What is the easiest way to dig a hole in clay soil?

Answer 1

Rework Dry Clay

and Process Self-dug Clay # Clay must be totally dry. There is no need to break up dry clay.

PRECAUTIONS:

Be sure it has no plaster chips in it - plaster causes pop-outs when bisque fired. Leather hard clay or moist clay does not slake well because it is not porous like dry clay is. Instruct students to handle the dry clay without making dust. A lot of airborne dust is not healthy to breath.

see health hazards page # Flood clay with clear water (or drop it into water) in something like garbage cans. Use enough water so clay is totally under water. # Never stir it. Stirring stops up the porosity and prevents good slaking (soaking to mush). # In a few days, even huge chunks of dry clay will slake to mush. Go to step 6 below. SELF-DUG CLAY VARIATION

If you dig clay yourself, it often has impurities that need to be removed. # Get it totally dry. # Slake it as described in 3 above. # When it is all soft and mushy, stir it until it is a slip. I use a mixer on an electric drill or a blunger. Add water if needed to liquify it. # Pour the slip through a screen similar to window screen. I use the mesh at prevents flys and mosiqitoes from entering the windows. # The screening removes stones, roots, and other trash that causes trouble. The chief culprit is limestone. Limestone, like plaster, pieces cause pots to break after bisue firing. # When the clay has settled and turned to mush, remove extra water from top. Dip water off or siphon it off. # You can stiffen the mush by allowing it to set for many months with the lid off. To dry it faster, spread the mush a few inches thick on clean dry porous surfaces. I use, dry plaster, clean concrete, canvas, denim, etc. Smooth the top to avoid getting small dry pieces on the surface. The breeze from a fan at night helps and/or place it where air from a heat register hits it (do not block the air flow). # When it is nearly dry enough, I make coils as thick as my arm and set them around like big arches (a foot tall) and they are ready to wedge and use in 24 hours or less. This clay can be stored forever in an airtight plastic.

In ancient China, potters stored moist clay in caves for the next generation to improve the plasticity of the clay. If it is to be stored long-term, double wrap it. Double wrapping in plastic bags from the supermarket works. Students can bring in hundreds of these. top of page

notes on digging clay PLASTICITY - Some clay is too sandy and some is to sticky. When I prospect I look for a clay that can be rolled between my hands into a pencil thick coil of soft clay and wrapped around my finger without cracking. If the coil cracks, it may be too sandy or its clay particles my be too large. Sticky clay tends to be cling to my hands too much. It will often have severe drying shrinkage and tend to crack during drying. Clays are often blended to get the right properties. Commercial clays can be added to balance the mix. Ball clay adds plasticity. Crude ground fireclay, china clay (kaolin) fine sand, and/or grog reduce plasticity. IMPURITIES - Most common clay contains impurities, often in the form of iron oxide and sand. Some sand can be removed by making a thin slip. The sand settles to the bottom first. Allow the sand to settle a short time. Then decantor the clay water and discard the sand in the bottom. Allow the clay to settle and process it as described in #6 above. Iron impurites are not easily removed. Iron causes the clay to melt more easily, so it may not work for stoneware, but all common clays are fine for earthenware. It generally fires to look like the common clay flower pots. GOOD USES OF IMPURE CLAY - Potters who make high fire stoneware sometimes add small amounts of impure local clay to their clay body to add character and blemishes. I use a brick clay to add color and iron spots. Stoneware potters also use local clay as a source of glaze material. These "slip glazes" have been used for thousands of years for lining jugs and traditional crockery. WHERE TO LOOK FOR IT - Check in stream banks, contruction sites, roadway cuts, any place that gets slippery after a rain and sticky as it starts to dry. For me, teaching ceramics includes having students prepare and rework clay, fire kilns, and keep the place clean. This is a web page about safely working with clay.

http://www.goshen.edu/art/DeptPgs/Hazards.html This is a web page about safely cleaning up in a clay studio or classroom.

http://www.goshen.edu/art/DeptPgs/clean.html Back to Goshen Art Department Safety Page and Links ---- © Marvin Bartel, 2001. Goshen College ceramics students may print out a copy for their own use. Any other copy or publishing is prohibited without permission. CONTACT

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Updated 10-17-2001, Marvin Bartel

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