I majored in journalism in university but I minored in art. (Well, actually I minored in Dungeons and Dragons, but the university refused to give me any credits for it. Go figure.)

Of all my art classes, my favorite was pottery. I loved making pots, but as a certain hideously ugly four-kilogram cream pitcher can attest, I was never very good at it.

Fortunately, over the years, other people have been very good at it indeed. In fact, pottery is one of the oldest of human crafts. Its other name, "ceramics," comes from the Greek word "keramos," or clay--and indeed, pottery begins with clay.

Clay is made up of fine, plate-like crystals of (if you must know) hydrated aluminosilicates, about 1 to 10 microns (a micron is 1/1000th of a millimetre) in length. A thin film of water binds these crystals together, and the lubrication of the water, plus their plate-like shape, enables them to slide easily over one another.

Because of that, as some ancient unsung hero discovered, clay can be shaped in many ways. It can be flattened and pressed against the walls of a mold (or liquefied and poured into one); it can be rolled into coils from which a pot can then be built up; it can be pinched into shape; or it can be shaped into beautifully symmetrical pots on a flat, spinning wheel, as some other unsung hero discovered around the fourth millennium B.C.

No matter how it's formed, a wet clay bowl isn't much good for carrying things in, but at some point some other genius decided to try to harden a bowl by sticking it in the fire. The rest, as they say, is history.

If enough heat is applied to clay, its crystals begin to melt together to form a single, coherent mass--a process called sintering. At relatively low temperatures (900 to 1200 degrees Celsius) relatively large, continuous openings remain in this material. That produces the porous pottery called earthenware, and it's still the most common kind.

At temperatures between 1200 and 1280 degrees, clay becomes stoneware: much more durable and, because the continued heating causes the pores to close off, waterproof. The ancient Chinese made stoneware but it didn't become known in northern Europe until after the Renaissance.

Finally, there's porcelain, fired at 1280 to 1400 degrees. The Chinese were also the first to make this hard, glassy, white form of pottery, which is why it's still commonly called "China." Porcelain begins with a mixture of a pure, white clay called "kaolin" (which is actually decomposed granite), feldspar and silica sand. During firing, the feldspar melts and coats the clay crystals, which turn into fine, needle-shaped crystals called mullite. Meanwhile, the grains of sand partially dissolve in the feldspar. When all this cools, you get the stuff from which tea cups are made.

Porcelain is glassy and waterproof on its own, but earthenware has to be "glazed" if it's going to hold liquid. Glazing was always my favorite part of pottery class, probably because it was more like chemistry than art: you mixed a variety of exotic ingredients in an attempt to create a particular effect. (It also didn't involve manual dexterity, unlike, alas, the making of pottery itself.)

Glazes basically consist of powdered glass, with materials such as lead, soda or tin added to lower the glass's melting point and metal oxides added for color. Before being applied, glazes look like thick soup; afterward, they form a glassy layer over the surface of the pottery. The color of that layer depends on the ingredients used. Lead and alkaline glazes tend to be transparent; tin glazes are opaque. Copper oxide will turn a lead glaze green and an alkaline glaze turquoise in a normal, well-ventilated kiln; in an oxygen-starved kiln, it can produce other colors. In fact, variations in firing can produce so many variations in the glaze that it's very difficult to create a glaze that does just what you want--although fortunately, one of the great things about making pottery is that unforeseen effects can look even better than what you had in mind.

Ceramics continue to be used for plates and bowls and pots, many, as you'll see at Regina's annual craft festival Baazart (coming up in the next couple of week's), of surpassing loveliness. It's odd to think that such an ancient craft has also given us the tiles that protect the space shuttle from the heat of re-entry and replacement parts for our bones and teeth. In the near future we may even see an all-ceramic engine in cars.

Considering my eight-pound cream pitcher, though, it'd probably be best if they don't ask me to build it.