history and characteristics

Ceramics is a unique art form that has been around since Prehistoric times. The first evidence of small clay sculptures date back to the Paleolithic people 30,000 years ago.

The word ceramic comes from the Greek word

κεραμικός (keramikos) meaning pottery.

Mostly likely, they made baskets and reinforced them with what they thought was “mud” which was actually clay and when they became corroded they would throw them into the fire. The basket would burn but the “mud” hardened in the shape of a bowl.

●A naturally occurring material composed primarily of fine-grained minerals, which show Plasticity through a variable range of water content, and which can be hardened when dried and/or fired.

● Different types: Earthenware, stoneware, porcelain

● After fired, becomes Ceramic

● Different colors

W H A T I S C L A Y ?

Clays workability directly related to amount of water in clay

If clay is too plastic you can wedge it or allow it to dry out more

If clay is not plastic enough water may be added

Clays ability to hold or absorb water. Directly related to plasticity and shrinkage.

As water evaporates from clay the particles once suspended in water start to come closer together creating shrinkage as it dries. Shrinks 3 times as water evaporates, bisque fire, and glaze fire.

Problems associated with shrinkage: – new clay cannot be added at different stages- must be crosshatched tightly – different thicknesses will make cracks

How do we use ceramics in our daily life?

Historical uses:first writing tablets, pottery for food storage, bricks, cooking pots, musical instruments, dishware, art objects (often religious), smoking pipes

STOP: with your table mates, write down as many things you can think of that we use today.

Modern uses: teeth, toilets, tiles (floor, roof, decorative), pipes (fluids), automotive parts, medical devices and implants, computer parts, architectural components (decorative and structural), weaponry, space shuttle parts, plus MUCH more...

1. Wetware2. Leatherhard3. Greenware4. Bisque5. Glazeware

Most plastic and may be used and reused to form different shapesEasiest stage for throwing on the potter’s wheel, rolling out slabs, coil building,

STOP: take out the wet clay from the middle of the table and feel it.

• Lost some plasticity

• Clay is dried to the point of stiffening up like leather, but still somewhat flexible.

• Best stage for:Alterations, trimming, assembling, stamps and carving

soft leather hard

2STOP: take out the soft leather hard clay from the middle of the table and feel it.

● Stiff enough to better support its own weight. Too stiff for fingerprints, or severe flexing

● Best stage for precision cutting, carving details, decorative slips, single-fire glazes (engobe, underglaze), removing armatures, burnishing, clean up and final preparations before firing

3STOP: take out the leather hard clay from the middle of the table and feel it.

● Completely lost all plasticity, completely dried out and ready to bisque fire.

● Usually turns a lighter color● This is the most FRAGILE stage!

Things that break in this stage are nearly impossible to fix

● Best stage for bisque firing or recycling

aka. Bone Dry 4STOP: take out the bone clay from the middle of the table and feel it.

● Clay has been fired for the first time (usually around 1940 degrees F) and becomes hard, Still able to absorb water, but will not deteriorate.

● Usually turns color again● Best stage for applying glaze,, high

firing, or alternative surface treatment● Broken pieces cannot be repaired or

recycled.

5

STOP: take out the bisque clay from the middle of the table and feel it.

6● Clay has been fully vitrified

● It has been to another temperature (1900-2455 F), depending on clay type and glaze

● Glaze is vitrified● Final stage. Enjoy or

destroy are the only two options

STOP: take out the glaze clay from the middle of the table and feel it.

3 Keys to attaching clay● Score

○ cuts that allow moisture to penetrate into the clay

● Slip○ Mixture of clay and water

● Pressure○ What makes the clay “stick”

● Looting (optional)○ “stealing” clay from one piece

and blending it with the other

Building Techniques● Pinch Pot● Modeling● Coiling● Slab Construction● Casting

○ Slip○ Press molds

● Throwing

Pinch Pot

● Simplest Technique● Can be used in combination

with other methods, primarily modeling

● Often used in conjunction with paddling

Modeling● Simply building the clay up by addition and

possibly subtractive methods● Most projects use at least some modeling● with or without an armature● If built solid, clay will need to be hollowed out

while leather hard● Can be very detailed● Often involves many sculpture/modeling tools● Works best for smaller projects

○ Usually too difficult for larger projects with an armature

Coil● Building up a form using

smaller coils (snakes) of clay

● With or without an armature

● Can be used for small simple pieces

● Can be used for large and complicated pieces

● Often used in conjunction with paddling and sometimes modeling

Slab Construction● Easiest way to make clay “walls” for containers

or sculptural pieces● Usually with an armature● Slabs can be used while still soft or leather hard● Requires good joint attachment● Works great for hollow forms● Slabs can be textured pre or post-construction● Walls can be straight, curved, bent, twisted, etc.

○ imagine they are almost like cardboard

Cast● Clay is formed using a MOLD

○ a mold is a negative form○ Clay is pressed or poured into the mold○ Once it becomes stiffer, the clay is

removed● Molds are great for making repeated pieces ● Can be straight cast, or “cast and altered”● Different types of molds

○ slip casting○ press mold○ multiple part single piece molds

http://youtube.com/v/vaUFN-q3_mk

Throwing● Using the potter’s wheel● VERY steep learning curve● Takes LOTS of practice and failure● Makes forms very quickly (after some practice)● Works great for functional pottery: vases,

bowls, cups, plates, etc.● Fairly limited to round forms● Can be straight thrown, or “thrown and

altered”● Very old technique● Vessels can range in size from a dime to 8’ tall

or bigger

General Rules of Clay

● Clay should be no thicker than ½” (thickness of your thumb) in at least one direction at the MAXIMUM

● Clay thinner than ⅛ (a little thinner than your pinky) becomes very fragile, especially while bone dry

● Clay dried unevenly or too fast will most likely crack in the kiln

● Clay fired while still wet will explode● Trapped air pockets will cause clay to capture

moisture and crack/explode in the kiln

Terminology You should know

Slip

● Clay and Water● In liquid Form● Can be used for casting, joining, or

decorating (slip trail)● Different things can be mixed in

easily at this stage

Kiln:● A thermally insulated chamber, a

type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical change.

● Most kilns reach temperatures of 1800 F. High fire can reach temperatures of 2400 F.

Dry footing - Leaving the bottom of bisque fired clay glaze-free so the glaze does not stick to the kiln in firing.