Kinds of Ceramics
porcelain: what's the difference?
first ceramics archaeologists have found date back
more than 10,000 years. These were earthenware, which
means they were made from clay and fired at the kind
of low temperatures reached by a wood fire or simple
oven, between 1202°F (650° C) and 1832°F (1000°).
This is still pretty hot when you think how hot your
oven at home gets, which is probably about 450°F (230°
C) or 500° F (260° C).
There have been ceramics almost
as long as there have been human culturespeople
have always needed vessels to cook and store food
Most earthenware vessels, such as terra cotta flowerpots
that you may have at home, are not waterproof. They
can be polished (or burnished) to close the pores
after firing or covered with glaze and fired again.
In China, most ceramics made before the Tang dynasty are earthenware.
They may be unglazed and painted or they may be glazed. Their glazes
contain lead and are often brightly colored.
The Han horse above is unglazed earthenware. The
acrobats to the right are painted earthenware. [Click
on any image for larger view.]
Stoneware ceramics are harder and less
porous than earthenware and are fired at hotter
temperaturesbetween 2102°F (1150°C) and 2372°F
(1300°C). At these high temperatures, the surface
of the clay melts and becomes glassy.
Although stoneware is usually waterproof, most
ceramics are glazed for decoration. The glazes often
contain ash, which allows the glaze to harden at
The bowls to the left are glazed stoneware.
Porcelain was first made in China in the 6th and
7th centuries AD from porcelain clay (known as kaolin,
after the Gaoling Mountains of southeastern China).
Chinese potters mixed the kaolin clay with a powder
ground from a stone called baidunzi, a rock
that contains feldspar, a glassy mineral. It is
fired at very high temperatures above 2372°F (1300°C),
causes the surface of the clay to melt and become
smooth as glass.
Early porcelains were undecorated and were used
by the Imperial court and exported as far as the
Middle East. Blue and white porcelain is painted
with blue paint made from cobalt and then covered
with a clear glaze, which can withstand the high
temperatures of the kiln. Other kinds of porcelain
are painted after the object has been fired in the
The word "porcelain" comes from an Italian word
porcellana or "little female pig,"
the Italian name for small white cowrie shells.
The first Italian travelers to China saw beautiful
Chinese porcelains and thought that these ceramics
were made from ground-up sea shells. The name has
remained, however, even though they are not made
This plate is an example of blue and white porcelain.