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clay
by Madison Byrd
Physical Geology
Fall 2013
          
  
 

Clay to Pottery


Pottery is a great form of art and is useful in everyday life. From teapots to floor tiles clay is used every day around the world. Some works can date back centuries. These works are now collected or on display at museums. 
 

         
 

Timeline of Ceramic and Glass Developments

 

Year

Development

24,000 B.C.

Ceramic figurines used for ceremonial purposes

14,000 B.C.

First tiles made in Mesopotamia and India

9000-10,000 B.C.

Pottery making begins

5000-8000 B.C.

Glazes discovered in Egypt

1500 B.C.

Glass objects first made

1550 A.D.

Synthetic refractories (temperature resistant) for furnaces used to make steel, glass, ceramics, cement

Mid 1800′s

Porcelain electrical insulation
Incandescent light bulb

1920′s

High-strength quartz-enriched porcelain for insulators
Alumina spark plugs
Glass windows for automobiles

1940′s

Capacitors and magnetic ferrites

1960′s

Alumina insulators for voltages over 220 kV
Application of carbides and nitrides

1970′s

Introduction of high-performance cellular ceramic substrates for catalytic converters and particulate filters for diesel engines

1980′s

High temperature superconductors

 

Kinds of Clay

1. Earthenware is a low-fire clay which is fired in the kiln at a temperature range of 1700 to 2100F (9261150C).

2. Stoneware is a durable clay which is fired in the kiln at temperatures between 2100 and 2300F (12051260C).

3. Kaolin is a high-fire clay which is fired in the kiln at temperatures between 2335 to 2550F (1280-1400C)
 

The Firing Process

After youre done making your ceramic piece you let it slowly dry. If you hurry this process your piece could crack or break. When the piece is dry it will go in the kiln at whatever temperature the clay needs to be fired at. Then it will become bisque ware which is porous. Liquid and air can still pass through the clay. The clay will stay together but not hold your soup or drink. Glazing is the next step in the process it is a mixture of minerals that most potters keep secret. Glaze cannot get on any part of the piece that will be touching the kiln shelf or the glaze will melt to the shelf. Also the glaze cannot be on too think or too thin. Once the piece is glazed it will be put in the kiln again to melt the glaze which is like glass. When the piece has cooled you will see the true color of the glaze and its done.

Glazes

            Glazes are a vitreous substance fused on to the surface of pottery to form a hard, impervious decorative coating. Some glazes food safe which means you can use them with drink ware, plats, and bowls. Some glazes are not these may contain lead or other toxic minerals. This kind of glaze will be used for tiles, art, and vases. These glazes are layered which you can use to get a cool effect. It almost like painting with water colors because glazes move as they melt onto the piece. The only difference is that you will not know how the glaze will turn out till after your piece is out of the kiln. My teacher always said never think the color will look one way because it never will. 
 


 

Kilns

Kilns are a furnace or oven for burning, baking, drying, or firing pottery. In the picture below are some kilns of different shapes and sizes. All of these kilns are electric which the most efficient way to fire clay now. A studio should have one to four different size and shaped kilns. The reason for this is if you have a huge vase you will require a deeper kiln. If a studio had a lot of platters being made you would need a big wide kiln. If you have a home studio a small to mid-size kiln would be best for you so youre not wasting a huge kiln to fire seven items at a time.


 

These are some of my works I hand built and slab built all of them. There are five different glazes being used but there is a variety of shades and how they look on the clay. Glaze color can affected by the clay color, the thickness of the clay, and the height of your piece.


Different Ways to build

There are many different ways to make different pieces from slab building, hand building, coil building, and throwing on the wheel.
 

Slab building is when you use a slab roller to roll clay in to a thin sheet and cut out a shape. In my picture the owls faces are cut out of a slab and scratched and slipped on to the owl body. The log is made out of a slab but instead of leaving it flat I laded it on a cylinder and drew lines on it to make it look like a log.
 

Hand building is how I made the owl bodies I rolled a ball of clay in my hands and made the shape I wanted then I used a tool to take the clay from the inside of the owl so the owl is hollow. If I did not hollow them out they would have exploded in the kiln.
 

Coil building is when you make a long coil and scratch and slip it to another coil to make something. The mushrooms in my picture are made this way. Coil building is tricky the taller or bigger you go. If you build too much before the bottom has set the whole thing could collapse onto its self. You must coil build in steps to prevent that from happening.
 

Throwing on the wheel is a whole other thing I find it very hard to do. First you must center the clay on the wheel and then you have to open the clay into the shape you desire. Then come drying till leather hard which is till the clay can hold its shape but still be soft enough to alter. Then you trim your vessel so the bottom is smooth. Then dry it till it ready to be bisque.     

 

Work Cited

http://www.amaco.com/ceramic-installations/alan-reinhardt-ceramic-installations/

http://ceramics.org/learn-about-ceramics/history-of-ceramics

http://ceramics.org/learn-about-ceramics/history-of-ceramics

http://www.howtomakepottery.com/

http://www.infoplease.com/spot/clay.html

http://www.sheffield-pottery.com/Skutt-Kilns-s/69.htm