Ceramics (the stages of clay)

What is clay?

A mix of naturally occurring made up of primarily of fine-grained minerals. Very finely ground up rock. The fine particles are suspended in water.

Why do different colors occur in clay? What makes red and white clay?

Because of impurities in the clay. Red clay is the results of Iron Oxide in the clay, while white clay gets their color from Talc in the clay body.

What are "the stages of clay"

it refers to the different amounts of water mixed with the minerals that make up the clay. + more water makes the clay softer to the touch. - Less water makes the clay harder to the touch.

What are the 6 stages?

Slip, plastic, leatherhard, Bone dry/greenware, Bisqueware, and glazeware

What is slip? What are other uses?

25% clay, 75% water. It is liquid clay, used to attach 2 pieces of clay together , "glue" of the pottery world, putting/yogurt consistency is the best, other uses of slip include decoration with slip trails or filling cast molds.

What is plastic?

50% water, 50% clay, soft, pliable clay, in this stage we can easily pinch, coil, free form sculpt, of throw clay on the pottery wheel, this is the stage you will receive your clay in.

What is leatherhard?

75% clay, 25% water, best stage to carve or add designs to your clay, clay that will hold it's own shape- similar to a leather boot, ideal stage when connecting slabs together.

What is bone dry/greenware?

stage 4. 100% clay, 0% water, most fragile stage of pottery, the clay should no longer be cool to the touch once it's 100% dry, don't try to add or subtract from the clay in this stage, ready to be fired.

What is bisqueware?

stage 5. Clay that has been fired once, fired clay is no longer recyclable, the clay body will change color once it has been fired and is now ready for painting or glaze if the artist chooses.

What makes the clay process permenant?

clay must be fired in a kiln to make it permanent, the kiln heats the clay up to 2000 degrees to fuse the minerals in the clay together.

What is glazeware?

Stage 6, pottery that has had glaze applied to it and fired 2x , most glazes are shiny and resemble glass,

What is wedging and why do we do it?

In the wedging process, clay is repeatedly kneaded, distributing the moisture evenly and eliminating hard spots in the clay. In the process, air bubbles are forced out of the clay, ensuring that these bubbles will not heat and cause the clay to explode in the kiln. Properly wedges clay is very smooth and pleasant to work with.

What does it mean to fire pottery?

Firing is the process of applying sustained heat to clay in order to change clay into permanent pottery or ceramic.

How is pottery fired?

Clay must be raised to the correct temperature to bring about this magical transformation. To do this, the unfired pottery is placed in a kiln and the temperature is gradually raised over a period of hours until it reaches the proper temperature.

How hot does the kiln need to get?

Depends on what kind of clay of glaze you are firing, but low fire= approx. 1900F, high fire= approx. 2300F.

What are the steps in the firing process

Greenware, Bisque-fire, and then glaze fire

What is glaze

(Glass and chemical colorant mix) a form of glass that will fuse to the surface of the clay used to decorate and waterproof pottery

How do you avoid project blow ups in the kiln?

Avoid putting wet clay in the kiln, Avoid trapping air bubbles in the clay, Avoid drastic temperate changes, Avoid making walls thicker than 1 inch.

Shrinkage

As pottery is dried and fired it loses volume due to all the lost water. The rate clay reduces in size as it is fired into permanent ceramics. Different clay bodies have different shrinkage rates depending on their characteristics.

Warping

An uneven drying problem that causes pottery to be distorted as it dries and is fired. Warping is usually a result of uneven thickness in the clay.

3 names of a kiln

Trash can, gas kiln, fire pit

What happens when a project dries?

Shrinks, lighter color, gets warmer

Which stage must clay be in before first firing?

bone dry

What is slipping & scoring?

a basic pottery and ceramics method used to securely attach two pieces of clay together

What is wedging?

the process of kneading, cutting, or slamming a material like clay to remove air pockets, even out moisture, and create a uniform consistency

What is clay made out of?/where does it come from?

Mix of naturally occuring materials made up of primarily of fine grained minerals. Like very finely ground up rock, it comes from the ground. The fine particles are suspended in water.

At what stage is clay no longer recyclable?

bisque fired/glazed fired

3 types of kilns

electric kilns, gas kilns, and wood-fired kilns

Firing temperature

Low fire- approx. 1900F, high fire- approx 2300F??

loop in ceramic tools

ribbon in ceramic tools

needle tool in ceramics

rib in ceramic tools

wooden modeling tool in ceramics

sgraffito tool in ceramics

wire tool

banding wheels

fettling knife

plastic bat

pottery wheel

kiln