass itself. The oxide or chloride of silver is only mixed with other substances, such as yellow lake, for convenience of application.
Its first appearance.
Precisely when and where the invention was made and first used we have no means of knowing. We may dismiss the story of the glazier from whose coat a silver button dropped on to the glass he was putting into the kiln, partly because the artist of whom the story is told, one James of Ulm, who worked in Italy and was beatified after his death, was not born till more than a hundred years later. It appears in York Minster, used very sparingly and tentatively, soon after 1300. I am not sure that there are any examples in France that can be dated quite so early, but it was certainly used there by 1310. Its first use was limited to such matters as differentiating the hair, or gold crowns, of figures from their faces, but the nave windows of York Minster show a progressive increase in its use. Yellow pot-metal is there still used for the larger pieces of yellow in the canopy, but an examination of the details in Plates [XVII.], [XVIII.] will show that stain is used in places to gild the crockets of the white pinnacles, the beak and claws of the white eagle in the border of [XVII.c], and the flowers in the lower part of the border in [XVII.a]. The pieces that are yellow all over may, I think, be assumed to be pot-metal. It is not, however, till one gets well on in the century, to 1330 or 1340, that one finds such a free use of the stain in the grisaille as that in the windows at St. Ouen at Rouen, of which the detail is given in Plates [XXVI.]-[XXX.]
Combination of figures and grisaille.
(3) The Combination of Figures and Grisaille.—This is one of the most noticeable developments of the period. As I have said, it is occasionally attempted in the preceding style towards the close of the period, but in the fourteenth century it is the rule. Small windows are sometimes still filled entirely with colour, but nearly every window of any size, especially in the early part of the century, contains a large proportion of grisaille. In the nave of the Church of St. Pierre at Chartres ([Plate XXIII.]) the same principle is followed as in the earlier work in the choir, namely, the arranging of the figure-work and grisaille so as to form vertical stripes of alternate white and colour. This plan, however, was not persisted in. The numerous vertical lines formed by the mullions in the newer style of architecture required horizontal lines to balance them, and accordingly we find the usual method in fourteenth century windows is for the coloured masses to be ranged in horizontal bands running right across the window through all the lights. [Plate XXV.] from St. Ouen at Rouen shows a very typical window of the period. Sometimes there was, as here, one row of coloured panels, sometimes two or more as in the nave of York Minster. It will be noticed that in order to blend the white and colour satisfactorily the designer includes a good deal of white among the colour and a good deal of colour among the white. This latter is no longer dispersed through the white in coloured threads, half suspected, but is collected into bosses and borders where its effect is strong enough to support the principal masses. In fact the key-note of the design—namely, the strong contrast of light and dark in flat masses, necessitated by the combination of colour and grisaille—is repeated everywhere in detail throughout the window of which the parts are thus brought into harmony with the whole.
The borders.
This same idea leads to a complete change in the character of the borders. The running scroll work of the preceding age would no longer be appropriate; the vertical lines need breaking rather than emphasizing, and the design of the border usually takes the form of alternate blocks of colour and white or yellow. [Plate XXVIII.] shows some typical borders from Rouen, borders typical of English as well as French work. It will be noticed that the coloured pieces are usually left blank while the white and yellow are decorated with patterns or foliage blocked out with solid black. The ornament of the tracery lights, which by the way are usually kept pretty full of colour, is designed on the same principle. It consists, in fact, of borders tightly curled up with, sometimes, in the larger lights, a figure or a small coloured medallion in the centre containing a head.
The bosses.
The intervals formed by the regular spacing of the thick iron frame-bars are further emphasized by the placing of a coloured boss or small medallion midway between each. This arrangement in some form or other is almost universal in fourteenth century grisaille, the panels contained between the frame-bars being in fact the units of the design. Some of these bosses from Rouen are shown in Plates [XXVI.], [XXVII.], [XXIX.] Here they are purely fantastic in design, but elsewhere, as at York, they frequently have an heraldic motive or even take the form of shields of arms ([Plate XVIII.]). Heraldic motives are very commonly used too in the borders, as may be seen in the details from York Minster in [Plate XVII.], the charges from the shield being repeated all up the border, relieved against, or sometimes alternating with blocks of the colour of the field. Symbolic objects such as chalices are sometimes used in the same way, and occasionally we find borders formed of a succession of little figures under canopies, as in the very elaborate example from York in [Plate XVIII.]