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< prev - next > Manufacturing handicraft process industries Pottery and ceramics KnO 100351_Modifications to a pottery wheel (Printable PDF)
Pottery is formed clay hardened by the application of heat, it includes a range of materials like
bricks and tiles, earthen-ware, stoneware, terra cotta, bone china and porcelain.
The potter needs clay and water to mix and form, and some source of heat to bake the formed
clay (in the early times the sun provided this).
Fired clay is fragile but is also almost imperishable under normal conditions. Thus fired clay
accumulated through the ages reveals man's evolution, his social habits, his ideas, interests and
Clay, a product of decomposition of mineral feldspar, can be classified broadly into two
categories -primary and secondary, according to its location. Primary clays are found near to or
among their mother rocks. Kaolins (China clays) are primary clays. Secondary clays are clays
which have been carried away from their source, collecting impurities on their way.
Clay Shaping Processes:
Clay can be shaped or formed by any of the following processes:-
a. modelling
b. throwing
c. moulding
d. jollying
e. extruding
f. pressing
g. turning
In modelling, which is undoubtedly, the most ancient and the simplest of the above processes,
shapes are formed entirely by hand using only the potter's fingers and a few rudimentary tools
like scrapers and knives. Large pots are made even today by coiling up ropes of clay and
smoothing the surfaces on the inside and outside as the shape builds up.
Throwing is the best known of all the shaping processes. The potter imparts his creativeness on a
lump of plastic clay spinning on a turntable, using his thumbs, fingers and palms. This paper
discusses the modifications effected to the throwing wheel, on which the clay is spun.
In moulding clay is pressed onto a mould having the negative form of the desired shape. The pre-
Columbian Americans, lacking the mastery of the throwing wheel, used moulding as their main
pottery-making technique.
The jolly consists of a Plaster of Paris mould on a rotating turntable and a profile tool attached to
a lever. Clay is placed in or on the rotating mould and on lowering of the profile tool the clay is
forced to take the shape of the contour of the mould.
In extruding, plastic clay paste is forced through a die or a mouthpiece with the required profile.
Clay is pressed in between two dies whose inside had been formed to the required profile of the
article, in the pressing process.
Clay turning is similar to metal turning on a lathe but the clay has to be air-dried to be hard
enough to with-stand the turning.
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