Introduction
Types
Opalescent glass
The term "opalescent glass" is commonly used to describe glass where more than one color is present, being fused during the manufacture, as against flashed glass in which two colors may be laminated, or silver stained glass where a solution of silver nitrate is superficially applied, turning red glass to orange and blue glass to green. Some opalescent glass was used by several stained glass studios in England from the 1860s and 1870s onwards, notably Heaton, Butler and Bayne. Its use became increasingly common. Opalescent glass is the basis for the range of glasses created by Tiffany.
Favrile glass
Main article: Favrile glass
Tiffany patented Favrile glass in 1892. Favrile glass often has a distinctive characteristic that is common in some glass from Classical antiquity: it possesses a superficial iridescence. This iridescence causes the surface to shimmer, but also causes a degree of opacity. This iridescent effect of the glass was obtained by mixing different colors of glass together while hot.
According to Tiffany:
"Favrile glass is distinguished by brilliant or deeply toned colors, usually iridescent like the wings of certain American butterflies, the necks of pigeons and peacocks, the wing covers of various beetles."
Streamer glass
Streamer glass refers to a sheet of glass with a pattern of glass strings affixed to its surface. Tiffany made use of such textured glass to represent, for example, twigs, branches and grass.
Streamers are prepared from very hot molten glass, gathered at the end of a punty (pontil) that is rapidly swung back and forth and stretched into long, thin strings that rapidly cool and harden. These hand-stretched streamers are pressed on the molten surface of sheet glass during the rolling process, and become permanently fused.
Fracture glass
Fracture glass refers to a sheet of glass with a pattern of irregularly shaped, thin glass wafers affixed to its surface. Tiffany made use of such textured glass to represent, for example, foliage seen from a distance.
The irregular glass wafers, called fractures, are prepared from very hot, colored molten glass, gathered at the end of a blowpipe. A large bubble is forcefully blown until the walls of the bubble rapidly stretch, cool and harden. The resulting glass bubble has paper-thin walls and is immediately shattered into shards. These hand blown shards are pressed on the surface of the molten glass sheet during the rolling process, to which they become permanently fused.
Fracture-streamer glass
Fracture-streamer glass refers to a sheet of glass with a pattern of glass strings, and irregularly shaped, thin glass wafers, affixed to its surface. Tiffany made use of such textured glass to represent, for example, twigs, branches and grass, and distant foliage.
The process is as above except that both streamers and fractures are applied to sheet glass during the rolling process.
Ring mottle glass
Ring mottle glass refers to sheet glass with a pronounced mottle created by localized, heat-treated opacification and crystal-growth dynamics. Ring mottle glass was invented by Tiffany in the early 20th century. Tiffany's distinctive style exploited glass containing a variety of motifs such as those found in ring mottle glass, and he relied minimally on painted details.
When Tiffany Studio closed in 1928, the secret formula for making ring mottle glass was forgotten and lost. Ring mottle glass was re-discovered in the late sixties by Eric Lovell of Uroboros Glass. Traditionally used for organic details on leaves and other natural elements, ring mottles also find a place in contemporary work when abstract patterns are desired.
Ripple glass
Ripple glass refers to textured glass with marked surface waves. Tiffany made use of such textured glass to represent, for example, water or leaf veins.
The texture is created during the glass sheet-forming process. A sheet is formed from molten glass with a roller that spins on itself while travelling forward. Normally the roller spins at the same speed as its own forward motion, much like a steam roller flattening tarmac, and the resulting sheet has a smooth surface. In the manufacture of rippled glass, the roller spins faster than its own forward motion. The rippled effect is retained as the glass cools.
Drapery glass
Drapery glass refers to a sheet of heavily folded glass that suggests fabric folds. Tiffany made adundant use of drapery glass in ecclesiastical stained glass windows to add a 3-dimensional effect to flowing robes and angel wings, and to imitate the natural coarseness of magnolia petals.
The making of drapery glass requires skill and experience. A small diameter hand-held roller is manipulated forcefully over a sheet of molten glass to produce heavy ripples, while folding and creasing the entire sheet. The ripples become rigid and permanent as the glass cools. Each sheet produced from this artisanal process is unique.
Techniques for cutting Tiffany glass
In order to cut streamer, fracture or ripple glass, the sheet may be scored on the side without streamers, fractures or ripples with a carbide glass cutter, and broken at the score line with breaker-grozier pliers.
In order to cut drapery glass, the sheet may be placed on styrofoam, scored with a carbide glass cutter, and broken at the score line with breaker-grozier pliers, but a bandsaw or ringsaw are the preferred.
