Introduction to Clay


Is a part of the earth

Is made workable with water

Is dried by the air

Is made durable with fire


Clay is the most important single material used in ceramics.  Potteries first developed alongside river banks where the action of the stream exposed clay beds.  Although we will be using clay to make pieces of artwork, clay is also used industrially in the United States to create such items as bricks, building and drainage tiles, plumbing fixtures (toilets and sinks), electrical insulators, and linings for steel and glass furnaces.

Seldom can one successfully use clay just as it is dug from the ground.  Depending upon its origin, clay usually contains large impurities such as vegetation matter or rocky debris.  Although our clay will come ready-to-use in a plastic bag, it is important to know the process by which it arrived in this form:

1)     Dig up a lump of clay and let it dry completely.

2)     Pound with a mallet into a coarse powder.

3)     Sift through a ˝ inch mesh screen to remove large pebbles, roots and impurities.

4)     Pour the powdered clay into a bucket of water.  Let set until clay has soaked up the water.

5)     Stir occasionally until all lumps disappear.  This may take several days.

6)     Strain the clay through a 14 to 16 mesh sieve.  The clay should be in slip (soupy, watery form) form for this process.

7)     Allow the clay to settle, siphon the water off the top.  Place the clay on plaster bats to absorb excess water. 

The process of making something out of clay can be extremely simple as well as very complicated.  Even thought the clay can take any shape given to it, because of stress, improper balance of weight, incorrect methods of joining, or improperly constructed walls, it may not always hold. 

Even if you do get a piece to hold and dry in the desired form, you have to make sure you haven’t sealed any air inside.  All hollow spaces must have a hole to the outside so air can flow in and out during the firing process and explosions can be prevented.  It is also extremely important that you don’t make any portion of your work thicker than ˝”.  That dense of a piece of clay will not be able to withstand the extreme temperature in the kiln and will explode.  All large objects must be made hollow, with walls no thicker than ˝” and a small hole allowing passage of air in and out of the hollow space.

Clay Methods

There are three common methods to creating basic constructions:  pinch, coil and slab.  To make a pinch pot, make a small ball of clay the size of a tennis ball or less, and stick your thumb in the center, making a hole.  Then apply pressure with your fingers on the outside and thumb on the inside, creating a rounded bowl shape.  You can easily join two of these shapes together to create a spherical form that could be the body or head of an animal figurine, bird house, etc.

Creating a coil pot or coil structure is repetitious, slow and tedious, but the results can be extremely pleasing and original.  To make one, create a coil by carefully rolling a lump of clay with all 8 fingers so that it is a nice and even thickness.  Coil it upon itself to create the bottom of the pot.  Make another coil of the same thickness and attach it to the end of the first coil, carefully smoothing them together.  Finish the bottom of the pot if necessary, then allow the coils to go on top of one another.  The closer in you go, the more the pot will taper in.  Putting the coils more towards the outside will make the pot expand outwards.  You can create some interesting effects by making the coils go in and out in this manner.  If you desire a smooth look, you can smooth the coils as you go.  You could choose to smooth just the inside and leave the coil appearance on the outside.

The slab method allows for the most variation of creations.  One can make just about anything out of a slab.  A slab is made by rolling the clay with a rolling pin to an even thickness.  It works best to have guides of the same thickness that the clay is to be.  The rolling pin rolls over the guides with the clay in between and keeps all the clay the same thickness, preventing you from pushing too hard with the rolling pin. 

If the clay is sticking to the rolling pin, it is too moist.  Work it into a piece of canvas to get some of the moisture out.  Also make sure that no clay has accumulated on the rolling pin before you begin.  Your clay slab will stick to these pieces. 

When constructing slabs, it is best to have them slightly dry because moist slabs will not hold up and will wobble and droop.  It is also best to join clay that is the same consistency to prevent warping and cracking as they dry at different rates.

When joining slabs, it is advisable to score the surfaces of the pieces to be joined.  This means to make some scratches in them to roughen them up, making the surfaces stick together more readily.

Once the main body of the slab structure is assembled, it can be paddled, shaped, cut into, twisted, or otherwise formed into the final concept.  Other appendages, handles, spouts, decorative clay forms, wads of clay, coils, decorations and textures can then be added if desired. 

Creating textures

Certain textures are best applied when the clay is in the soft, plastic state.  For example, you can pinch or “flute” the edges of a piece.  You could also pinch small parts outward over a large area to create a scaly appearance. 

Impressed designs can be made by pressing textured objects into the clay.  Objects such as pencil erasers, forks, shells, bottle caps, fabrics, etc. can be used to create interesting textures and patterns.  The texture should be applied when the clay is soft enough to take an imprint, yet not so soft as to stick to the texturing device. 

Other interesting textures can be created by carving into leather-hard clay.  It is important that the clay has dried partially and is no longer pliable.  This way, you can make deep cuts and even holes in the surface that won’t affect the stability of the piece.  You can use a paperclip loop to scoop out clay and make unique textures.


The clay must dry for several days before firing in the kiln.  If it is too moist, it will explode.  The kiln heats the clay pieces to a temperature of about 1870 degrees Fahrenheit for about 3 ˝ hours.  This makes the clay durable and fuses small appendages to the main construction more permanently.  Because the molecules of clay will become more compacted, your final project will be about 90% of the size it was before it went in.  You will now be able to touch small pieces and use handles without worry of damage.


If you want your clay piece to be protected from water, you will want to apply a glaze.  This is a mixture that contains small pieces of glass that when heated, the glass crystals to melt and fuse together, forming a glassy coating.  Any depressions in the clay from the textures you created will have a deeper color because the molten glass will settle in these areas. 

You will paint 2-3 coats of it on your piece and then it will be fired again.  The color of the glaze is rarely the color it will be once it is fired.  Make sure not to paint any glaze on the bottom of your piece or you risk having it stick to the kiln shelf.  The only way of removal is destroying the piece. 

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