Acid etched

• Glass (usually flashed, see definition below) that has had a layer eaten away by hydrofluoric acid.  This leaves a matte finish and usually a lighter color.

Annealed

• Glass that has been cooled slowly, resulting in a soft glass that is easy to cut.  Opposite of “tempered.”

Antique

• Glass made by the “antique” method, namely by an artisan blowing a glass bubble that is formed into a cylinder, that is cooled, cut open, and then flattened in a reheat oven.  This glass is characterized by variations in thickness that give the glass a gradient in color across each sheet. It usually also has some small air bubbles and/or variations in the refractive index that produce slight prismatic effects.

Architectural

• Glass designed to become part of a building’s structure.  This term is used when the architect specifies the glass as part of the architectural design.

Art

• A generic category that covers all artistic uses of glass as contrasted with functional use. Typical art glass types are stained glass, carved glass, fused glass, lamp-worked glass.

Artique

• An imitation of antique glass made by Spectrum Glass Company.  The fine lines from a change of density in antique glass are molded into the surface of this glass giving a similar effect  in a machine-rolled glass at lower cost than true antique blown glass.

Backing 

• A thin piece of glass used to hold together broken fragments of old glass by adhering to them (usually with silicone or epoxy).

Back-lighting

• A method of using artificial light to illuminate stained glass not illuminated by sunlight.
  Baroque An artistic style of stained glass characterized by the use of curved lines and extravagant ornamentation.

Bent Glass

• that has been bent by heating and , usually, forming it over a curved mold.

Beveled Glass

• that has the edge cut off at an angle. This bends the light and produces a prismatic effect. The bevel is made by grinding off the edge of flat glass. Straight-edged bevels can be made by multiple machine grinding steps while curved edge bevels must be hand-made.

Blown Glass

• made from blowing a glass bubble on the end of a hollow tube. An artisan may then shape it by spinning, rolling and pinching with iron tools to make a vase, bottle, glass or other object. Alternatively, the bubble may be placed into a hollow mold and further blown until it expands into all of the details of the mold.

Border

• A band of glass that surrounds the main work in a window. It’s purpose is to frame but also to allow removal of a non-essential area to adjust the fit of the stained glass to the window. It is often made of strips, geometric, or plant shapes.

Bottle Sheet glass

• that is cut from the four sides of a glass bottle that was blown into a square mold. It has been replaced by the cylinder-blowing method described under “Antique.”

Carved Glass

• with the appearance of a three-dimensional sculpture imprisoned within the glass. This is achieved by etching the glass to varying depths.

Cast Glass

• made by pouring molten glass into a mold.

Cathedral Transparent

• glass of uniform thickness made by squeezing molten glass between rollers. The color is uniform across the piece of glass (no color gradient). Usually one roller is smooth and the other textured, which gives texture to the glass. (See “Hammered” below for one of the more popular textures).

Copper-foiled

• Copper-foil is a method for making 2 or 3-dimensional objects from small pieces of colored glass. Very thin strips of copper foil are wrapped around the edges of each piece of glass. The pieces are positioned into the desired shape or design and then soldered together. The copper foil is completely hidden underneath the solder, which is usually blackened by application of a patina-forming chemical. Stained glass lamps of all shapes are made by this method.

Crackle Glass

• made by dipping a molten cylinder into water. The exterior of the cylinder cracks but the molten interior holds it together. The cylinder is sliced down the side and flattened. There are now imitation crackle textures rolled into glass.

Crown Glass

• that is rotated as it is blown, thereby creating a disk shape with a knob, or crown, in the center. Same as Roundel.

Cut Sculptural glass (three-dimensional, like a vase or goblet) that has designs cut into the glass with a copper wheel.

Curious Glass

• that did not meet the manufacturer’s specifications (in other words, “rejects”). Mostly this glass is very unusual, unpredictable, sometimes beautiful and sometimes ugly.

