Pottery clay: stoneware, earthenware, air-dry and polymer

Kiln clay for the wheel and hand-building, plus air-dry, paper and polymer clay for working without a kiln, sorted by what the maker lists.

Coned-up mound of grey clay on a wheel head
Photo: Martin Cathrae, CC BY-SA 2.0, via Flickr
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What kinds of pottery clay are here?

Pottery clay in this category splits into two worlds. Kiln clay (AMACO, Rocky Mountain Clay, Old Potters, TORISING, ReArt) must be fired to a stated cone. No-kiln clay hardens on its own or in a home oven: air-dry clay from Crayola, DAS, Activa, FIMOair and Sculpey; paper clay; polymer clay from Sculpey and FIMO; and non-drying oil-based clay for sculpting.

Mixing them up is the most common first-purchase mistake, so check the clay type on every listing.

How do you choose clay for pottery?

  • Firing range (cone). Match the clay to the kiln you can use. Low-fire clay is listed at cone 06–04 (TORISING, Old Potters) or 06–5 (AMACO Terra Cotta 77). Mid-fire stoneware is cone 6 (Rocky Mountain B-Mix) or 6–10 (Old Potters white stoneware).
  • Clay body. Stoneware is dense and durable once fired; earthenware stays more porous and fires at lower temperatures; porcelain is the smoothest and least forgiving. Our three-way comparison covers the trade-offs.
  • Bag size. 5–10 lb bags suit a first try. Wheel throwers go through 25–50 lb boxes quickly.
  • No-kiln clay. Air-dry clay cures in roughly a day per listed thickness (Activa lists ¼ in in 24 hours). Polymer clay bakes in a home oven, for example FIMO Soft at 230 °F for 30 minutes as listed.

Which clay for which setup

Needs a kilnWheel throwingFood or water use
Stoneware (cone 5–6)✓ Yes✓ Yes~ Only with a suitable, correctly fired glaze
Low-fire earthenware (cone 06–04)✓ Yes✓ Yes~ Only with a suitable, correctly fired glaze
Air-dry clay✗ No~ Kids' kit wheels only✗ No
Polymer clay✗ Home oven✗ No✗ No
Oil-based clay✗ Never hardens✗ No✗ No

Which clay fits your situation?

Clay mistakes to avoid

  • Firing clay beyond its listed cone; it can slump, bloat or stick to the shelf.
  • Sizing a piece without allowing for shrinkage. Use the shrinkage calculator before you cut a slab.
  • Sealing air-dry clay and treating it as waterproof for food or drink.
  • Letting clay dry unevenly, which causes cracks. See why pottery cracks and how to reclaim clay.
  • Sweeping dry clay. Dried clay dust contains silica; wet-wipe instead.

Clay: questions

What is the best clay for beginners?
If you have kiln access, a smooth cone 5–6 stoneware is forgiving. Without a kiln, start with air-dry clay for hand-building or polymer clay for small detailed pieces.
Can you use air-dry clay on a pottery wheel?
Kids' kit wheels ship with air-dry clay, so it works for small pieces. Air-dry clay is not fired, so the results are decorative only.
Is air-dry clay waterproof?
No. Sealers help against moisture, but air-dry pieces should not hold water or food. See how to seal air-dry clay.
What does cone 06 or cone 6 mean on clay?
It is the firing range the clay is made for. On the Orton chart, cone 06 is 1,828 °F and cone 6 is 2,232 °F at a medium rate; see the cone chart.
How much does clay shrink?
It varies by clay body and cone; check the maker's data sheet and test with a marked tile. Our shrinkage calculator does the math.
What is the difference between stoneware and earthenware?
Stoneware fires hotter (often cone 5–10) and ends up denser; earthenware fires around cone 06–04 and stays more porous. See stoneware vs earthenware vs porcelain.