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GLOSSARY 
For the infiormation for entries in this glossary, 
the author heavily relied on Freestone and 
Gaimster, eds., Pottery in the Making, 
pp. 214 216. 
Applied decoration: Decoration created by 
   adding hand-fornied or molded clay cotrpo- 
   nents to the surface of a pot. 
Biscuit firing: The firing used to harden a clay 
   body that has not yet received its glaze nor, 
   in somse cases, colored decoration. 
China clay: See Kaolin. 
China stone: Also known as porcelain stone. 
   A rock composed of quartz and alkali 
   teldspars that is ground for use as a 
   porcelain flux. 
Clay: A fine-grained, natural material that, 
    when wet, is characterized by its plasticity 
    (the ability of the clay to be manipulated 
    and shaped without cracking). Additives are 
    used to alter the properties of the clay. 
 Cobalt oxide: A pigment used under, over, or 
    suspended in ceramic glaze to achieve a 
    color ranging friom pale to deep blue. 
 Combing: On slipware a type of decoration 
    created by dragging a comblike tool across 
    a patterned slip (see below) surface. 
 Copper oxide: Used since ancient times as a 
    ceramic and glass colorant. Copper oxide 
    fires to green when fired in oxidation (see 
    below) with a lead or tin glaze. 
 Delftware: Name, after prolific Dutch potting 
    center at Delft, Holland, for English tin- 
    glazed earthenware (see below). Same name, 
    sometimes with an uppercase D, also used 
    for Dutch versions of the pottery. 
 Earthenware: A ceramic body usually formed 
    o lbuff to red clay that is not fully vitrified 
    (see below) when fired and thus remains 
    relatively porous. Earthenware clay can be 
    dug and used with little refinement in some 
    cases or, for more elegant wares, can be 
    highly purified. 
 Enamel: A type of decorative pigment conm 
    posed of a metallic oxide and a glass flux 
    that is painted over a fired glaze and con- 
    pleted in a low-temperature firing. 
 Fabric: The combination of clay and inclusions 
     that makes the ceramic. 
 Faience: In the context of this publication, 
     the French term fcr tin-glazed earthenware, 
     a translation of the name for the Italian 
     potting center of Faenze. 
  Firing: The heating to a high temperature of 
     clay bodies in order to render them hard, 
     durable, and no longer soluble in water. 
Firing temperature: The highest temperature 
   attained during tise firing of a clay body, 
   glaze, or, in some cases, decoration. 
Flint: A very fine-grained and popular source 
   of silica, often foiund as large nodules its 
   chalk and limestone deposits. 
Flux: A substance added to a clay or glaze to 
   lower its melting temperature. 
Glaze: A thin, silica-rich, often transparent 
   layer on tse surface of a ceramic body 
   (see Salt glaze, Lead glaze, Tin glaze). 
Inclusions: Large-grained particles in a clay 
   body, sonmetimes indicating that tlse clay 
   was little refined and soimetimes added to 
   reduce shrinkage or firing temperat tire. 
Iron oxide: The most common oxide aflecting 
    the fired color of ceraissic clay, a strong col- 
    orant that results in earth tones when fired 
    under a lead or salt glaze in oxidation (see 
    below). Also used as a vety effective flux. 
 Kaolin: Another name for china clay, a 
    material that is highly refractory and rich 
    in the iniseral kaolinite. Kaolin deposits, 
    comparatively rare and differing in cluality, 
    are known from Asia, FEurope, England, and 
    North America. These white-firing clays are 
    low in iron oxides and fluxes (see above) 
    and tend to need other materials in the mix 
    to increase their plasticity (see below). 
 Kickwheel: A potter's wheel (see below) that 
    has a large, weighted circular base that is 
    turned by ldcking with the foot. 
 Kiln: The structure within which pottery is 
    fired. At the bottom is the firebox, its which 
    the fire is set and frois which one or more 
    flues carry the hear into the firing chamber, 
    where the pots are stacked. A vent for the 
    loss of waste gases is typically at the top of 
    an updraft kiln. 
 Lathe-turned: See Turning. 
 Lead glaze: A glaze that melts at a compara- 
    tively low temperature (around 840" C.) 
    and for which the main flux is lead oxide. 
    Known from ancient times, lead glaze 
    usually was applied as a powder or in 
    suspension in water and, as it cannot 
    tolerate the high temperatures needed 
    to complete stoneware or porcelain, was 
    used on earthenware bodies. 
 Maiolica: The Italian term for tin-glazed earth- 
     enware. 
 Manganese oxide: A relatively conmuson metal 
     oxide that fires in oxidation (see below) to 
     black, brown, or purple. 
  Modeling: The shaping of a piece of clay with 
     tiue fingers or with any of several types of 
     tools. 
Overglaze decoration: D)ecoration, sometimes 
   in colors that cannot withstand glaze-firing 
   temperatures, that is applied to the surface 
   of the finished glaze beibre being completed 
   in a comparatively low-t emperature firing. 
   Alternatively some color ornament and gild- 
   ing can be applied over the glaze and 
   adhered with an adhesive rather than 
   through heating. 
Oxidation firing: Firing in a kiln atmosphere 
   where there is excess oxygen, so that iron 
   oxides tend to form red hematite rather 
   than black magnetite and carl)on is burnt 
   out of the clay body. Tlpically produces red- 
   dish pots in low-temrperature earthenware 
   firings. 
Press molding: Forming soft clay by pressing it 
    in or over a mold. Press-molding clays must 
    be somewhat plastic but must shrink or 
    warp comparatively little when drying. 
 Porcelain: A highly vitrified (see below), usually 
    white ceramic that is translucent when 
    thinly potted and can ring when struck. 
 Porcelain stone: See China stone. 
 Potter's wheel: A rapidly rotating device com- 
    posed of a circular, fiat table on a rotatable 
    axis, enabling the potter to use centriltigal 
    force to shape pottery. (See Kickwheel.) 
 Reduction firing: Firing in a kiln where there 
    is a shortage of oxygen. Metallic oxides 
    produce diflerent colors in reduction firing 
    than they do in oxidation firing. In reduc- 
    tion firing, for example, copper oxide pro- 
    duces red rather than green. 
 Saggar: A protective ceramic container, typi- 
    cally of fireclay, used in the kiln to protect 
    glazed or other pottery from damage from 
    fire, gases, or contact with other pots dur- 
    ing firing. 
 Salt glaze: A glaze produced when salt is 
    shoveled into a heated kiln, vaporizes, and 
    creates a chemical reaction with a ceramic 
    body. The high temperature needed for salt 
    glazing makes it suitable for application to 
    stoneware bodies. 
 Sgraffito decoration: A type of slipware orna- 
     ment for which designs or inscriptions are 
     cut through slip (see below) to reveal the 
     body color below. 
 Slip: A syrupy mixture of fine-grained clay and 
     water that sometimes forms a surface coat- 
     ing for slipware. Applied as a suspension of 
     fine clay particles in water. Slip ornament 
     may be applied by dipping the pot into the 
     suspension, carving, trailing through tubes, 
     combing, mixing (marbling or joggling), or 
     brushing. 
168 The Longridge Collection