Clay and Ceramic Terms
Glass Terms
Painting and Drawing Terms
Photography Terms
Prints and Original Graphics Terms
Sculpture Terms

Clay and Ceramic Terms

Coil method One of the oldest ways of forming pottery. Long strands of clay are laid on top of each other and joined through blending coil to coil. Coil pieces can be almost any shape or 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 must 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 it 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, 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.

Glass Terms

Ancient glass Generally refers to glass made before 1000 ad.
Anneal To cool glass in a separate kiln at approximately 900° Fahrenheit and slowly cool the object so that any strain created in the glass during the forming process may be released. It takes about 10 hours for the glass to cool to room temperature.
Antique glass A trade term for glass more than 75 years old.
Art glass Glass objects made primarily for their aesthetic, rather than functional, properties.
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 grinding and polishing shop as opposed to a glassworking studio which has a furnace or glory hole (see Hot shop).
Cut glass Grinding stones are worked wet to cut designs into 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 A 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 hydrofluoric acid, HFl, which dissolves glass; dangerous.
Fire polish The reintroduction of an object into the furnace in order to melt the glass smoothly.
Flashing Very thin layer of colored glass fired or vaporized on base glass.
Gather A ball of molten glass on the end of a hollow blow rod, taken from a pot or furnace.
Gilded Metals, such as gold, fired onto glass.
Glory hole A high-temperature chamber used for reshaping glass either on a punty rod or blowpipe.
Glass print (Fr. cliché-verre) A type of print combining photographic and graphic techniques in which a design is scratched on a sheet of glass covered with black paint or albumen; this is then used as a negative and printed on sensitized paper.
Hot shop A glass-working studio containing a furnace and glory hole—especially a glass-blowing studio.
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.
Lead glass Also called flint glass. Lead is the primary flux for the sand.
Leaded glass Stained glass window held in place by lead cames.
Lost wax casting (Fr. cire perdue) A technique in which glass is cast in a mold. 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.” A type of hand-built colored cane.
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.
Punty rod Also pontil. A solid metal rod used to transfer and hold glass when working with a glory hole.
Sandblasting High-pressure air mixed with abrasives 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.

Painting and Drawing Terms
Acrylic A clear plastic used as a vehicle in paints and as a casting material in sculpture. Noted for its quick drying and luminosity.
Charcoal A drawing pencil or crayon made from a black, porous carbonaceous material. Also, charred twigs of willow or vine used by artists because of the various degrees of value achieved when the charcoal is smudged.
Collage A picture built up wholly or partly from pieces of paper, cloth, or other material stuck on to the canvas or other ground.
Conté A proprietary name for synthetic black, red, or brown chalk. Nicolas Conté invented the modern lead pencil.
Egg tempera A water-base paint made with egg yolk binder.
Encaustic Paint made from pigment mixed with melted wax and fixed by heat after application on the surface.
Fresco The Italian term, "fresh." Wall-painting in a medium like watercolor on plaster.
True fresco (buon fresco) One of the most permanent forms of wall decoration
because the pigment is applied while the plaster is still damp.
Glazing The process of applying a transparent layer of oil paint over a solid one so that the color of the first is profoundly modified.
Gold leaf (Also silver leaf) Gold (or silver) beaten into extremely thin sheets; used for gilding.
Impasto The application of thick layers of paint. When paint is so heavily applied that it stands up with the tracks of the brush evident, it is “heavily impasted.”
Naïve art An art form going back centuries through Chagall and Rousseau to peasant art and primitive art. A childlike, primitive depiction of life.
Oil A paint in which a drying oil is the vehicle. Oil color is more easily mixed than acrylic color.
Pastel A combination of pure pigment and binder forming permanent-colored sticks; noted for colors which go from soft to brilliant. When the ground is completely covered with pigment, the work is considered a pastel painting; leaving much of the ground exposed produces a pastel sketch.
Plein air The French term, "open air." Referring to landscapes painted out of doors with the intention of catching the impression of the open air.
Watercolor A painting compound of water-soluble pigment:
Transparent Paint which acts like stain, producing additional colors when one is painted over another; white is produced by the paper’s white surface.
Gouache Opaque watercolors where white is produced by the application of pigment.

