Fluting Grooves - cut into the clay in parallel lines running in any direction.
Flux - means flow, fluxes are materials that help glazes flow. They do this by lowering the temperatures at which other minerals would naturally melt.
- bottom of a pottery or ceramic piece.
Forming - the making of a piece of clay into a piece of pottery.
Frosted - if there is a hole, or slight air intake during the firing of a piece of pottery, one side may end up under fired, which will make part of the pottery look lighter in appearance than the rest of the pot.
Frit - by heating two or more raw materials together, this is a manufactured glaze or clay that is melted together to form a glass that is then shattered, usually by pouring into cold water. The shattered pieces are then ground into powder prior to being added to a glaze recipe.
Fuse - to melt together.
Gadroon Edge - an in-the-mold decoration, usually found on the edge or rim of a piece of pottery that resembles a braided rope.
Galena - lead ore, impure, used to make lead glazes. In the 10th to the 17th centuries Galena was dusted on newly thrown wet pottery. This fused the upper layer of clay during the firing into a glaze.
Gilding - the application of precious metals such as gold or platinum to pottery.
Glaze - a layer of ceramic or glass that is a mix of dolomite, frit, flint, feldspar, sodium borate, clay and whiting. It can be applied by dusting, dipping or brushing a thin slurry on the surface of a pottery or ceramic piece, used to seal the piece, decorate it, or both.
Gloss - a glaze which has a smooth, shiny surface.
Glost Kiln - is used for firing glazed pieces, decal-decorated pieces, the firing is not as hot as the bisque firing nor as long.
Green Glaze - produced when small amounts of iron is added to a glaze.
Greenware - unfired pottery.
Grog - clay that has been fired and then ground into granules of more or less fineness. It is considered a filler and added to clay bodies for several reasons, it helps open a tight or dense body and promotes even drying, which reduces warping and cracking, and reduces overall shrinkage. Grog also adds tooth and texture to a clay body aiding in the ability of the body to maintain its form during construction.
Hard Spot - a darkier looking spot on greenware that when fired will not hold paint.
High Fire - firing at about 2305 F (1263 C) or cone 8. Typical stoneware and porcelain.
Hispano-Moresque Ware - during the Moorish occupation of Spain, this lusterware pottery was made. Between the 8th and 15th centuries the Moors, Spaniards, Christian and the Islamic were responsible for this pottery. Over time the luster became coppery in color.
Hot Spot - section of kiln that fires hotter than rest of kiln.
Humper - a distorted plate, where the flat part has risen up in an unacceptable fashion. Usually found on pressed plates and or plates that are glazed only on the top and sides.
Hump Mold - the process of laying a slab of clay over a shape, the hump, or slapping, paddling or pounding an amount of clay over such a form.
Ilmenite - the ore of titanium and iron. Granular ilmenite is used to produce a speckled effect in clay bodies and glazes. In small amounts it can promote or “seed” the growth of crystals in glazes especially those containing rutile.
Impressed Design - stamped into the leather-hard clay with a tool or die.
Impressed Mark - stamped into the leather-hard clay with a tool or die.
Incised Design - pattern cut into the clay with a sharp tool.
Incised Mark - maker's name, monogram or mark cut into the clay with a pointed tool.
Inglaze - application of ceramic colors onto unfired glazes. The colors will sink into the glaze, and stain it. These colors are pure oxides, strongly colored glazes or stains that have been prepared for this.
Inlay - a type of decoration where the surface of cheese hard clay is scored and filled with a thick colored slip. After the slip dries the excess is scraped off to show the clean lines.
Iron Oxide - one of the pottery workers favorite colorants, when combined with the right glaze and firing, iron oxide can produce greens, browns, blacks, yellows, oranges or subtle blues and grays. Most of the best color responses for Iron in a glaze need a reduction firing. Iron is also a useful colorant in clay bodies and is best introduced by adding high iron clays to the clay recipe.
Jiggering - process for making plates and other fairly flat items. The clay is placed on a form that represents the top of the piece, pressed down and spun. A template representing the outline of the underside of the piece is placed against the clay and finishes the shaping.
Junior Cones - small cones are commonly used in a kiln-sitter. The tapered shape allows some flexibility to adjust the shut off point by placing the thinner or thicker portion of the cone under the sensing rod.
