Glossary of Glass
Ancient Glass Generally refers to glass made before the Venetian era of glass making.
Anneal To cool glass by reintroducing a completed object into an auxiliary part of the glass furnace and slowly cooling the object so that any strain created in the glass during the forming process may be released. The critical area for cooling is 1000-800 degrees.
Antique glass A trade term for glass more than 25 years old.
Blown glass The shaping of glass by blowing air through a hollow rod into the center of a molten glass gather.
Cane Any string or rod of glass.
Cold shop A glassworking studio that does not have furnace or glory hole (see Hot shop).
Cut glass Grinding stones that are worked wet to cut designs onto glass.
Direct carving Glass chunks may be carved, ground, chiseled or otherwise shaped like other sculpture materials.
Enameled glass Opaque glass colors melted onto glass surface. The colors are actually glass powders.
Engraving Design cut or scratched on glass with diamond point, stone, metal or copper wheel. Usually more complex and flexible than cut glass work.
Etching Glass may be etched by hydroflouric acid, HF1, which likes silica. Dangerous.
Fire polish The reintroduction of an object into the furnace in order to smooth an irregularity. A technique used to retain a shiny surface to glass after it has been ground on a grinder or sandblasted.
Flashing Very thin layer of colored glass fired or vaporized on base glass.
Gather A ball of molten glass taken from a pot or furnace on the end of a hollow blow rod.
Gilded Metals, such as gold, fired onto glass.
Glory Hole A high-temperature chamber used for reshaping glass either on a punty rod or blow pipe.
Hot shop A glassworking studio containing a furnace and glory hole--especially a glass blowing studio.
Incalmo Joining two or more blown sections while hot.
Iridescence Thin laminated flakes of glass showing decomposition with age. Also artificial, as done by Tiffany.
Iridized glass Glass whose surface is chemically treated to have a rainbow or iridescent appearance.
Kiln Insulated chamber for heating and cooling glass or ceramics.
Kiln-formed Glass that is altered, fused, shaped,or textured by the heat of a kiln.
Latticinio Threads of white or colored glass within clear glass, sometimes lace-like in pattern.
Lamp work Any glass-working technique done with the direct flame of a torch; work with pre-formed glass rods and tubes.
Leaded glass Stained glass window held in place by lead cames.
Lost wax casting The object is modeled in wax and cased in a ceramic or plaster mold. The mold is heated and the wax flows out; powdered or molten glass is poured into the mold.
Millefiori The Italian term, "thousand flowers," used to describe mosaic glass objects.
Mosaic glass Vessels or objects are built up of preformed elements of glass placed around or in a mold and slowly heated until the glasses fuse together.
Overlay Blowing a bubble with color on the inside, the bottom is attached to a solid core and then the bubble is turned inside out, leaving a thin color "flash" on the outside.
Punty rod A solid metal rod used to transfer and hold glass when working with a glory hole.
Sandblasting High-pressure air mixed with sand applied to the surface of glass to carve texture.
Slump A technique used to form glass using a mold, heat and gravity.
Thermal Shock Glass breakage caused by rapid or uneven heating or cooling.
Glossary of Ceramics and Clay
Coil method One of the oldest ways of forming pottery. Long strands of clay which are laid on top of each other and joined through blending coil to coil. Coil pieces can be almost any shape and any size.
Crackle glaze Minute decorative cracks in the glaze that are often accentuated by rubbed-in coloring material.
Crazing The fine network of small cracks that occurs on glazes. The Japanese encourage crazing and will stain cracks with concentrated tea.
Earthenware A low-fire clay. Porous and not waterproof. To be functional, it needs to be glazed.
Firing Clay is hardened by heating it to a high temperature, fusing the clay particles. Primitive pottery is usually fired on the ground or in pits
with whatever flammable material is available. Kilns allow a more efficient use of materials and more control over the atmosphere during a firing. The
two basic atmospheres, oxidation and reduction, affect the color of the final piece. Glaze A coating of material applied to ceramics before firing that forms a glass-like surface.
Glazes can be colored, opaque, translucent or matte.
Kiln The furnace in which ceramics are fired. Kilns can be electric, natural gas, wood, coal, fuel oil or propane. Materials used to heat the kiln
can affect the work: wood ash can build up on the surfaces of a piece and form a glaze at high temperatures. Some potters introduce chemicals into the
kiln to influence the effects of the firing. Famed ceramist Beatrice Wood achieved a lustre effect by throwing moth balls into the kiln.
Oxidation (Compare to Reduction) A firing atmosphere with ample oxygen. An electric kiln always gives an oxidizing fire. In a wood or gas firing, the
mixture of fuel and air is perfectly adjusted to give a clean burn. Acoma whiteware is fired in oxidation.
Oxides Metal oxides can be mixed with water and applied to the surface of clay. By varying the amount of material applied and rubbed off, the potter
can achieve effects similar to stained wood. The most common stain is iron oxide (rust).
Pinch Pots Starting with a ball of clay the potter opens a hole into the ball and forms a bowl shape through a combination of stroking and pinching
the clay. Many coil-built pieces are constructed on top of a pinched bottom.
Porcelain True porcelain was being made in China and Korea around 960 AD. Porcelain is a combination of kaolin (a pure, white, primary clay), silica
and feldspar. A unique aspect of porcelain is that it can be worked as clay, but when fired properly reaches a state similar to glass. Primary qualities
of porcelain are translucency and whiteness. In the 17th Century, English potters invented Bone China to compete with the porcelain being imported into Europe.
Raku Pottery is fired normally but removed when it is red hot and the glaze is molten. It is then usually placed in a bed of combustible materials and covered,
creating intense reduction resulting in irregular surfaces and colors.
Reduction (Compare to Oxidation) A firing atmosphere with inadequate oxygen and large amounts of carbon (smoke or unburned fuel). What would have been copper
oxide in an oxidation atmosphere will be pure copper in reduction. Reduction allowed the Chinese to develop the sangue de beouf red glazes and gives Raku its
metallic finishes. In Indian pottery, Maria's black pieces are the result of heavy reduction; the same piece in oxidation would be a terra cotta color.
Slab Built Clay slabs are cut to shape and joined together using scoring and wet clay called slip. Slabs can be draped over or into forms, rolled around
cylinders or built-up into geometric forms. Large forms are difficult because of stresses on the seams and because the slab naturally sags. Some potters
get around this by working fibers into the clay body. The fibers burn out during the firing, leaving a network of tiny holes.
Slip A fine, liquid form of clay applied to the surface of a vessel prior to firing. Slip fills in pores and gives uniform color.
Stoneware A high-fire clay. Stoneware is waterproof even without glaze; the resulting ware is sturdier than earthenware.
Terra cotta A brownish-orange earthenware clay body commonly used for ceramic sculpture.
Wheel thrown The term throw comes from Old English meaning spin. A piece of clay is placed on a potter's wheel head which spins. The clay is shaped by
compression while it is in motion. Often the potter will use several thrown shapes together to form one piece (a teapot can be constructed from three or four thrown forms).
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