Photography Terms
Albumen print A photographic printing process using egg whites in the emulsion.
Alternative processes This term covers at least 35 distinct processes; most have to do with processing the final print for unconventional effect.
Bromoil A highly involved process that can generate one print or, in a transfer variation, many copies. Its chief quality is a delicate painterly/etcherly look. Lithographic ink is applied with a special brush to a gelatinized paper surface that selectively resists or attracts the ink.
Cibachrome A process by which a photographic print is made directly from a color transparency. Noted for rich color, brilliant clarity and unprecedented archival quality for color prints. Also called Ilfochrome.
Cyanotype and Vandyke These methods, and others, made from metals combined with their ferric salts (platinum, palladium, gold, copper, etc.), can produce infinite monochrome variations with capacity to convey special moods.
Daguerreotype An early photographic process (invented in 1839) where the impression made on a light-sensitive silver-coated metal plate is developed by mercury vapor. Each is an original since no duplication process exists.
Dye transfer A method of making color prints or transparencies that gives the maximum control of color, balance, and contrast. One of the most permanent color processes.
Gum bichromate Often called “gum.” An early process in which exquisite colored prints are made by printing on paper coated with layer(s) of sensitized and pigmented gum arabic.
Gumoil A recently discovered process which has the look and feel of some of the ancient processes. In combination with unpigmented gum, etching bleach, and oil pigments, it is possible to build monochrome or polychromatic images.
Orotone An image printed on glass then backed in gold; also called gold-tone or curt-tone. It is often found in ornate, molded, or gilded frames.
Pinhole An old, but currently popular way of taking pictures using a simple box without a lens, but with a tiny hole and a sheet of film pinned inside, opposite the hole. Produces unique perspective and dreamy focus.
Platinum/palladium A print in which the final image is formed in platinum or palladium. Both of these processes are extremely permanent and have delicate rich tones and ranges of greys that are unattainable in silver prints. These processes are enjoying
a revival today with a number of contemporary photographers coating their own paper.
Photogravure An intaglio printing process in which the image has been placed on the plate by photographic means using carbon tissues.
Polaroid transfer It is possible to float off the emulsion layer of a conventional Polaroid print and apply it to a new paper support with interesting effects.
Silver print A generic term referring to all prints made on paper coated with silver salts. Most contemporary black-and-white photographs are silver prints.
Vintage A photograph printed within a very few years of the date when the negative was made. Prints made recently from original negatives that are old are called modern prints.

