“Jonah” made with high
fire stoneware M340 clay."
We ended yesterday with two questions:
1) What you wish to make?
2) What kiln resources do you have?
The answers will be key to the choice of clay you
might chose to use. But, before we go there we must go back to the processed commercial
clays again.
Clays are divided into three main groups or
classes. These are low fire earthenware, mid fire Stoneware and high fire stoneware.
As you can see they are classed by their maturation firing temperature. The
clay bodies between the low fire and high fire clays are quite different, while
the two mid and high fire classes are also different but only in matters of
density etc.
Earthenware has been used most by mankind around
the world. It has the lowest maturation firing temperature so from the days of
antiquity it was easier to get results using different methods of an open fire using huge fires, often with the aid of stone walls, cliffs, caves etc. aids to get to the maturation temperature. This clay is still commonly used and is
distinguished by it’s usually reddish, brown, orange, colour(s). Another reason it
is used a lot is that it is very “plastic” and so easy to work with.
Earthenware’s firing temperature is between 1745 F - 2012 F (950 C – 110 C)
Stoneware has as mentioned, two classes, mid and
high fire. The latter consists mostly of a clay called porcelain. Mid fire
stoneware will be a grey, buff or tan kind of colour, while the high fire kind
will end up whiter. They are called stoneware because they are known for their hardness
and especially with the porcelain, it is very dense and hard. Some of the porcelains
of the highest temperature will actually become translucent when the walls are
thin. Maturation temperatures range from 2150 F to the top of high fire at 2336
F.
OK, back to the two questions, beginning with the
second. Not all kilns can do stoneware high fire clay. If you have a kiln
already, you will already know that. Can you rent kiln space near your
location? What are their capabilities? Answers to these questions will help in
your choice of clay.
Question number one, what you wish to make could
make a difference in your choice of clay. With each class of clay are many
different variations of clay. This has to do with the character of the body of
the clay. It basically, in a broad way boils down to how detailed will your
work be? How much will your work challenge the clay? There are some clays made to fit the best of both of these worlds.
That is just the kind of clay I have been using up till now. The photo of the "Jonah" piece above is made
with mid fire stoneware M340 clay. You can see, there is a lot of detail in
this piece. I think I pushed the envelope a bit as a lot of artists were surprised what I was able to do with this clay. (Ignorance is bliss!)
For my next piece, I have entered into the world of
porcelain. I am still in the creation stage and love the feel of the clay. I am
finding it enjoyable to work with. We will see how things go with the firing
and the finishing of the piece. I will keep you posted.
“Remember that you molded me like clay...."
Job 10:9
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