Before leaving for a time the further consideration of the shield it will be convenient to refer to the very beautiful method of relieving and enriching surfaces which is called Diapering, and is a notable feature of the more elaborate kinds of heraldry. Numerous and excellent examples of its use may be found on the sculptured shields of the monuments and chantries, as well as on incised brasses, in enamels and in stained glass.
Coming into heraldic use in the thirteenth century, it was soon extensively applied to the decoration of armorial shields and especially of their fields and ordinaries. In some instances charges also were diapered, but only when they were flat in character and when the general treatment and material lent themselves to the method. In most cases it was confined to plain surfaces. The patterns were in many instances derived from those that had been employed from ancient times in textile decoration.
Whenever diapering is applied to a shield it is purely ornamental in character, and in many instances is geometrical in plan, having no forms that could possibly be mistaken for charges, and so be likely to interfere with the clear statement of the arms. The example is one of the many beautifully diapered shields that decorate the shrine of the Percies in Beverley Minster. In sculpture proper, when the design was cut out of the surface, a pattern such as that of Fig. 140 was found very suitable to the material and to the method of working it; when, however, the diaper was modelled up, as in the gesso decoration of ceremonial shields, or was incised in reverse, as in a seal, the design frequently took the form of flowing lines as the readiest means of getting the ornate effect that was required. An example of this latter method may be referred to in the Great Seal of Henry IV at p. 18, Fig. 2.
Fig. 140.—Diapered Shield from the Percy Shrine in Beverley Minster. Fourteenth Century.
In the early examples the diaper, like the semée already referred to, was treated as though it were a piece of an ornamental fabric stretched over the shield and passing behind the charges without being affected or displaced by them. The Renaissance work shows the diaper more especially adapted to the occasion, as in a Florentine shield from the Palazzo Guadagni and now in the Victoria and Albert Museum, which is beautifully decorated in raised lines of gesso which follow the outline of the figure at a little distance from it, and the rest of the decoration accommodates itself to the shape of the spaces in a manner that is especially satisfactory, as conveying the impression of being carefully designed for its particular purpose, with each part in due relation to the others.
Fig. 141.—Diapered Shield in Painted Gesso at Alloa House. The Arms of Henricus de Erskine. 1224. Geo. W. Eve.
The illuminations of the manuscripts were frequently diapered with designs drawn in lines of gold on the ground colour, and a lighter or darker tint of the ground colour was similarly employed, sometimes also in combination with gold. Indeed, the possibilities of diapering as surface decoration are almost without limit if it is reasonably handled. Its effect in enriching and adding interest to simple forms and spaces is shown in the treatment of the Arms of Henricus de Erskine (Fig. 141) and the shield of John, fifth Lord Erskine, and his wife, Lady Margaret Campbell (Fig. 142), two of the series of shields executed in painted gesso for the hall, Alloa House, Clackmannanshire. It is very useful in monochrome, as in engraving for instance, as a means of distinguishing contiguous spaces; in the way that line tints were employed to do before a colour value was ascribed to them. Being, of course, completely under control to be employed or omitted at will, it has none of the objections of the tincture lines.
