Intro to Clay
Where does this stuff come from?
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What is Ceramics?
What is Ceramics?
Ceramics is the art of making objects out of Clay
-Objects or sculptures are built out of clay and then fired in a kiln, a special ceramics oven. Then the object can be glazed and fired again to add color or gloss to the piece.
Where does clay come from?
Where does clay come from?
Clay is a NATURAL RESOURCE, which means it is not made by humans. Rather clay comes from the earth. Clay is in fact all around us, it is part of the earth’s crust and the surface on which we live. It is usually found in little pockets that appear a couple of feet below the ground. Clay is made from rocks, minerals and water found in the earth by rivers and streams.
How is clay made ?
How is clay made ?
Clay is originally formed from GRANITE ROCK, which makes up a large area of the earth’s crust.
Clay is originally formed from GRANITE ROCK, which makes up a large area of the earth’s crust.
Over millions of years of weathering, (through coming into contact with SUNLIGHT, RAIN and ICE) GRANITE ROCKS have gone through a physical change, being broken down into smaller and smaller particles. It is this process that transforms granite rock into clay. Clay is moved and carried around by flowing water, usually settling in the side of riverbeds.
Over millions of years of weathering, (through coming into contact with SUNLIGHT, RAIN and ICE) GRANITE ROCKS have gone through a physical change, being broken down into smaller and smaller particles. It is this process that transforms granite rock into clay. Clay is moved and carried around by flowing water, usually settling in the side of riverbeds.
For what purpose have humans used clay?
For what purpose have humans used clay?
BECAUSE CLAY IS ONE OF THE WORLDS GREAT NATURAL RESOURCES, it has been used by humans for longer and for more reasons than any other material. We know that for at least nine thousand years, humans have used clay to make bricks. Bricks which have been then placed together to form simple shelters and houses. Today clay is still an important material, being used for hundreds of purposes.
These purposes range from:
1) ornaments, 2) plates, cups, tea pots,
3) washbasins, 4) insulation for electrical cables and power-lines, 5) and even the tiles on the space shuttle. (This is because they are great for reflecting
and absorbing heat).
Types of clay!
Types of clay!
There are basically two types of clay, Earthware and Stoneware clay. In this Clay studio we will be using an Earthware clay which means that its a low fire clay.
As you will soon be aware, it is a very plastic like material, being able to be worked into various shapes and forms.
-Clay comes in a variety of colors. Ranging from RED to YELLOW and BLACK to GREY. The reason for these different colors is due to the fact that they have been moved around. What happens is that on their journey they have come into contact and mixed with different minerals. These different minerals have mixed with the clay and are responsible for producing the different colors.
Clay properties: Working with clay.
Clay properties: Working with clay.
Plasticity= of clay means the wetness of the clay
Shrinkage= clay shrinks as it dries so it is very important to let it dry slowly if not it will crack.
Texture= of clay body can range from course to smooth. T
Moisture= All clay contains water. Clay will be begin to dehydrate when exposed to air. You will occasionally need to rehydrate your clay to keep it moist. However to much water, the clay will lose its strength and become too plastic. You want to spray it with a water bottle or a dampen sponge.
Preparing the Clay= all clay needs to be de-aired before you begin by WEDGING. WEDGING eliminates air bubbles and keeps the internal structure of clay more cohesive and consistent.
Clay Safety= capture little clay piece with a wet sponge, don't drop them on the floor because they will be crushed and then tiny clay particles will be floating in the air that you are breathing and that is not SAFE to be b
Seven Stages of Clay
Seven Stages of Clay
Wet
Leather-hard
Greenware
First Fire
Bisque
Glazed
Second Fire
Wet Clay
Wet Clay
What do we notice about clay at this stage?
At this stage clay is soft and flexible because it is 75% percent water
It is somewhat forgiving at this stage
It is at the “workable” consistency for building slabs, coils, and throwing
Clay can be recycled at this stage
Leather-hard Clay
Leather-hard Clay
After clay has been worked with and exposed to the air the water begins to evaporate, now it is only 50 - 30% water. Making it somewhat stiffer.
This is the perfect stage for building and carving in detail to the surface. The clay has structure and strength but it still workable for change. We LOVE this stage and want our project to stay in this stage until we are finished working on it.
To keep your clay project in this stage you must wrap it with a plastic bag and sometimes mist it with water.
Clay can be recycled at this stage
Greenware Clay
Greenware Clay
Greenware clay is clay that has been exposed to the air long enough for all the water to evaporate from the project. It is made of 0% water. In other words, its DRY and very FRAGILE!
Once you have completed your project you will leave it unwrapped so it can enter the greenware stage. It can take up to two weeks for your project to be completely dried.
Clay at this stage will hold its shape but it is very fragile, if it breaks at this stage there is no way of fixing it.
what you have made is not just clay anymore it is now a ceramic piece.
This is the last stage in which we can recycle the clay.
First Fire
First Fire
Once clay has completely dried out and has entered the greenware stage
Greenware projects will be put in the kiln and fired.
A kiln is a ceramics oven
Firing is when the temperature inside the oven is brought up to about 1900 degrees (almost 4x hotter then a kitchen oven). This is a low fire temperature; high fire is about 2400 degrees
this first firing processes changes the clay to Bisque clay.
Bisque clay
Bisque clay
Clay that has been through one firing in the kiln is called bisqued clay.
this is clay that is permanently hard.There is no going back to workable clay after it had been bisque.
the clay is now strong but remember its still ceramic be careful!
Glazing
Glazing
Glazing is when you paint a thin layer of minerals and glass onto a bisque ceramic piece. This will give your piece color and gloss.
Glazes look different when they come out of the jar than they do after the second fire. Look at the glaze chart to know what color it will be.
You can glaze the inside and outside of project but not the bottom. If glazes are on the bottoms they melt and glue themselves to the kiln shelf.
Second Fire
Second Fire
After the glaze is painted on your ceramic piece it will go back into the kiln for a second fire
the kiln heats up to only 1700 degrees this time
This changes the glazed to there final look giving your ceramic project the final touch.
Joining Clay Parts Together
Joining Clay Parts Together
They call it “Slip and Score” or “Scratch and Attach” you must SCRATCH AND ATTACH all clay parts!
Slip is a liquid clay used in joining clay pieces together. Its like clay GLUE. It has the consistency of yogurt. You can put your tiny scrapes of clay into your slip cup
Make sure to score both pieces of clay
Clay Building Techniques
Clay Building Techniques
There are different techniques you can use when building with clay and many times you will use them together to build your projects.
Pinch Pot Method
Coil Building
Slab Building
Throwing/Pottery Wheel
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