A small clay tray is an excellent use for a slab: it can hold keys, a spoon, a bar of soap, or the loose objects that gather beside a bed. Yet its apparent simplicity can be misleading. A broad, thin surface remembers every uneven stretch and every hurried stage of drying. The result may be a tray that twists at the corners, cracks at the rim, or rocks on the table.
The remedy is not elaborate equipment. It is a sequence of modest attentions: use clay of even thickness, compress both faces of the slab, let a shallow mould establish the form, and slow the drying enough that the rim and centre lose moisture together.
This project makes a shallow catchall tray with a soft oval or rectangular outline. The mould need not be a purchased form. A smooth bisque hump mould, a plaster mould, or a gently rounded, non-porous household form covered in thin plastic can work. Choose something low and broad rather than steep-sided; clay settles more willingly over a gradual curve.
What you will need
- Mid-fire stoneware clay, reasonably soft but not sticky
- Canvas, sturdy fabric, or a smooth work surface
- Rolling pin and two rolling guides of equal thickness
- A plaster or bisque draped mould, or a smooth shallow form covered with plastic
- Metal rib or firm rubber rib
- Needle tool or craft knife
- Soft sponge
- A flexible plastic rib, card template, or paper pattern
- Plastic sheeting and a board for drying
- Underglaze, glaze, or both, if desired
For a tray about 18 to 22 cm across, begin with a slab roughly 6 mm thick. This is substantial enough for ordinary handling while still allowing the clay to settle over a shallow mould. Very thin slabs dry quickly and show every small distortion. Much thicker ones can feel heavy and may be slow to dry through at the centre.
Prepare the mould and the clay
Set the mould on a firm board before you begin. If it is plaster or bisque, its absorbency can help the clay firm gradually, but do not leave the slab on it so long that the underside stiffens while the exposed rim remains wet. If the mould is glass, metal, plastic, or a household object, cover it smoothly with thin plastic so the clay releases without pulling.
Wedge the clay only as much as needed to make it uniform and free of obvious joins. Form it into a thick puck rather than a long coil. A compact starting shape rolls out more evenly.
Lay the clay between the rolling guides on canvas or fabric. Roll from the centre outward, turning the slab occasionally rather than repeatedly dragging it in one direction. Lift or sandwich the slab on boards when moving it, especially while it is soft. A wet slab stretched by one edge may appear sound at first, then curve as it dries.
After rolling, compress the upper face with a metal rib. Use overlapping passes, firm enough to smooth and align the surface but not so hard that the clay is thinned at the edges. Turn the slab over with the support of a second board or canvas and compress the other face as well. This simple work is especially worthwhile on flat forms, where uneven compression often becomes uneven movement later.
Photo by Roman Kraft on Unsplash.
Make the tray blank
Decide on the final outline before cutting. An oval is forgiving and has no sharp corners to lift. A rounded rectangle is equally useful, but keep its corners generous. Tight inside curves and pointed corners dry at different rates from the rest of the piece and are more likely to cause trouble.
Make a paper template, or cut by eye with a needle tool. For a tray around 20 cm long, cut the slab blank about 2 to 3 cm larger all around than the upper surface of the mould. That extra clay becomes the shallow rim.
Avoid sawing back and forth through the clay with the needle. One calm, continuous cut gives a cleaner edge. Remove excess clay and cover it for another project.
Before draping, inspect both faces of the blank. If one side has become much wetter through sponging or handling, leave the slab uncovered for a few minutes until the surface sheen has faded. It should bend without cracking, but it should not slump under its own weight.
Form the tray over the mould
Place the mould on a board and centre the slab over it. Support the slab with both hands or with a sheet of fabric beneath it as you lift. Lower it gently rather than pulling the middle downward. Let gravity begin the curve.
With open fingers, ease the clay onto the mould from the centre toward the rim. Do not stretch the slab to make it conform. If it does not settle into place, pause and allow it to firm slightly rather than forcing it. Stretching wet clay is one of the quiet causes of later warping.
Shape the rim with a restrained hand. For a shallow catchall, the edge only needs to rise around 1.5 to 3 cm. Press the perimeter gently toward the mould, then refine it with a soft sponge or flexible rib. The aim is an even, unbroken line, not a sharply pinched lip.
If the rim has become thin from handling, strengthen it now. Rather than adding a bulky coil, compress the edge between finger and thumb with light, repeated pressure. This makes the thickness more consistent and rounds the vulnerable cut edge.