Cylinder

• Most common type of blown glass. The glass bubble is blown into a cylinder, the ends cut off, the cylinder split along its length, and then unrolled into a flat sheet.

Dalle de Verre “Slab of glass” (translation from the French)

• is a cast chunk of glass approximately 1″ x 10″ x 8″ that is used to make “faceted” glass windows (see “Faceted”).

Dichroic Glass

• that has a thin metal film vaporized onto its surface. The glass transmits one color and reflects a different color. Each manufacturer offers about a dozen different color combinations.

Double-glazed

• Two layers of glass with a seal around the edges. The edge strip usually contains a desiccant to prevent moisture accumulation between the glass surfaces.

Drapery Glass

• with varying thickness and irregular ripples. It is made by pushing a hot sheet of glass across a tabletop into folds resembling fabric drapery.

Enameled Glass

• design made by melting enamels on the surface of the glass.

Encapsulated Glass

• which has been sealed inside a “sandwich” of two sheets of clear glass.

Etched Glass

• with some of the surface removed by either a chemical or sandblast process. The result is that the glass is slightly thinner in the etched region and has a diffused reflective surface, thereby appearing whiter in color.

Faceted Slab

• glass that has been chipped on the edges to cause thin flakes of glass to break off the flat surfaces. Pieces of this type of glass are set into an epoxy-concrete mixture to produce large architectural window-walls. The fractured edges (“facets”) cause the light to bend and refract (break into a rainbow of colors).

Favrile

• Type of glass produced by Louis Comfort Tiffany that is opalescent with a coppery metallic coating. Note: Starting in 1892, Tiffany called his glassware “Fabrile”, supposedly, derived from the old English, meaning “hand-made”. “Fabrile” evolved into “Favrile”, which he trademarked on November 13, 1894. He used this word to apply to all of his glass, enamel, and pottery.)
  Fired Heated to a critical temperature in a kiln. The temperature depends on the glass and the desired effect. Painting becomes part of the glass about 1200 degrees F. Glass will slump or fuse (see definitions) at higher temperatures.

Flashed

• The glass has a thin coating of a second color of glass processed onto the base glass. For example, most antique reds are made of clear glass with a very thin layer of intense red glass.

Flat Glass

• art that has minimal thickness. The glass has NOT been worked into a three dimensional shape by being bent or fused or otherwise assembled or distorted.

Float Glass

• that is made by floating molten glass on a bed of mercury. This makes an extremely smooth and flat surface.

Fluted Glass

• that has evenly spaced flutes running parallel to each other.

Fused

• Two or more pieces of glass that have been melted together to form one piece.

Globs

• Non-uniform round or oval smooth “puddles” of glass with one flat rough side formed by dripping glass onto a table.

Glue-chip Glass

• that is covered with an animal glue and then dried in an oven. The glue shrinks and pulls chips out of the glass surface leaving a delicate, random, feathery, fern-like texture. This process can be repeated for a denser “double chip” appearance.

Grisaille

• Black or brown fusible paint used for shading on glass. Grisaille glass is glass that has been painted and fired.

Hammered Glass

• textured by indentations which resemble a surface that has been beaten with a ball-peen hammer.

Hot Glass

• that has been worked by a hot process such as fusing, firing, blowing or lamp-working.
  Impact-resistant A type of engineered laminated glass that offers considerable resistance to impact from natural or man-made missiles impacting the glass. Bullet-proof and hurricane-proof glass.
  Inlaid A type of laminated glass where the art glass is laminated to a plate glass substrate by epoxy.
  Insulating Two pieces of glass that have been sealed together at the edges. The edge strip usually contains a desiccant to prevent moisture on the interior glass surfaces. The space between the glasses may be filled with argon gas.

Iridescent

• Glass on which a very thin coating of metal has been applied. This thin coating reflects light from the upper and lower surfaces of the metal. These reflected light waves interfere with each other and produce a rainbow effect similar to that produced by a thin film of oil on water.