Types of Clay for Pottery: Clay Body Selector

How the clay body selector works

The selector first checks firing, then scores everything else. A clay is ruled out if it can’t mature in the firing range you chose, or in the highest range your kiln access reaches, because a body fired too low stays weak and porous and one fired too hot can slump, bloat or melt onto the shelf.

Earthenware needs a low firing. Stoneware, porcelain and bone china need mid or high. If you pick a firing service, the tool assumes low and mid-fire are available, which is what most community studios offer. If you choose a range your kiln can’t reach, it says so and ranks for your kiln’s top range instead.

Every clay that’s still in then collects points from your other four answers, using the table below. The scores run from minus 3 (a poor match) to plus 3 (a strong one), and the clay with the highest total comes first. When two clays tie, the more forgiving one goes first, in the order earthenware, stoneware, porcelain, bone china.

“No preference”, “Either” and a flexible budget add nothing. The points are our studio judgement, not a published standard, so read the reasons as well as the totals.

The main types of clay for pottery, explained

The four types of clay for pottery are separated by firing temperature and by how dense the fired clay becomes. The lower a clay is fired, the more open and porous it stays; the higher it goes, the more it fuses into a dense, glassy body.

Earthenware is the low-fire family. Digitalfire defines it as clay fired at cone 010 to 04, and most potters glaze-fire it around cone 06 to 04, roughly 1000 to 1060 °C. It’s usually red terracotta, though white and buff earthenwares exist. It stays porous after firing, often 10% or more, so it relies on glaze to hold water and it chips more easily than higher-fired ware. In return it’s soft to work and takes bright, saturated glazes.

Stoneware is the workhorse. Fired to cone 5 or 6 (about 1222 °C) or cone 9 to 10 (about 1285 °C), it becomes dense enough for tough, everyday functional ware, with porosity of only a few percent at its rated cone. It fires buff, grey, brown or off-white and is usually the most forgiving to throw and hand build, especially with grog in it.

Porcelain is the refined white body. It’s fired to cone 6 or cone 10, gets very close to zero absorption and can be translucent where it’s thin. Digitalfire notes it’s less plastic than stoneware and earthenware, more brittle at leather hard and more prone to warping, because it’s fired close to its melting point. Bone china is a cousin made with bone ash for extreme whiteness and translucency. It’s very short, almost always slip cast in moulds, and fired on specialist schedules.

Which is the best clay for beginners?

For most beginners, the best clay is a grogged mid-fire stoneware. Grog (fired clay ground into sand-sized particles) gives the clay tooth, so walls stand up on the wheel, slabs crack less and pieces dry more evenly.

That’s why teachers in most community studios start new students on a buff or speckled stoneware rated cone 5 to 6. It’s plastic enough to centre, tough enough to survive learning, and dense enough after firing to make a mug you can actually use. A smooth white stoneware is lovely for bright glazes, but without grog it’s less forgiving while it dries.

Earthenware is a fair choice if your kiln only reaches low-fire temperatures, or if you love terracotta and bright colour. Porcelain is worth trying once you can centre reliably and pull even walls, because it rewards control and punishes rushing. Bone china is a project for later, and usually one for a slip-casting course rather than the wheel.

Stoneware vs porcelain vs earthenware for functional ware

For mugs, bowls and plates used every day, stoneware or porcelain fired to its full rated cone is the safer choice, because both become dense and strong. Earthenware can be functional too, but it needs a well-fitted glaze covering every surface that touches food or drink.

The difference comes down to absorption. A well-fired stoneware or porcelain soaks up almost no water, so even an unglazed foot doesn’t wick moisture. A porous earthenware body under a crazed glaze can take on water, which weakens the piece over time and leaves cracks where food can sit. If you’re making tableware in earthenware, choose a glaze its maker rates for food contact and test it on your clay.

Strength follows the same pattern. Stoneware handles the dishwasher and knocks of daily life well. Porcelain is very hard but thinner pieces can chip at the rim, and its tendency to warp means plates and wide bowls need care in the kiln. Our pottery fault finder covers warping, crazing and the other faults that show up most in functional ware.

Match your clay to the kiln that will fire it

Buy clay rated for the cone your kiln or firing service actually fires to, because a clay is designed to mature at one temperature range. This is the step the generic guides skip, and it’s the one that ruins the most work.

Fire a cone 10 stoneware at cone 6 and it stays porous and weak, with glazes that may craze or leach. Fire an earthenware at cone 6 and it can bloat, slump or melt onto the kiln shelf, which can damage someone else’s work and the kiln. Many community studios, including our kiln firing service in Mordialloc, run separate bisque, low-fire and mid-fire loads, so tell the studio which clay you used and check that they fire to its cone.

It also pays to stick to one clay body while you learn. Mixing bodies in one piece can lead to cracks where they join, because different clays shrink by different amounts. Our clay shrinkage calculator shows how much your clay will shrink once it’s fired, and the pyrometric cone chart gives the temperature for every cone.

Common mistakes when choosing clay

The most common mistake is choosing clay by colour alone, then finding out it needs a firing you don’t have. Check the cone first, the colour second.

The second is buying porcelain for a first wheel course. It throws, but it collapses and cracks more readily, and the frustration can put people off before they’ve learned to centre. A grogged stoneware lets you build skill first. The third is assuming all clay of one type behaves the same. A red stoneware from one supplier can shrink and absorb very differently from another, so read the data sheet and run a test tile before committing to a whole set.

Finally, don’t overlook what the studio already uses. Studios choose house clays that fire well in their kilns, and the teachers know how those clays behave, which is worth a lot when you’re learning.