Art Clay 650, with its low firing temperature, can be combined with porcelain, polymer clay, glass, glass beads, and dichroic glass to create beautiful effects.

Clay is formed naturally over millions of years as rocks break up into minute particles. It consists of hydrous aluminium silicates, and other compounds such as iron oxides, quartz, mica, and feldspar.

Clay is often divided into three main categories: earthenware, stoneware, and porcelain. Generally, it needs to be fired for several hours, although impurities affect the time, temperature, colour, and shrinkage.

Earthenware is normally red, beige, or white. It has the lowest firing temperature of the three, usually about 1150°C. It's slightly porous, and stains and chips easily, so it's often glazed to protect the surface. Its porosity means it's good for making planters and oven steamers, but not good for pitchers or vases.

Porcelain is composed of kaolin, known as china clay, ahown in the photo. Kaolin doesn't melt until 1800°C, so other compounds are usually added so it can be fired between 1250°C and 1400°C. For example, bone china is made by adding bone ash to the clay.
Porcelain is known for its whiteness, hardness, smoothness, durability, and translucency. When tapped, it makes a distinctive ring, ping, or ming.

Stoneware is normally red-brown, beige, or grey. It's usually fired between 1150°C and 1300°C. It's hard, durable, and resists thermal shock. Glazes bond well, so it can be made waterproof.

Polymer clay is a man-made material: tiny particles of polyvinyl chloride mixed with plasticizers and pigments. When it's baked, at around 125°C, the particles fuse and the clay hardens.

Raku was originally a Japanese technique, but it's now become an internationally popular way to make decorative ware. Basically, you start with a piece bisque-fired to about 950°C, and then glaze it. It's removed from the kiln when red-hot, and put straight into a container of combustible material.

The flames, reducing atmosphere, and mix of chemicals stain the clay. When the piece is removed and quenched in cold water, interesting colours and shades remain: often unpredictable.

The metric system, used in the EU and most other countries, uses centigrade. The US and a few other countries use fahrenheit. There are simple ways of converting:

centigrade = (fahrenheit - 32) divided by 9 then multiplied by 5

fahrenheit = (centigrade divided by 5 then multiplied by 9) + 32

Using the centigrade scale, water freezes at 0°C and boils at 100°C. Using the fahrenheit scale, water freezes at 32°F and boils at 212°F.