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Is Porcelain
Pottery
Basically
yes in that any article made of clay and fired or baked at a
high temperature is pottery!
There are
two types of pottery - earthenware and stoneware.
Earthenware -
pottery is defined as earthenware if it has a porosity of more
than 5% and can only be made waterproof with the application of
a glaze but because it is usually fired at a lower temperature
the glaze is not fused and can be penetrated by water.
Stoneware -
pottery is defined as stoneware if it has porosity of less than
5%. It is fired at higher temperatures (up to 1400C) than
earthenware and during the first firing the body and glaze fuse
together to become vitrified like glass. Stoneware is heavier,
opaque and more durable.
Porcelain -
porcelain is regarded as a special type of stoneware in
that it is fired to a state of vitrification. The difference is
that porcelain is translucent which is obtained by the type of
ingredients used. Porcelain is first fired at 900C, a glaze is
then applied and the article refired at up to 1600C achieving
vitreosity in this second firing.
Porcelain by
Robert Haviland & C. Parlon
There are 3
types of porcelain - bone paste, soft paste and hard paste
(paste is the basic clay and other minerals mixed together to
form an object). Bone paste or bone china (the main type of
china from England) is made from at least 50% animal bone ash
and is mixed with china clay and feldspar. Soft paste porcelain
has been made in Europe since the 1600s and was attempting to
emulate the hard paste porcelain of China. The manufacturing
process was difficult to control, the ingredients not natural
(sometimes ground glass) and the porcelain softer often leading
to scratching and patchy translucency. Hard paste porcelain (the
type manufactured in Limoges) is regarded as a natural porcelain
in that the ingredients (Kaolin and Feldspar) are obtained from
the earth.
Hard paste
porcelain became the basis for German and French porcelain
manufacturing.
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