Prints and Original Graphics Terms
Artist’s proof  One of a small group of prints set aside from the edition for the artist’s use and signed “AP”; printer’s proofs are sometimes also done for the printer’s use, and signed “PP”.
Chop  The impression embossed by the publisher’s, the artist’s, or the printer’s seal on the paper, usually in the lower margin.
Collograph  A print made from a matrix built up with materials such as glue and low-relief items. The inked image is transferred from matrix to paper on an etching press, and is simultaneously embossed. The term derives from “collage,” i. e., the additive process of creating the matrix.
Edition  A set of identical prints that is pulled by, or under the supervision of, the artist, and signed and numbered by the artist.
-- Open edition  An unlimited number of impressions.
-- Limited edition  A known number of multiple-original impressions, usually fewer than 200, that are signed and numbered in pencil by the artist, e.g., “1/10”. (see Original print).
Intaglio  The Italian term, “cut in.” A method of printing in which the image is engraved or etched into a copper or zinc plate, so that the areas to be inked are recessed beneath the surface of the printing plate. After the non-image surface area is wiped clean, damp paper is placed on the plate and run through an etching press, embossiing the paper into the engraved areas and thus transferring the image. The primary intaglio processes are:
-- Aquatint  A tonal process where a porous ground (traditionally, melted particles of powdered resin) allows acid to penetrate to form a dense network of micro dots. Any pure whites are stopped out entirely before etching begins, then the lightest values are etched, then stopped out, and so on, as in line etching. This process is repeated until the darkest tones (deepest recesses in the plate) are reached.
-- Engraving  The image is incised by hand directly into a copper plate with a sharp, chisel-like tool called a “burin”. Originated in the Middle Ages, it is a revivalist technique that requires a long apprenticeship and a very high level of craftsmanship.
-- Drypoint Engraving The image is scribed by the artist directly on a copper plate using a steel needle that produces a burr. This causes the printed line to be slightly fuzzy, adding a richness to the image. Because this wears during printing, editions are usually limited to 25 or fewer prints, unless the plate is electroplated with steel or chrome.
-- Line Etching   In this most common of intaglio techniques, a metal plate is first covered with an acid-resistant ground, then worked with an etching needle. The metal exposed by the needle is “eaten” in an acid bath, creating the recessed image.
-- Mezzotint  A tonal engraving process made by first roughening the surface of the plate thoroughly with tiny, burred dots (using a mezzotint “rocker”), and then rendering the picture by flattening and burnishing selected areas which print as highlights. This revivalist process is laborious, and rarely practiced now because of the relative popularity of photographic methods.
Lithograph  An original print made from a lithographic stone or metal plate on which the image to be printed is created by the artist. The oil-based image area is receptive to oil-based inks, and the non-image area is ink-repellant and water-receptive. The artist, or other printmaker under the artist’s supervision, then impresses the paper on the matrix by using a hand-operated, lithographic press. A separate matrix is required for each color desired.
Iris print  A recently-developed process that uses advanced technology to create a continuous-tone, full-spectrum digital print or reproduction. Using a special, commercial printer, water-based, four-color-process inks are applied to the paper from tiny jets one-tenth the diameter of a human hair. Archival papers may be used. Often referred to as a Giclée.
Matrix The object—plate, block, or stone--from which inked impressions are made for original prints.
Monoprint  One of a series of original prints in which each impression has some differences of imagery, color, design, texture, etc., combined with a repeated part of the image.
Monotype  A one-of-a-kind, original print made by painting on an impervious plate of metal or Plexiglas, and then printing on paper. The pressure of printing creates distinct textures and effects not possible when painting directly on paper.
Original print An impression printed from a matrix or matrices created by the artist expressly for the purpose of making multiple originals. The resultant print is of considerably greater intrinsic worth than a commercial reproduction of a unique original, which is photo-mechanically printed in large numbers on an offset press.
Photogravure  A technically difficult, lens-based, intaglio process invented in 1879 for fine printing, and recently revived by contemporary artists. Using a gelatin photo-emulsion, a film positive of a photographic image is exposed onto a copper plate, which is then etched, and printed in the intaglio method. A “direct gravure” utilizes the same technical process, only with a hand-drawn image instead of a lens-based one.
Photo-process print An original print of any kind in which the artist’s image is transferred to a matrix by using photographic means (photo-emulsions, negative or positive films, exposure units, etc.). May be referred to as a photo-etching, photo-lithograph, photo-relief, photo-screen print, etc.
Relief print An original print transferred onto paper from a relief block that has been carved so that the image is on the surface, and the non-image area is subtracted. Ink is rolled onto the surface, and usually, a separate block is required for each color. A hand “baren” or a press is used to impress the image. Primary types of relief prints:
-- Woodcut An impression on paper printed from a wooden plank or plywood that has been carved as a relief image.
-- Wood “engraving” An antique relief technique that utilizes an end-grain block and very fine lines of both positive and negative values.
-- Linocut  A relief print impressed from a block of linoleum into which an image has been carved.
Serigraph/silk screen print  A form of printmaking utilizing stencils attached to porous screens through which stiff ink is squeegeed onto the paper below; one screen per color. Like other multiple originals, they are most often issued in signed and numbered editions.

Sculpture Terms
Armature A metal skeleton, usually of flexible lead piping, used to support clay or wax in the making of a piece of sculpture.
Lost wax process A method of casting metal sculpture requiring a wax version of the original model. The wax form is encased in a heat-resistant molding material. Baking the mold causes the wax to melt and run out, leaving a cavity in its place. The cavity is filled with molten metal which solidifies to become the sculpture when the mold has been broken open. Also a method used in casting glass sculpture.
Patina The surface of metal sculpture that results from natural oxidation or the careful application of heat, chemicals, and polishing agents.
Surmoulage Fraudulent practice of taking an unauthorized casting from a bronze sculpture rather than from artist’s original.

Prints and Original Graphics Terms written by Mark L. Smith, Flatbed Press, Austin, Texas. Clay and Ceramics, Glass, Painting and Drawing, Photography, and Sculpture terms reprinted with permission of Wingspread Guides of New Mexico, Inc., www.collectorsguide.com