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Ceramics AR120
Vocabulary part II
40
Other
Undergraduate 1
05/06/2009

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Term
Glaze
Definition
Any vitreous that has been melted onto a clay surface byt the use of heat and is composed of silica(glass former,) alumina (stifferner) and flux.
Term
vitreous
Definition
pertaining to or made of glass, glasslike
Term
colorant
Definition
the natural mineral (like red iron oxide) or commercial ceramic stain that is added as a percentage to the glaze formula.
Term
batch formula
Definition
the proportion of actual weights of the raw chemical componds that make up the glaze for a specific temperature.
Term
flux
Definition
a catalyst that lower the melting or fusion temperature of another material
Term
frit
Definition
a glass that is commercially made by melting a flux (either soluble or toxic) with silica. Used as a component of glaze production.
Term
Bisque firing .
Definition
the first low temp. firing between 1650 and 1950 degrees F.) of clay which renders it porous, relatively strong and easy to glaze.
Term
Glaze Firing
Definition
the firing of glaze coated bisque work, usually to a higher temp. that makes the clay body dense, hard, and vitreous or glasslike.
Term
dunting
Definition
the thermal crack that is a result of uneven temp. application. It occurs at 1062 degrees F
Term
glass former (SIO2)
Definition
the compound in the glaze that produces glass.
Term
stiffener (ALO2)
Definition
the compound in the glaze that lessens the elasticity of the glass and helps tp prevent the glaze from running
Term
egyptian paste
Definition
a clay infused with soluble salts that act as a flux to produce a "self-glazing" clay. Oldest glaze known and found in Egypt from 5000 B.C.
Term
Lead glaze
Definition
very low temp. melting glaze and discovered in the Near East around 1000 B.C. toxic
Term
Ash Glaze
Definition
discovered in China in association with high temperature Kiln technology. can only be used above 2150 degrees F
Term
slip glaze
Definition
a naturally occuring clay that has sufficient flux in it to becomes a glaze when fired to high temp. Albany clay from NY is an example of this type of clay.
Term
engobe
Definition
a colored clay slip applied clay to the surface of pottery or sculpture to change its color and/or texture.
Term
feldspathic Glazw
Definition
a glaze compose primarily of feldspar used in high temp. stoneware ceramics. By itself, feldspar, when fired to a high temp. (2300 degrees F, will yield a milky white glaze.)
Term
celadon
Definition
an old fashioned term that refers to the cool, gray/green/blue color of a high temp. glaze when fired in reduction, iron is the colorant.
Term
oxidation
Definition
refers to the efficient combustion of a fuel. Ample amount of oxygen is available so that the most energy is released. The flame is characterized as being short and cule in color.
Term
reduction
Definition
refers to the inefficient combustion of fuel, that is, not enough oxygen is available for combustion. The flame is characterized as being orange, long and smoky
Term
carbon monoxide
Definition
is produces in a reduction firing. It is "unstable" and will steal oxygen from the oxides that comprise the clay and glazes of the ceramic work thus changing their color and texture.
Term
combustion
Definition
three items are necessary for this process to occur: furl, oxygen, and ignition temp.
Term
convection
Definition
transfers of energy from one place to another through the process of heated airrising
Term
conduction
Definition
transference of energy through physical objects just as ceramic objects and materials
Term
radiation
Definition
emittance in all directions of energy from its source to surrounding enviroment. The hot kiln "radiates" energy
Term
pyrometer
Definition
the electromechanical device that indicates temp. at a certain moment in time.
Term
thermocouple
Definition
the bimetal probe inserted into the kiln that produces a small electrical charge when heated
Term
pyrometric cone
Definition
the tetrahedron shaped device manufactured by Orton Cone foundation that is placed inside the kiln to record the affect of heat over time on the ceramic materials.
Term
warning cone
Definition
the first of three cones that indicate that glaze temp. is almost reached.
Term
Desired Cone
Definition
the second cone that is the temp. at which the clay and glazes mature
Term
Guard cone
Definition
the third cone that indicates whether or not the kiln has been over-fired.
Term
Bat
Definition
a plaster, wood, or plastic disk or slab used support wet clay.
Term
Centering
Definition
the act of forcing a lump of clay by hand into a symmetrical form at the center of a spinning potter's wheel in preparation for throwing pottery.
Term
Kiln
Definition
a furnance or oven built of heat-resistant materials for firing ceramics items
Term
dry footing
Definition
that process of in suring that no glaze remains on the bottom of the pot do that it will not fuse to the shelf durign firing . Sometimes wax ressit medium is used as an aide to prevent the glaze from fusing the ware to the shelves.
Term
peep hole
Definition
the opening in the kiln opposite the site where the cones are placed
Term
quartz inversion
Definition
the temp. 91062 degrees F) at which dunting occurs
Term
porcelain
Definition
a white, high temp. clay body
Term
Earthenware
Definition
a red, low temp. clay body colored by iron oxide
Term
Stoneware
Definition
a high temp. clay body colored by less than 2% iron oxide
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