Set Up a Slaking Bucket Before You Need It

Every home studio generates the same by-product: trimmings, failed pots, slops from the wheel head, the dried-out lump you forgot to wrap. Thrown away, that is money in the bin. Reclaimed properly, it is indistinguishable from new clay and often a touch more plastic. The trick is to set up a system before the bucket overflows, so the work of recycling happens quietly in the background while you get on with making.

Keep at least two lidded buckets: one for stoneware, one for porcelain or earthenware. Mixing bodies is the fastest route to trouble — porcelain slops in a stoneware bucket will shorten the throwing range and give odd firing results. Label the buckets if you keep several. Anything contaminated with plaster, glaze, sand or metal goes in the bin, not the bucket. A fragment of plaster the size of a pea will blow a chunk out of a fired pot, and no amount of wedging will remove it.

Dry the Scraps Completely First

Counter-intuitive as it sounds, the first step in rehydrating clay is to dry it. Scraps should be bone dry before they go in the bucket — snapping rather than bending, pale rather than dark. Leather-hard lumps dropped straight into water take weeks to break down, and in the meantime they encourage the sour, sulphurous smell of bacterial action.

Spread trimmings on a board or a plaster bat in a warm, airy corner and leave them for a few days. Thin trimmings dry in hours; thick thrown walls may need a week. Break larger pieces into smaller ones to speed things up. A sunny windowsill will do the job nicely, but avoid an oven — clay dried too fast can case-harden on the surface while the interior stays damp.

Slake Slowly and Let It Settle

Fill your bucket roughly two-thirds with dry scraps, then add water until it just covers them. Do not flood it. Too much water means a long wait later while the excess evaporates. Leave it to stand for 24 to 48 hours. The clay will slump into a soft sludge on its own; you are not trying to dissolve it, only to let water work its way between the particles.

After a day, stir with a stout stick or a mixing paddle on a slow drill. Aim for a smooth, lump-free slip the consistency of double cream. If lumps persist, add a little water and leave it another day rather than fighting it. At this stage you have slip and slurry — useful for joining and for casting — but not yet clay you can throw.

Take the Water Back Out

Now the slow part. There are several reliable ways to bring slip back to a plastic state:

• Plaster bats. Pour the slip an inch or two deep onto a clean, dedicated plaster bat. The plaster draws water out from below. Keep that bat for clay only and never use one that has touched casting slip.
• Cotton bags. Ladle the slip into a pillowcase or an old pair of curtains, tie the top and hang it over a bucket. Water drips out; check it every few hours.
• Open buckets. Leave the slip uncovered and stir once a day. Slower, but it needs no extra equipment and is hard to get wrong.

Whichever method you choose, stop when the clay pulls away from the plaster or holds its shape on a spatula. If it is stiff enough to knead without sticking to your fingers, it is ready.

Wedge, Rest and Test

Once the clay is firm enough, wedge it. Wedging removes air pockets and, more importantly, evens out the moisture. A spiral wedge or a ram's head both work; do not rush it. For larger quantities, wedge in batches and stack the pieces together.

Then wrap the wedged clay tightly in plastic and leave it for at least three days, ideally a week. This resting period is what most home potters skip, and it is the difference between clay that throws well and clay that fights back. Moisture migrates through the mass until the body is uniform and plastic again.

Before committing a whole batch, test a small ball: roll it into a coil and bend it around your finger. It should curve without cracking. Press a thumb into it — the dent should hold its shape cleanly. If it feels short or tears at the edges, it needs more rest, or blending with fresh clay.

When Reclaim Misbehaves

Three common problems, three fixes:

• Sticky and clinging. Too wet. Spread it on a plaster bat or leave it unwrapped on a board for an hour, turning it once.
• Crumbly and short. Too dry, or overworked. Mist it lightly with water, wrap it and leave it a few days. Mixing in a third fresh clay usually restores plasticity.
• Foul smell. Bacteria feeding on organic matter in the slip. Unpleasant but harmless. Dry the batch completely and slake it again, or add a splash of household vinegar to the bucket.

Recycled clay behaves best when it is not used alone in huge quantities. Blend a portion into your fresh clay — a third to a half is a comfortable ratio for most stoneware bodies — and it will throw just as sweetly as new clay at a fraction of the cost.