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Studio
pottery is divided in three main groups:
Like
stoneware, porcelain was first developed in China. The firing range
of true, or hard-paste porcelain is above 1200°C reaching up to 1400°C.
Porcelain bodies do not occur in nature and are composed from kaolin
and cornish stone, a feldspathoid (mineral similar to feldspar but with
smaller
silica content) that works as a flux, melting to a stiff glass.
Porcelain fires white andtranslucent, and has great mechanical strength,
allowing the making of extremely thin walled vessels.Usually the body
is covered only bya thin layer of transparent glaze, but coloured and
opaqueglazes may also be used. Germany was the first European country
to unveil the secret of porcelain, but only in the eighteenth century.
Soft-paste porcelain is fired at lower temperatures, is of European
origin and due to its lack of plasticity can only be formed by casting.
The two main types of soft-paste porcelain are china and bone china.
Hard-paste porcelain is also difficult to form with the traditional
methods used by the studio potter, and is prone to collapsing, deforming
and warping during the firing. EARTHENWARE Earthenware is pottery fired at low temperatures, between 900and 1150°C. The body is porous and a glaze is necessary to obtain waterproof vessels. Earthenware has reduced mechanical strength and needs thicker wall construction. Glazes form a film on the surface of the pots as opposed to stoneware glazes, which form a unity with the body. A wide palette of bright colours is available to earthenware. Fayence and Maiolica and Delft are earthenware types, as is most painted ware. This was the first type of pottery ever made, dating back to 12'000 years ago, making it one of mankind's oldest activities. STONEWARE Type of pottery fired at temperatures ranging from 1150°C to 1400°C. At these temperatures, vitrification occurs, giving a non-porous body with great mechanical strength. Glazes interact with the body and do not necessarily need to be waterproof, therefore dry, matte finishes are possible. A reduced palette is available to the potter working with stoneware, because most of the pigments used for earthenware do not withstand high temperatures, but effects of great beauty in subtle shades are possible. The first examples of stoneware were made in China 2000 years ago. In Europe it was first introduced in Germany around the year 1000. PORCELAIN |