Pottery at Home
Stoneware and the Everyday Table
A stoneware bowl and a factory dinner plate are both fired clay, and they behave almost nothing alike once they are in daily use. The difference begins in the kiln.
Pottery at Home · About 5 minutes
A piece of handmade stoneware is an odd object to own. It is heavier than the plates sold in sets, it is rarely perfectly round, and the glaze does not repeat exactly from one pot to the next. None of that is a flaw in the work. It is a straightforward consequence of how stoneware is made and how hot it is fired, and once the reasons are clear the pots become much easier to choose and to live with.
Stoneware is not a shape or a style. It is a description of what the clay becomes at temperature. Clay bodies are classified by the heat at which they mature, and stoneware matures high, usually somewhere between 1200 and 1300 degrees Celsius. At that heat the particles in the clay begin to fuse and a portion of the body turns glassy. Potters call this vitrification. The fired result is dense, it rings when tapped, and it absorbs very little water.
Earthenware, by contrast, matures several hundred degrees lower. It stays porous. That is why an unglazed terracotta pot sweats and why an earthenware dish will eventually take up water through a crazed glaze and stay damp for days. Porcelain sits at the other end, fired as high as stoneware or higher, whiter and more translucent because of what is in the clay rather than because of any difference in principle.
The density that makes stoneware durable also makes it heavy. A thrown stoneware bowl carries more material than a pressed plate because it has to: a wall thrown on a wheel has to stand up while it is soft, and a foot ring has to carry the weight of whatever the bowl holds without flexing. Factory tableware is made by pressing a slab of clay over a mould, which permits a thinner and more even wall than a hand can pull.
Continue reading Stoneware and the Everyday Table
Clay and Body
Clay and Body · About 4 minutes
Potters talk about a clay body rather than about clay, and the phrasing is deliberate. Almost no clay used in a working pottery arrives as a single material. It is blended, and the blend is designed to do several jobs at once: hold a shape while wet, survive drying without cracking, mature at a chosen temperature, and end up a colour the glazes suit.
The component that makes clay behave like clay is a group of minerals formed by the long weathering of feldspathic rock. Their particles are flat and extremely small, and when they are wet those plates slide over one another while surface tension holds them together. That is plasticity, and it is the entire reason a lump of this material can be pulled into a wall a few millimetres thick and stay standing.
Continue reading What Makes a Clay Body Stoneware
At the Wheel
At the Wheel · About 4 minutes
Watching a bowl appear on a wheel gives a misleading impression of what is happening. It looks improvised. It is not. Throwing is an ordered sequence, and almost every difficulty a beginner meets is caused by attempting one operation before the previous one has genuinely been completed.
Clay straight from a bag contains air pockets and areas of differing water content. Wedging is the kneading process that removes both. The clay is cut, slammed and rolled repeatedly until a cut through the lump shows a uniform face with no voids.
Continue reading Throwing a Bowl: The Sequence of Moves
Glaze and Fire
Glaze and Fire · About 4 minutes
The colours on stoneware are not dyes and not pigments in the ordinary sense. They come from metal oxides dissolved or suspended in a thin layer of glass, and their appearance depends on what else is in that glass and what the kiln atmosphere was doing while it formed. This is why a potter cannot simply choose a colour the way a painter chooses a tube.
Every glaze is a balance of three things. A glass former, almost always silica, provides the glass itself. A flux lowers the melting point of the silica to something a kiln can reach. A stabiliser, usually alumina supplied by clay, stops the melted glaze from running straight off the pot.
One oxide, one recipe, two atmospheres, and the results look as though they came from unrelated glazes.
Continue reading Glaze Colour in Plain Language
Glaze and Fire
Glaze and Fire · About 4 minutes
A kiln capable of reaching stoneware temperature could get there in a few hours if it were simply switched on. Firings are not run that way. A typical schedule climbs slowly, pauses, climbs again, and then cools for as long as it took to heat. The length is not caution for its own sake; each phase is waiting for something specific to finish.
Clay that feels bone dry still holds water inside the pore structure. If the kiln is taken above the boiling point of water before that has left, the water turns to steam inside a closed body and the piece breaks, sometimes violently enough to damage its neighbours.
Continue reading Why a Kiln Firing Takes Two Days
Pottery at Home
Pottery at Home · About 4 minutes
A dense, well-fired stoneware dish is a genuinely good baking vessel. It holds heat, it releases it slowly, and it browns the underside of a gratin or a pie in a way that thin metal does not. It is also the piece of kitchenware most often broken by a habit its owner did not know was a habit.
Ceramic material expands slightly when it is heated. If one part of a dish heats much faster than another, the hot part tries to expand while the cold part holds it back, and the resulting stress has to go somewhere. In a material that cannot flex, it goes into a crack.
Continue reading Pottery That Survives the Oven
Pottery at Home
Pottery at Home · About 4 minutes
The most common mistake with handmade pottery is treating it as fragile. Fired stoneware is a hard, dense, chemically stable material; it outlasts almost everything else in a kitchen. The things that actually shorten a pot's life are specific, and none of them is ordinary use.
A vitrified, glazed stoneware piece can go in a dishwasher. The glaze is glass and is unaffected by detergent, and the body beneath absorbs almost nothing.
Continue reading Caring for Handmade Pottery at Home
Clay and Body
Clay and Body · About 4 minutes
Turn a piece of pottery over and there is usually more information on the base than on the whole of the rest of the pot. The foot is the one area that is deliberately left bare, and what is visible there is the raw fired body plus the accumulated traces of every process the piece went through.
Glaze is glass. At top temperature it is liquid, and a pot glazed all over would fuse permanently to whatever it was standing on. The bare foot is a practical necessity, not a stylistic choice, and it has the useful side effect of leaving the clay body visible for inspection.
Continue reading The Marks on the Bottom of a Pot
At the Wheel
At the Wheel · About 4 minutes
A corner of a garage, a shed or a spare room is enough room to throw pots in. The constraints that actually decide whether a small studio works are not about area. They are about where the water goes, where the dust goes, and whether the floor can carry a kiln.
Dry clay dust contains fine silica particles, and breathing it over years is a genuine occupational hazard in the trade. Everything about how a small studio is organised should follow from that.
Continue reading Setting Up a Small Home Studio