Pottery Vocab And Facts

Front 1

Absorption

Back 1

the amount of water that a clay body is able to draw into its surface at a particular stage in the ceramic process.

Front 2

Atmospheric water

Back 2

"wet" water that leaves the clay as it dries to the greenware stage and prior to the bisque firing

Front 3

Biscuit or Bisque

Back 3

the first firing(to 1800 degrees/cone 06)which makes the clay stronger yet porous and drives off its chemical water

Front 4

Chemical water

Back 4

water that is chemically bonded to the orginal clay but released during the bisque firing(through the process of sintering) at between 8-900 degrees- it dissipates inot the atmosphere, permently changing the clay and making it no longer able to be slaked.

Front 5

Clay body

Back 5

a useful mixture of ceramic materials combined for a specific purpose

Front 6

Colorants

Back 6

highly refined oxygen/mineral compounds that are added to a clay or a glaze to color it

Front 7

Earthernware

Back 7

clays that remain highly porous even when fired to their maturing tempature (cone 4 and below), have a darker reddish brown color, a coarse particle size, and are made up of large quanities of secondary clays; i.e.- terra cotta

Front 8

Engobe

Back 8

a combanation of ceramic materials that is halfway between a clay and a glaze and is "self-glazing" when fired on the surface of a pot

Front 9

Fireclay

Back 9

clay that is resistent to high tempatures( kiln shelves, supports and bricks are made from fireclay)

Front 10

Flux

Back 10

the lowest melting ingredient in a glaze, which causes the other ingredients in the glaze to also melt

Front 11

Glaze

Back 11

a combination of ceramic materials, that is applied to bisqueware and when fired to its maturing tempature melts and fuses into the clay to create a durable glassy surface

Front 12

Glaze firing

Back 12

the second or high firing(called "glost" firing by the british) which fuses the clay particles tightly together and matures the clay; also makes the clay body stronger and less porous and permanetly bonds the glaze to the clay body

Front 13

Greenware

Back 13

dry unfired clay which has lost all of its atmospheric water, become very fragile, and lighter in color and weight

Front 14

Grog

Back 14

fireclay that has been fired, ground up, and added back to a clay body- adds stability to the clay by helping to control the amount and rate of shrinkage in the drying and firing process

Front 15

Kiln

Back 15

a high tempature refractory oven used to fire clays and glazes to maturity in a controlled environment.

Front 16

Leatherhard

Back 16

half-way dry clay, displaying the characteristics of leather; i.e.pliable yet firm, without a surface "sheen", and resistant to showing fingerprints when touched

Front 17

Matte glaze

Back 17

a glaze with a crystalline surface structure that refracts and diffuses light to produce a soft and nonreflective appearence

Front 18

Mature

Back 18

the condition where a clay or a glaze is fired to its maximum firing tempature without it slumping, collapsing, distorting, or in the case of a glaze, is fired hot enough to melt the glaze without making it run

Front 19

Oxidation

Back 19

a kiln atmosphere in which sufficient oxygen is available to allow for a complete fuel combustion with little or no carbon monoxide being produced.

Front 20

Peep hole

Back 20

the view hole in the kiln through which the cones can be visually inspected to see if the firing is completed

Front 21

Plasticity

Back 21

the ability of a clay to be stretched or expanded without breaking, tearing, or collasping

Front 22

Porcelain

Back 22

a fine textured vitreous clay body that is usually light in color and relatively nonplastic because of the high amounts of kaolin that it contains

Front 23

Pottery

Back 23

useful ceramic objects made of clay

Front 24

Primary clay

Back 24

clays that remain close to their origin, remain relatively pure and light colored, have large particle size, are nonplastic, and are deposited in vertical beds(kaolin is our best example)

Front 25

Pugmill

Back 25

a machine used to mix clay; often able to remove unwanted air in the process

Front 26

Pyrometter

Back 26

an instrument used to measure high tempatures within a kiln(uses an electric current created when nickel and chromium metals are joined together and heated to high tempatures)

Front 27

Pyrometric cones

Back 27

small cone shaped pieces of clay that are carefully manufactured to melt at very specific tempatures; these show when the appropriate peak tempature has been reached inside of the firing kiln

Front 28

Raku

Back 28

a japanese reduction firing technique in which red hot pots are removed from the kiln when the glaze has matured, and then placed into an airtight metal container with paper, sawdust, leaves, straw, or another source of carbon; produces carbon monoxide and gives color to the glaze.

Front 29

Reduction

Back 29

a kiln firing where there is not enough oxygen present for a complete combustion, creating a "reducing" atmoshpere within the firing chamber, and large quanities of carbon monoxide.

Front 30

Refractory

Back 30

materials that are resistent to high tempatures (high in alumina and silica, refractories are used to make kiln bricks, shelves, and support furniture items.

Front 31

Secondary clay

Back 31

clays that travel a great distance from their original source(granite type rocks), picking up organic and mineral impurities along the way; they have small particle size, are plastic, shrink excessively, are dark in color, and are deposited in horizontal beds(ball clay is our best example)

Front 32

Sgraffito

Back 32

a decretive technique where the surface of a clay or glaze is carved through to allow a contrasting color to show from underneath.

Front 33

Shards

Back 33

broken pieces of fired clay

Front 34

Slake(slaking)

Back 34

the process where-by water is added to dry clay causing it to "melt" as it becomes moist and returns to a workable state.

Front 35

Slip

Back 35

clay in liquid suspension

Front 36

Stain

Back 36

a coloring oxide (colorant) mixed with water and applied to bisqueware to enhance a textured surface, or applied over a glaze to provide concentrated color in a specific area

Front 37

stoneware

Back 37

a blend of clays that when fired to maturity(between cones 4 and 10) becomes hard and durable, retaining a porosity level between 3% and 5%.

Front 38

Terra cotta

Back 38

a reddish brown earthenware clay that is commonly used for planters due to its porosity, almost universal availabilty, and economical cost.

Front 39

Vitreous

Back 39

hard, dense, and glasslike

Front 40

Warping

Back 40

distortion of a ceramic form caused by uneven drying, uneven heat flow through the kiln during firing, or placement on an uneven support surface for firing

Front 41

Wax resist

Back 41

applying a wax material to clay to seal its surface so that glaze can no longer be absorbed into that surface.

Front 42

Wedging

Back 42

the physical process of working clay on a flat surface to eliminate air, make the clay homogenous, and increase its plasticity.