CALIPER:
Form your left thumb and left index finger
into the letter c. The distance between their tips can be fixed and used
as a crude measuring device. A caliper is an insturment made of metal or
wood that can accurately serve the same purpose.
CAST:
A cast is a negitive form made of
a ridgid absorbant material to produce multiple copies of an identical form.
The process of pouring specialy formulated
liquid clay or forcing a soft clay body into a mold. Dolls, bowls and
decorative vases have been cast with ceramics for thousands of years.
CELIDON:
A Chinese glaze ; pale green-grey color;
popular for thousands of years.
CHEESE HARD:
This must be a British or Austrailian
term refering to our word “leatherhard”. It makes sence.
Haven’t you seen old dried chedder in the back of the refridgorator drawer?
You could carve it or break it with a bend.
CHINA:
When porcelain was first imported to Europe
it was called china. WOW ! It was white. At that time, European potters could
only produce earthen colors from wood or coal kilns.
Delft tin glazing was among the first methods [ glazes ] to produce the
illusion of a white clay body.
CHITTERING:
The rim of a pot can fire improperly if
it was poorly cleaned or finished or, perhaps too thin.
The resulting inconistant edge is called chittering.
CHUCK:
A hallow cylinder of clay; made on the
potter’s wheel. A chuck is used to hold a tall vase up / side down,
vertically, in order to trim the bottom.
For more information:
CLAY:
Ya know the rain cycle? Water evaporates,
raises into the sky, accumulates, gets to heavy to float as a gas, falls as
rain on the mountains; as it rolls over the rocks ,it picks up small
particles and carries them to streams, rivers and down to the sea. Well,
those slimey little particles that accumlate on the river bottoms are
what we call clay. Over the millinia they form deposits and we mine it.
When heated to a high temperture it is no longer soluable in water and
it becomes permainently hard.
CLIMBING KILN:
A multiple chambered kiln that passes heat
from one chamber to the next as it climbs up a hill side .
COASTERS:
Ordinary coasters can be bent, slightly,
to use as "ribs" when forming the inside of pots on the wheel. In fact, any
round aluminium disc can be formed to use as a rib.
For more information:
CO-EFFICIENT OF EXPANSION:
The measurment of how much clay shrinks
after firing. A 10 mm line is drawn down the length of a small slab of raw clay.
Each end of the line is crossed to exactly mark the beginning and end of
the line. The clay is properly dried and measured before and after firing.
There are now three measurements: 1. 10mm wet 2. dry 3. fired.
Clay tipically shrinks 5 % to 7 % at each stage. Twelve per cent does not
sound like much. But, It means a 10 inch [ 26 mm ] pot on the wheel will
shrink more than one a inch [ 2.5mm ] after firing. WOW !
COILING:
Clay is rolled back and forth to create
a snake-like form. This is called a coil. When a coil is made into a circle
and sucessively placed one on top the other or one conyinous
spiral; one layer on top of it self; it forms a cylinder.
This is called coiling.
COMPRESSOR:
An air compressor is a valuable asset
in the clay studio. It can be use to blow off ware before glazing and spraying glaze.
For more information:
CONE:
Originally, cones forms were made of
the glaze the potter was using. These cones were set insde the kiln in
front of a peep hole. As the temperature of the kiln rose, the cone
would melt in front of the peep hole telling, the potter it had
reached the right temperature. Unfortunitly, it was unreliable and
inconsistant. Then potters varied the glzae mixture to be just above
or just below the right temperature. Setting three cones in a row by
a peep hole,
the potter could predict just when to stop stoking the fire.
Modern potters buy accurately formulated cones compounded to melt
at specific tempertures. Firing consistantly is an art that relies
on science and experience.
CRACKLE:
1.One of the three sounds rice crispies
make when you add milk [ snap and pop are the other two sounds ] 2. When
glaze melts, it is a molten liquid covering the piece. As it cools and
turns back to a solid, it shrinks. It does not always fit the clay body.
Since it is not elastic and flexible; it cracks. When a glaze or colorant
of another color is rubbed into the cracks, the cracks are more visable.
Sometimes, the oxygen in the kiln is reduced during firing. When the
glaze shrinks; black carbon fills the cracks, leaving the cracks visable.
Craclke glazes are specially formulated to do this on purpose. see crazing
CRAWLING:
If glaze is applied too heavily, the
consequence can be seporation of the glaze from the clay. It looks as if
the glaze crawled away from an area. It may look like the remnent of a greasey
finger print. Bisque clay readily absorbs oil from finger
prints, nose or elbow bumps. These are commons reasons for the glaze to crawl
away from an area ; leaving bare spots on a glaze fired piece.
For more information:
CRAZING:
This is the name for the unpredictable
pattern of cracks in the glaze after it cools.
It is a form of the word crazy; unpredictable random behavior.
On earthenware pottery crazing is considered a undesirable fault. For
food serving ware, it permits liquids to penetrate the glaze and foster
bacteria. Out door planters will fracture when they freeze, if the glaze
allows water to enter the clay body.
CRYSTALINE GLAZE:
A really cool glaze that grows crystals
on the surface of the ceramic piece during firing. The crystals are often circular
or star shaped and look like frost on a window; in color.
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