A throwing body needs to be plastic enough to centre without fighting, strong enough to stand up when it is pulled thin, and fine enough not to shred your fingertips over an hour. Plenty of clays are excellent for hand building and unpleasant on the wheel, and the difference is mostly grog.
Plasticity is what makes a body throw
Plasticity is the clay's willingness to be moved and to stay where it is put, and it comes largely from fine particle size and from ball clay in the recipe. A plastic body centres with less force, holds a wall as it is pulled and forgives a hesitation. A short body, one with poor plasticity, tears at the rim and collapses under an uneven pull, which most beginners read as their own failure.
Grog: some helps, a lot hurts
A little grog gives a throwing body backbone and helps a wide form stand. A lot makes the clay abrasive enough to remove skin over a long session and prevents crisp detail. Most throwers settle on a smooth or lightly grogged body for the wheel and keep a heavily grogged clay for hand building, rather than trying to find one clay that does both.
What to buy first
A smooth or lightly grogged buff or white stoneware, in a 12.5 kg bag, matched to whatever kiln will fire it. That covers mugs, bowls, jugs and plates, throws forgivingly, costs among the least per kilogram of anything on a price list, and is what most studios teach on. Porcelain and heavily grogged bodies are worth trying afterwards, not first.
Preparation matters as much as the body
Clay straight from a sealed bag is de-aired and ready. Clay that has been reclaimed, stiffened or partly dried needs wedging, and an unwedged lump with hard and soft areas will not centre no matter how good the body is. If the wheel seems impossible on a particular day, the clay is worth checking before the technique.
Questions people ask about pottery wheel
What clay is best for the pottery wheel?
A smooth or lightly grogged stoneware. It is plastic, forgiving, inexpensive per kilogram and covers almost all functional work.
Can you throw grogged clay?
Lightly grogged, easily and usefully. Heavily grogged bodies are abrasive on the hands and better suited to hand building.
How much clay does a beginner need?
More than expected, because most early pots go back in the reclaim bucket. A 12.5 kg bag is a sensible first purchase and reclaim makes it last.