Jun - a pale blue opalescent stoneware glaze. The glaze needs to be applied in a thick manner, otherwise the body will show through and it will seem almost transparent. The origin of this term is from a town in northern China in the 11th century.
Jutland Ware - the origin of this pottery is that of Neolithic times, nearing the end of the Stone Age. It was perfected early on and continued to be made until the mid-20th century. This was unglazed, peat-fired pottery.
Kaki - Japanese name for the rust color that appears on the surface of stoneware glazes. This occurs when iron oxide crystals spread.
Kaolin - a china clay in its purest form. Primary clay.
Kaolinization - the natural formation of kaolin from the decomposition of feldspar.
Keuper Marl - this is a high quality mudstone found during the Triassic Period, a time characterized by the appearance of dinosaurs and a time of high volcanic activity. It began as a desert dust that can be reconstituted as clay. It is high in clay content, iron, and lime. Brown and gray when raw but brown-burning.
Kickwheel - a piece of equipment that a pottery worker uses to spin a mound of moist clay while they use their hands to shape a pot. It is put in motion by kicking a round flat weighted disc that the pottery worker rests a foot on, thus spinning the disc on the table where he is working the clay.
Kidney - a kidney shaped tool which can be used for finishing thrown pots as well as smoothing and pressing clay in a mold. For use in finishing thrown pots, it is made of flexible steel. When used for smoothing and pressing clay, it is made of stiff rubber.
Kiln - an insulated box, which is heated to fire pottery in. They can be either, cross draft, down draft, or up draft. The draught refers to the direction the combustion gasses have to travel from input to exit flues. Since no combustion takes place in an electric kiln there are no input or exit flues and they are genuinely heated boxes. The fuels used to heat a kiln are gas, oil, wood, coal (now almost obsolete) and electricity. Each fuel source used to fire a kiln offers different possible outcomes for the pottery fired in them. The maximum operating temperature for most pottery kilns is about 2372 F (1300 C) although many wood fired kilns may be fired up to 2462oF (1350 C).
Kiln Sitter - two stationary prongs sticking out from wall of kiln about 1/2 inch long and 3/16 inch apart with a rod in center, called a sensing rod, that raises and lowers. A cone for the temperature that is needed is placed across the stationary prongs and center rod lowered down onto cone. When proper temperature is reach the cone will sag and lower center rod, shutting off the kiln. There is also a time limiter knob that will shut the kiln off incase the kiln sitter malfunctions. See also cones, cone numbers and high fire and lo fire.
Kiln Vent - a hood above a kiln, or ducting on the bottom of a kiln that has a fan that draws the firing fumes from inside the kiln to the outside.
Kiln Wash - a refractory mixture, usually kaolin or flint, which is painted on kiln shelves and staggers to prevent glaze from adhering.
Kneading - clay preparation, where a lump of clay is rolled in upon itself, while stretching, pulling and pounding to get out the air bubbles.
Kochi - this is Japanese raku pottery. A hard-fired biscuit is used.
Kwaart - to give a higher gloss and depth to color, this technique was used by the Delft pottery workers to imitate Chinese blue-and-white porcelain. To get this effect they used a clear tansparent glaze over a white opaque glaze.
Large Cones - pyrometric cones used as a witness cone on the kiln shelf to visually monitor the progress of the firing and heat work throughout the kiln. Large cones need to be supported by a cone plaque, a clay pat, or a wire cone holder. Cones are mounted at an 8 degree angle so 2" of the cone is exposed above the pat. A 1 3/4" mounting height can also be used to match self-supporting cones. Uniform mounting height and angle are very important.
Lead Glaze - long before chronic lead poisoning became a public health issue lead was a popular constituent of ceramic glazes and contained lead oxide and created a very shiny finish. Some vibrant colors, particularly red and green, can only be achieved with lead glazes.
Leather Hard - this is a stage midway between wet and dry clay. The clay will be stiff enough to support it’s own weight, but pliable enough to be bent and worked with.
Lining - a decorative process where a thin line of gold, silver or a color is applied to the pottery by hand.
Low Fire - firing a kiln above 1300 F (704 C), but more typically from 1641 F (894 C) and up to 1940 F (1060 C), or cone 010 to cone 04.
Luster - soft reflective, brilliant and radiant color.
Lute - to join two pottery surfaces together with slip.
|Sometimes we have to replace "what if's" with some good old fashioned "so what's."