Leave the tray on its mould until it is firm enough to hold its own curve. The exact time depends on the clay, room, and mould, so judge the material rather than the clock. It is ready to remove when the surface no longer feels tacky and the edge can be touched without leaving a fingerprint.
Photo by Anne Nygård on Unsplash.
Refine the underside and foot
Lift the tray off the mould with both hands, or invert the board and mould together so that the tray is not bent by a single point of contact. Set it right-side up on a padded surface or a small ring of soft foam while you inspect the underside.
A tray may be left with a plain, gently curved bottom, but a modest foot gives it a more deliberate finish and keeps the glazed surface slightly raised from the table. There are two simple approaches.
A carved foot
When the clay is leather hard, turn the tray over on foam. Use a loop tool or trimming tool to remove a shallow channel near the outer underside, leaving a broad raised area inside it. Keep the foot wide and low. A narrow, tall foot concentrates stress and makes a lightweight tray more likely to wobble.
An applied foot
Roll a short, even coil and shape it into an oval or rounded rectangle slightly inside the tray’s perimeter. Score and slip both surfaces, press the coil on evenly, then blend its outer edge into the underside. Let the join stiffen under loose plastic before moving the tray again.
For a first project, the carved foot is often the calmer choice because it introduces no additional join. Whichever method you choose, test the tray on a truly flat board at leather hard stage. If it rocks, correct it then by gently compressing the high area or refining the foot. Do not wait until bisque firing, when adjustment is no longer possible.
Smooth any roughness with a barely damp sponge. Excess water at this stage can soften the rim and undo the crisp, even shape you have established.
Dry it slowly and evenly
Drying deserves as much care as forming. The raised rim has more exposed surface than the centre, so it naturally wants to dry first. If it races ahead, the centre is pulled against a stiffening perimeter and cracking or distortion can follow.
Place the tray on a dry board, ideally on a surface that allows some air to reach beneath it. Cover it loosely with plastic. For the first day, keep the plastic fairly close but not sealed tightly against the clay. Then uncover it in stages: open one side, then widen the opening as the clay becomes firm. Turn the tray occasionally only when it is strong enough to handle without flexing.
If the edge seems to be drying much faster than the centre, wrap a strip of plastic around the rim or rest loose plastic over the outer edge. The purpose is not to keep the tray wet indefinitely, but to slow the parts that are running ahead.
Do not dry the tray in direct sun, near a heater, or in a strong draft. Slow, even loss of moisture is more useful than speed. Let it become completely dry before bisque firing; a cool feeling against the cheek usually means there is still moisture within.
Photo by Jonathan Cosens Photography on Unsplash.
Bisque, colour, and glaze
Bisque fire according to the requirements of your clay body and kiln. Once bisque fired, smooth any small sharp points with fine abrasive material used carefully and with appropriate dust control. Wipe the piece clean before glazing.
For a tray intended for keys, jewellery, or dry objects, underglaze beneath a clear glaze gives a durable, straightforward finish. A single satin or gloss glaze can be equally suitable. Choose a glaze known to mature at the clay body’s firing range.
A very glossy glaze may show pooled thickness in the lowest part of the tray. Apply it evenly and avoid an overly heavy coat at the interior centre. If you use an unglazed foot, wipe glaze well clear of its contact surface so the tray does not adhere to the kiln shelf. A stable glaze that does not run is generally the better choice for this small, flat form.
For a soap dish or a tray that will meet regular moisture, consider adding a few shallow drainage grooves before bisque firing, or reserve the form for dry use. A plain catchall is simpler and more versatile.
Common troubles and their likely causes
The tray has lifted or twisted at one corner
This often begins with an uneven slab, a slab stretched while being moved, or one side drying more quickly than the other. Use boards or fabric to support soft clay, compress both faces, and dry under loose plastic with attention to the exposed rim.
The rim has cracked
The edge may have been left thinner than the centre, or it may have dried too quickly. Compress and round the cut edge while the clay is soft, then shelter the rim during the early drying stage.
The tray rocks after firing
A rocking tray may have dried on an uneven surface, warped during handling, or had an irregular foot. Check it on a flat board at leather hard stage, when small corrections remain possible. Keep any foot broad and even.
The tray has a rough or heavy-looking edge
This is usually a finishing matter rather than a structural one. Refine the rim in several light passes with a sponge or flexible rib. Trying to solve it with one wet, forceful pass can leave the edge thin and weak.
A well-made slab-built ceramic tray does not need ornament to be satisfying. Its usefulness lies in its level base, gentle rim, and the small evidence of the hand in its softened line. Let the mould do the quiet structural work, and give the clay enough time to settle into the shape.