This section is from the book "A Treatise On Architecture And Building Construction Vol4: Plumbing And Gas-Fitting, Heating And Ventilation, Painting And Decorating, Estimating And Calculating Quantities", by The Colliery Engineer Co. Also available from Amazon: A Treatise On Architecture And Building Construction.
Mosaic Glass Painting. Much that has been already said may apply to the forcing of designs with colored pieces of pot metal, or, in part of these, and in part of painted white glass. Mosiac glass painting requires two cartoons; one, finished and colored, is used by the artist as a pattern, serving to determine the arrangement of the pieces of glass according to their several colors, and the manner of introducing the leaden ribs to fasten these pieces together. Each piece of glass to be introduced into the pattern must be distinguished by a separate number. The other cartoon bears only the dark outlines of the lead painting, the several parts numbered to correspond with the first, and is to be cut in pieces according to the outlines, each piece diminished in size all around by one-half the thickness of the leaden bar of the jointing, so that the pieces of glass may be cut with exactitude to their proper dimensions. The glass may be cut either with a diamond or by tracing the line of division with a red-hot iron.
189. Fig. 80 is a modern design for a stained-glass window as it appears when received from the designer. The lines on which the glass must be cut to fit it together in the leading, do not appear on the original drawing, or cartoon, as it is called, but are marked out later and cut. Each piece is then separately painted by the artist, using the cartoon as a guide, and all are then baked, or fired, in the muffle, in order to vitrify the colors and fix them in the surface of the glass. The pieces are then fitted together, secured with the lead strips, and the complete design framed in a sash, or other" support, to preserve it until it is required to place it in its final support, the window. Iron rods are sometimes secured to the leading by means of small pieces of copper wire soldered to the leads at regular intervals. These rods are spaced from 2 to 6 inches apart and tend to keep the finished design from bending in any of the joints or breaking across the small pieces of glass. They are left in place after the window is set, and should, therefore, be so placed as not to cast a shadow across the design when the window is between the observer and the source of light.
190. Glass painters had already, in the fourteenth century, begun to copy nature with some success. Light and shade then became more vigorous, and the flesh, instead of being represented, as in older specimens, by violet-tinted glass, is painted in white glass with a reddish-gray color. The pieces of glass are larger, the strips of lead placed at wider intervals; large single figures, sometimes occupying a whole window, are placed under elaborate Gothic canopies, and on a plain blue or red instead of mosaic ground. The tendency of the artist to produce work in individual form is, from the beginning of the fourteenth century, more and more observable. The decorations, which, like frames, surround the figures and the subjects, always borrowed from the architecture of the times, are, from day to day, increased, presenting a great variety of ornamental lines, often with pleasing and impressive effect.
During the greater part of the fifteenth century, a parchment roll with a verse of scripture sets forth the subject of the decoration. Blue and red hangings, introduced behind the figure, are of damasked stuffs of great richness. Borders are rare, but when found, consist of branches meager in foliage, painted upon strips of glass. In the second half of the fifteenth century, buildings and landscape in perspective are first brought in, while in the sixteenth century, the artist skilfully renders graceful compositions, with depth of background, trees, fruits, and flowers.
Painting Gothic borders on the mosaic was, at first, limited almost exclusively to the symmetrical arrangement of pieces of glass of various colors. As the taste for correct drawing developed, the simple arrangement of glass lost its importance and was finally eclipsed by painting. In the sixteenth and seventeenth centuries, correct delineation in painted windows became the rule, the result being a much higher and more elaborate rendition of historical designs. Since that time, a reaction has, from one extreme to another, taken place. We see, at one time, the ground diversified with a multitude of brilliant colors, variegated by figures, after patterns more or less clearly defined, while, at another, these figures, surrounded by splendid borders or friezes, are obliged to give way to architectural backgrounds and imitations of the antique.
191. The easel for glass painting consists of an oblong wooden frame, whose greatest dimension is its height, its interior border supplied with grooves for the reception of a plate of glass. This frame, placed within a still larger one, may be raised or lowered in grooves at pleasure. The exterior frame has, on both sides of its length, a series of holes, and the interior frame may be thus supported at any given height, by means of pegs inserted into these holes. The easel is usually placed obliquely on a raised form or table, supported in this position by two props at the back, bound together with a cross-bar, hinged at the top and held at a proper distance by movable hooks, permitting it to be closed up at pleasure.
192. The wax for fastening the plates of glass on the easel is similar to modeling wax, and consists of beeswax, 4 parts, Burgundy pitch, 1 part. To the Burgundy pitch it owes its ductility, while it derives its adhesiveness from the greasy matter nearly always contained in the beeswax of commerce.
193. The glazier's work consists: First, in cutting out the various pieces of glass to be stained or painted, and giving these the exact form required by the outlines of the cartoon; second, in encasing the glass in lead when the painting is finished, and forming it into the panels of which the whole picture is composed; third, in arranging it permanently in the arming.