When we come to designing for stained glass we should still bear in mind the fundamental net of lead lines which forms the basis of our pattern, or glass picture, as it were: and the designer's object should be to make it good as an arrangement of line independently of the colour, while practical to the glazier.
Although lead is very pliable, too much must not be expected of it in the way of small depressions and angles: the boundary lines of the figures, which should be the boldest of all, should be kept as simple as possible, not only on this account, but because complex outlines cannot well be cut in glass. A head, for instance, is inclosed in sweeping line, and the profile defined within the lead line by means of painting. A hand would be defined on the same principle. Each different colour demands a different inclosure of lead, although in the choice of glass much variation of tint can be obtained, as in the case of pot metal running from thin to thick glass, which intensifies the colour, and many kinds of what is called flashed. Yet to the designer, from the point of view of line, glass design is a kind of translucent mosaic, in which the primal technical necessity of the leading which holds the glory of the coloured light together, really enhances its splendour, and in affording opportunities for decoration and expressive linear composition imparts to the whole work its particular character and beauty.
This after all is the principle to cling to in all designing, to adapt our designs to the particular distinctive character and beauty of the material for which they are destined, to endeavour to think them out in those materials, and not only on paper. Whatever the work may be—carving, inlays, modelling, mosaic, textiles—through the whole range of surface decoration, we should think out our designs, not only in relation to the limitations of their material, but also in their relation to each other, to their effect in actual use, and even to their possible use in association together, which, of course, is of paramount importance in designing a complete room or any comprehensive piece of decoration.
And when we leave plane surfaces and seek to invent appropriate, that is to say, expressive ornament allied to concave and convex surfaces, to the varied forms of pottery for instance, metal-work, and glass vessels, furniture, and accessories of all kinds, we shall find the same laws and principles hold good which should guide us in all design—to adapt design to the characteristics and conditions of the material, to its structural capacity, its use and purpose, as well as to use or invention in line, both as a controlling plan or base of ornament, as well as a means of the association and expression of form.