In decorative work the use of contrast in the relief of parts of a design is often useful and effective, as, for instance, the dark shading or treatment in black or flat tone of the alternating under side of a turn-over leaf border.
The decorative value of this principle is recognized by heraldic designers in the treatment of the mantling of the helmet, which in earlier times is treated simply as a hanging or flying strip of drapery with a lining of a different colour, by which it is relieved as it hangs in simple spiral folds. This ornamental element became developed by the designers of the fifteenth and sixteenth centuries into elaborate scroll designs springing from the circlet of the helmet and surrounding the shield: but the principle of the turned-up lining remained, often variegated and enriched with heraldic patterns (see illustrations, pp. [172], [173]).[4]
[4] The increased importance given to the mantling in later times may have been due to the disappearance of the housings of the knight's horse and his surcoat, which originally displayed his arms and colours. The mantling of later times displayed the heraldic colours of the knight, when, being clad in plate armour, there was no other means of displaying them except on the shield. Decoratively, of course, the mantling is of great value to the heraldic designer, enabling him to form much more graceful compositions, to combine diverse and rigid elements with free and flowing lines and masses, and to fill panels with greater richness and effect, whether carved or painted, or both.
Use of Diapered Backgrounds
The principle, too, of counterchange in heraldry answers to our principle of relief by contrast, and though its chief charm lies in its ornamental range of form and colour combinations, it can be expressed in black and white, and it remains a universal principle throughout decorative art. The decorative effect and charm of the relief of large and bold forms upon rich and delicate diapers is also an important resource of the designer. The monumental art of the Middle Ages affords multitudes of examples of this principle in ornamental treatment. The miniaturist of the twelfth and thirteenth centuries constantly relieved his groups of figures upon a diapered ground. The architectural sculptor relieved the broad masses of flowing drapery and the bold projection of his effigies and recumbent figures by delicately chiselled diapers upon the surface of the wall behind them. This treatment may frequently be seen in the recessed tombs of the fourteenth century.
The incisor of memorial brasses, again, more especially in continental examples, shows a fondness for the same principle. The long vertical lines of drapery of ladies and ecclesiastics, the broad masses of the heraldic surcoat, or armour of the knights, the rich and heavy furred gowns of the burghers, are often relieved upon beautiful diapered or arabesque grounds, generally embodying some heraldic device, motto, or emblem of the person or family whose tomb it ornaments. Such decoration is strictly linear, yet within its own limits, and perhaps because of them, we find in this province of design extremely admirable work, no less for delineation of character and decorative treatment than for ornamental invention controlled by strict economy of line.