Introduction to ceramics

What you need to know to get started…

Clay is….. Weathered, decomposed Granite (rock). A Clay Body,

is pure clay mixed other materials to make a desirable colour and texture of clay.

Earthenware: the type we will use. Fired at 1015-1200 C comes in red or white This is a “LOW FIRE” clay. Other clays are fired much hotter!

Stoneware Clay: fired at 1200-1250 C.

Porcelain: Fired at 1250-1350 C. Very fine clay. When it is fired it looks almost translucent.

Most clay objects are mass produced using casting slip and a mold“slip” is liquid clay. Molds are

made and the slip is poured in. Many identical molds can be made and this is the way ceramics can be mass produced.

Video link: casting a cup

Video link:Casting

Clay can be formed on the potters wheel

A lump of clay is magically transformed into a vessel

Video clip:tips for Throwing a Tall cylinder

Clay can also be formed using “HAND BUILDING TECHNIQUES” No wheel is required. The results are unique and equally valid Technique #1:Pinch Pots

Pinch Pots are created by inserting your thumb into a small clementine sized ball of clay. Slowly pinching in 3 rounds to thin the walls to an even thickness.

Technique #2: Coil “worms” of clay are rolled to an even thickness and

stacked one on top of the other to create any type of vessel you wish.

Technique #3: Slab After wedging, clay is rolled out into a “sheet”

that is even thickness. It can be made into a variety of things from a

mug, bowl, vase, platter…

These pieces have been textured when the clay is still moist

Process: working with clayAir OUT Moisture IN

Air Out Wedge the clay to rid it of air. Trapped air will cause your piece to blow (up) or at lease break.

Moisture in:While working with your clay, keep it wrapped in plastic. Then it will be workable the next day. Otherwise you will have to start over.

Process: Build your piece: 2-6 days Let it dry: 1-2 weeks (covered at first so

it dries slowly)

At this point your potter is called GREENWARE. It is very, very delicate because the moisture is leaving it and it is dry an fragile.

Process: First Firing:Bisque When your piece is TOTALLY DRY, your

teacher will place it in the KILN This is the first, or BISQUE firing Your clay will harden and SHRINK by

15%

Kilns: so many different types A kiln is a heating chamber for pottery You can heat by electricity, wood…

A typical oven cooks at 350 degrees Fahrenheit/ 176 C.Our kilns reach 1200 C or 2192 degrees FahrenheitA hot day is 32 degrees C or about 90 degrees Fahrenheit

A firing mould in Africa

A tile kiln

A charcoal kiln

Wood firing kilns

Safety in the ceramics studio:The Kilns They are very hot. Don’t touch them or

place anything on them. Assume they are ON.

Fumes: firing pottery gives of a smell. We have an EXHAUST HOOD above the kilns to take away fumes.

There should be no physical “horseplay” in the studio. No pushing, shoving, tripping. Someone could fall into the kilns and be burned. Any behaviour such as this will result in losing privileges in the studio.

Colour on Pottery We use two kinds of colourants on

pottery #1: UNDERGLAZES: They can be put on greenware or

bisqued pottery You may mix them and use them

like paint They fire to a MATTE surface If you want them to be shiny you

must put a clear glaze over them and fire a second time.

#2: Glazes Glazes are applied AFTER the bisque

firing They are colour plus shine all at once They should not be mixed together Some are opaque and some are

translucent.

Matte glaze: not very shinyGlossy Glaze: shiny

Second firing: glost/glaze Once the piece has been glazed with its

final coat, it must go into the kiln a second time.

The process from start to finish is about 3 weeks, including building, drying, firing, glazing, firing….fini!

Other safety concerns Sharp tools: be careful using exacto knives

and b3knives. Use common sense Electric shock: often we will have hair dryers

out to speed up drying. NEVER, NEVER let them touch water.

Silica: Silica is a component of clay. When it is moist, it is not a problem. As clay dries and becomes dusty, it is easily inhaled. ***CLEAN CLAY UP WITH MOIST SPONGES*** DO NOT SWEEP OR BLOW DUST AROUND***

Finally

In order for us ALL to enjoy this class, we have to agree to clean up after ourselves always, and to help others when asked.

Clay is messy. Tools get messy. Hands get messy. Rolling pins get messy. It all has to be cleaned before being put away. If you do not clean it and you put it away dirty, the clay dries, becomes dusty and then poses a health risk to everyone. Please do your part and help others when possible.