Why Coil Building Still Rewards the Patient Maker

Coil building is how potters made vessels for thousands of years before the wheel came along, and it remains the most flexible way to make a pot. You can build wide, oval, lopsided or sculptural forms that a wheel would simply refuse to throw. It is also the technique that teaches you most about clay: how it behaves when wet, how it stiffens, and when it is ready to take more weight. The trade-off is patience. Rush a coil pot and it will slump, crack along the joins, or fold under its own mass. Work steadily and it will outlast most thrown pieces.

Setting Up: Clay, Tools and a Stable Base

Before you roll a single coil, sort out your materials. Any plastic stoneware or earthenware body will coil well. Heavily grogged clay is more forgiving for beginners because the grog opens up the body and reduces cracking, though it is rougher on the hands. Avoid clay that has been sitting out and stiffening unevenly, as it rolls into coils that tear at the edges.

• A clean, non-absorbent board or bat to work on — MDF, plywood or a canvas-covered board
• A rolling pin, or simply the flat of your hand
• A needle tool or fork for scoring
• A small pot of slip, mixed to the consistency of double cream
• A wooden modelling tool or rib for blending
• Plastic sheeting or a carrier bag to wrap work in progress
• A banding wheel or turntable, which saves endless walking around the pot

Wedge your clay first. Even a minute or two of spiral wedging removes air pockets and evens out moisture, and it is the difference between coils that hold together and coils that split at the join.

Rolling Coils That Are Actually Even

Rolling an even coil is a knack, and the mistake almost everyone makes is pressing too hard in the middle. Start with a lump about the size of a large walnut. Roll it between your palms on the board with light, even pressure, moving your hands outward as the coil lengthens. Let the coil grow longer before it grows thinner. If it tapers, stop and begin again from the middle.

• Keep the thickness consistent — roughly 1cm for a medium pot, 1.5cm for a large one
• Roll only as much as you can join in one go, as a coil left sitting dries out
• If the coil cracks, it is too dry: wrap it in a damp cloth for ten minutes
• If it sticks to the board, it is too wet: let it firm up briefly

Long coils are easier to handle if you support them along their length with your fingers rather than lifting them by one end.

Score, Slip and Join Every Coil Properly

This is where coil pots succeed or fail. Never rely on pressure alone to hold a coil in place. Score the top edge of the pot and the underside of the coil with a needle tool or fork — shallow crosshatching is plenty. Paint slip onto both scored surfaces with a brush or your fingertip. Press the coil down firmly, then blend it.

Blend on the outside by pushing the clay downward with your thumb, and on the inside with your fingers or a wooden tool. Every coil needs blending inside and outside, unless you want the coils to remain visible as a deliberate decorative feature. Even then, the joint at the base of each coil must be sound, or the wall will harbour weak points that open up later in the kiln.

Building Upward Without Slumping

Slumping happens when wet clay cannot carry the weight above it. Three rules will see you right.

• Work in stages. Add three or four coils, then stop and let the pot firm up — thirty to sixty minutes under plastic, until leather hard, is usually enough
• Keep the lower coils stiffer than the upper ones, and soften the rim area slightly as you build
• Support the shape from inside. A cardboard cylinder, a rolled newspaper tube or a bag of rice keeps the walls from bulging inward as you press

Rotate the pot regularly on a banding wheel so you see it from every angle and keep the rim level. Pinch the rim between thumb and forefinger at the end of each session to even it out. Remember, too, that clay shrinks as it dries, so walls that are too thin at the base will crack before the pot is even finished.

Refining the Surface and Drying Before Firing

Once the pot is built to height, tidy the surface with a rib while the clay is still soft enough to move. Remove any finger marks you do not want, tidy the rim, and consider adding a foot ring or a spout while the clay is at the leather-hard stage, when it holds its shape but still takes a join.

Drying is the step that undoes more coil pots than building ever does. Cover the finished piece loosely with plastic and let it dry slowly over several days, opening the covering a little more each time. Uneven drying — a draughty shelf, a radiator, a sunny windowsill — causes cracks and warping. When the pot is bone dry and cool to the touch, it is ready for a bisque firing. Uneven wall thickness and trapped moisture are the usual causes of blowouts in the kiln, so be honest with yourself about whether the base is as dry as the rim.

Finally, date your pots and note the clay body you used alongside the coil thickness. Coil building rewards repetition more than talent, and a written record is how you turn a decent first pot into a genuinely good tenth one.