# How to Make Clay From Soil in Your Own Garden URL: https://myclay.online/blog/how-to-make-clay-from-soil Published: 2026-08-06 Category: Wild clay Tags: Wild clay, Materials, Beginners Reading time: 5 min > Clay is already in the soil — extraction, not creation. Slake the dirt in water, stir hard, pour off the cloudy water before the sand settles, let the clay settle out of it, then dry the sludge on plaster. The phrase is a little misleading. You cannot manufacture clay from soil — clay is a specific mineral produced by rock weathering over geological time. What you can do, and what everyone actually means, is **separate the clay that is already in your soil from the sand, silt and organic matter mixed in with it**. > **From the studio:** I ran the jar test on three spots in one garden and got wildly different answers — a sandy loam by the path, and a band under the vegetable bed that gave nearly half its volume back as clay. Ten minutes of testing saved me from digging in the wrong place for an afternoon. That works because of settling speed. Drop a handful of soil into water, stir it, and gravel sinks in a second, sand in twenty, silt in a few minutes, and clay stays suspended for hours. Time the pour and you separate them. ## Dig in the right place **Go below the topsoil.** The dark, crumbly upper layer is mostly organic matter and is the worst source. Clay content generally increases with depth. Anywhere from 30 cm down is worth trying, and a vertical face — a ditch, a bank, the side of a trench — lets you see the layers directly. **Signs your soil holds clay**: puddles that sit for days after rain, ground that becomes sticky and slippery when wet, deep straight-sided cracks in dry weather, and soil that clumps solidly around a spade. **A first check**: wet a pinch, rub it between your fingers, and roll it into a thin coil. If it wraps around your finger without cracking, there is plenty of clay in there. If it crumbles instantly, this spot will not repay the effort. ## The extraction, step by step **1. Dry and break up.** Spread the soil out to dry completely, then crush the lumps. Dry material disperses in water in hours; wet clods take days. **2. Slake.** Put the crushed soil in a bucket and cover with about twice its volume of water. Leave overnight. **3. Stir hard.** Break everything up into a thin, muddy soup. Pick out roots and stones as you go. Thin is better than thick — this is not the stage to conserve water. **4. Decant on a timer.** This is the actual separation. Stir vigorously, then count 20 to 30 seconds. Sand and grit reach the bottom in that time; clay does not. Pour the cloudy water off into a second bucket, stopping as soon as you see grit moving. Add fresh water to the first bucket, stir, wait, pour again. Two or three rounds recovers most of the clay. What is left in the first bucket is clean sand — keep it, since you may want to add some back later. **5. Sieve.** Pour the cloudy water through a kitchen sieve or a piece of window screen to catch floating organic matter. An 80-mesh screen gives a fine, smooth body. **6. Settle.** Leave the second bucket undisturbed for one to three days. The clay forms a dense layer at the bottom under clear water. **7. Pour off the clear water.** Carefully, or siphon it with a length of tube. What remains is clean clay slurry. **8. Dry to working consistency.** Spread the slurry roughly 3 cm thick on a plaster bat, an old cotton sheet in a colander, or a bed of newspaper on a board. Turn it when the top stiffens. It is ready when it holds its shape without sticking to your hands. **9. Wedge.** Thoroughly, to even out the moisture and remove air. Cut it with a wire and check that the face is uniform. ## Test it, and test it low Garden clay is almost always low-firing, and often contains fluxes that make it melt far below stoneware temperature. - Make a **[shrinkage bar](/blog/how-to-process-wild-clay)**: scribe exactly 10 cm on a strip and measure it dry and fired. Over roughly 14 percent total shrinkage means it will crack, and wedging in 10 to 25 percent fine sand or grog will fix it. - **Fire test tiles at cone 06 first**, standing them on scrap shelf or a bed of sand. Only go higher if they survive intact. - Watch for **bloating** — swollen bubbles in the fired tile, caused by organic matter or high iron. Slower firing helps; so does more thorough sieving. ## If it does not make a good pot Not every garden yields a throwing body, and the effort is not wasted either way. Fine-sieved garden clay thinned with water makes an excellent [decorating slip](/blog/how-to-make-colored-slip), in a colour you cannot buy, on a commercial body that you know is reliable. Some of the most interesting surfaces in studio pottery come from exactly that combination. ## Judging what you got When the sludge finally reaches working stiffness, four quick checks tell you what you are holding. **Roll a coil and bend it.** A full wrap round your finger with no cracking means genuinely plastic clay. Cracks at the outside of the curve mean it is short, and 10 to 20 percent of a plastic commercial ball clay wedged in will fix it. **Feel for grit.** Any grittiness means the sieve was too coarse. Fine for sculpture, unpleasant to throw. **Watch the shrinkage bar.** Over about 14 percent total shrinkage and it will crack; add fine sand or grog. **Smell it.** A strong sulphurous or organic smell is normal in clay from waterlogged ground and tends to fade. It also predicts a body that benefits from a slow bisque, since organic matter needs time and oxygen to burn out cleanly. None of these is a pass or fail. Garden clay that fails as a throwing body still makes an excellent slip, a good sculpture body when grogged, or a colour you could never buy — and you now know exactly which of those you have. ## Where to go next The fuller version of this method, including the test firing sequence, is in [how to process wild clay](/blog/how-to-process-wild-clay). To find better material than your own garden, see [where to find natural clay](/blog/where-to-find-natural-clay). And if your clay turns out to be unfireable, [how to make coloured slip](/blog/how-to-make-colored-slip) is a good use for it. ## Frequently asked questions **Can you make clay from any soil?** Only from soil that already contains clay. Pure sand or heavily organic topsoil yields nothing. Dig below the topsoil — clay content usually rises with depth. **How much clay do you get from a bucket of soil?** Anywhere from nothing to about half the volume. A heavy clay subsoil can yield 40 to 50 percent; a sandy loam might give 10 percent or less. **Is garden clay good enough for pottery?** Sometimes. It is usually low-firing and often needs sand or grog added to stop it cracking. Test fire it before making anything you care about, and start at a low temperature. --- Source: https://myclay.online/blog/how-to-make-clay-from-soil — https://myclay.online/