At the Wheel
Throwing a Bowl: The Sequence of Moves
Throwing looks like sculpture and is closer to a sequence of fixed operations. Each step exists because the step after it will not work otherwise.
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.
Wedging, before the wheel is switched on
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.
The reason is mechanical rather than aesthetic. A trapped air bubble in a spinning wall becomes a soft spot, and the wall thins there first and tears. A wet streak behaves differently from the clay around it and pulls the form off true. Wedging is the least visible stage of the whole process and the one most likely to be blamed for a failure three steps later.
Centring
The lump is thrown down onto the wheel head and then forced into a shape that is symmetrical about the axis of rotation. A centred lump does not wobble, and a hand held steadily against it feels no rise and fall at all.
Centring is done with braced arms, not with hand strength. The heel of one hand pushes inward while the other presses down from above, and the arms are locked against the body or the wheel frame so that the pressure is constant. The wheel does the work; the potter supplies a fixed obstacle for the clay to turn against. Water is used sparingly, because clay that gets too wet loses the strength it needs to stand later.
Nothing that follows can correct an uncentred lump. Every subsequent move is made relative to an axis, and if the axis is wrong the pot is wrong.
Opening
With the lump centred, both thumbs or a braced set of fingers press down into the middle and stop short of the wheel head, leaving a floor. The floor thickness is set here and cannot be increased afterward. A common measure is to leave roughly the thickness of a finger, then check it with a needle tool pushed through until it touches the wheel and marked with a thumbnail.
The opening is then widened outward, which begins to establish the diameter. For a bowl this is done generously, because a bowl's form is opened wide and lifted shallow rather than raised tall.
Pulling the wall
The wall is raised by compressing a ring of clay between a finger inside and a knuckle outside and moving that pressure slowly upward while the wheel turns. The clay does not stretch. It is displaced from the thick base and carried upward, which is why the first pull starts hard against the floor.
Three or four pulls are typical. Each one is slower than it looks, because the wall has to complete several rotations under the pressure point for the thinning to be even. Rushing produces a spiral of thick and thin bands that will show as a wobble in the rim and a weak point in the wall.
The wall is kept slightly thicker at the base than at the rim throughout. That taper is structural: the base carries the weight of everything above it.
Shaping the curve
Only when the wall is at full height does the bowl become a bowl. The curve is opened from the inside, with the outside hand supporting rather than pushing, and it is developed from the bottom of the curve upward in a single continuous move. A bowl shaped in separate patches shows the joins as flat facets under a glaze.
The rim is compressed at the end with a finger and thumb, or with a piece of soft leather held loosely around it. Compression aligns the clay particles at the edge and is the main defence against the rim cracking during drying.
Cutting off and turning
A wire is pulled under the base and the piece is set aside to stiffen. When it has reached leather hardness, firm enough to handle but still damp, it goes back on the wheel upside down and the foot is turned: excess clay is cut away from the base with a loop tool, a foot ring is defined, and the underside is refined.
Turning is where the weight of the finished bowl is decided. A form that felt right when wet is usually far too heavy at the base, and a good deal of clay comes off at this stage. It is also where the pot is signed, because the bare foot is the one surface that will not be covered by glaze.
Then a long wait
Throwing a bowl takes a few minutes. Getting it to a finished pot takes weeks: slow, even drying under plastic so that rim and base lose water at similar rates, a bisque firing, glazing, and a second firing. The wheel is the fast part and the least likely place for the piece to be lost.