There are many types of clay.
Variances in clays are a direct result of the materials
that were broken down to form raw clay.
is one of the purer forms of clay,
basically composed of kaolin.
This type of clay vitrifies at higher temperature ranges
from 2300 degrees F.
and can withstand much higher firing temperatures
without melting or slumping.
Porcelain clay when fired is very white.
is a courser form of high firing clay containing kaolin
as well as, lower firing clays.
It may also include iron, which results in it's off white to reddish appearance before and after firing.
This clay can also be formulated to withstand
temperatures equal to porcelain.
is considered low fire clay. It vitrifies at much
lower temperatures 1000 degrees F,
but can melt to a liquid as low as 1300 degrees F.
Deposits of clay can be found in their natural state that
can be used to make pottery.
As with any natural deposit, it may not be consistent. Therefore,
clay bodies, are generally formulated by using clays
from different deposits and
adding silica and feldspar to aid their plasticity and firing consistency.
When deciding which clay to use, consider these variables:
what type of piece, it's function and firing temperatures.