Stained-glass.
Glass painted on the surface with various mineral pigments, which are afterward fused and fixed by the application of heat.
The glass should be colorless, uniform, and difficult of fusion; crown glass, made with but little alkali, being preferred.
The design on paper is applied to the back of the glass, and the outlines traced through with a fine pencil in dark colors, after which the proper pigments to produce, when burnt, the various colors, are applied to the face of the glass, previously coated with gum-water.
Where lights are required, the colors are partially removed by a quill pen without a split.
Where two colors adjoin which are apt to run into each other during fusion, one is applied on the back of the glass.
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Staging. |
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Roof-staging. |
The plates are burnt in a close muffle of fire-clay, closed by folding doors of iron having peep-holes, through which the progress of the work may be viewed, and test-strips, containing the several pigments, withdrawn.
The plates are laid on a layer of dry sifted lime, sometimes in several layers, with lime interposed between each.
The fire is raised very gradually, to prevent cracking the glass, and a full heat is maintained for three or four hours, after which it is gradually allowed to die out to anneal the glass.
See glass-staining, page 983; glass-color-ing, page 977.
