
Forming processes and
techniques Porcelain differs from other ceramics such as terra
cotta, stoneware and earthenware by its whiteness, translucency,
impermeability, durability and resonance.
PASTE:
composed primarily of three natural occuring rocks;
Kaolin (Chinese for «high hill»): base ingredient
in porcelain (55%), a very pure and plastic clay. Quartz (20%):
a degreasing substance enabling the porcelain to hold its
shape under firing.
Feldspar (25%): soft element allowing for the fusion of the
mixture.
MANUFACTURING:
early methods of transforming these raw materials into objects
were e done by hand. The paste was moulded, turned or stamped.
This was a difficult process and is still used today when
making prototypes or artistic objects.
CASTING:
The pacte in its liquid form is poured into a hollow plaster
mould, leaving a layer of clay on the surface of the mould.
The cast is then removed after a period of time. This method
is used to make hollow or sunken pieces such as vases, soup-tureens
and coffee/tea pots.
JOLLYING/JIGGERING
Used to make round objects such as plates, saucers, cups,
etc., this method uses a semisoft round shaped paste set flat
on a spinning mould. A blade is set at the desired thickness
and any excess is cut off.
PRESSING
Hardened granular paste is injected by steam pressure into
the two sides of the mould.
FIRING:
after the piece is dried and finished, it is ready for its
first firing. It is placed in an electric kiln at 980*. The
piece becomes dehy-drated and porous and is now entirely dipped
in glane. A second and final firing is done in a gas kiln
at 1400*. The piece is now vitrified and has lost 15% of its
original volume and dimensions. The porous gray mixture has
become white, translucent, impermeable and resonant.
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