People may enjoy sculpting with clay, but not many have access to a kiln for firing pieces of pottery. While it may be tempting to think that clay can be fired in a regular oven, oven-dried clay will not perform like kiln-fired clay. There are clays made for oven drying, but they cannot be used as dishes or near water.
Pug Clay - Kiln Clay
Pug clay comes in a variety of firing grades, measured in cones, but all must be kiln fired. Pug clay cannot be fired in a regular oven. Temperatures in a kiln reach up to 2,000 degrees Fahrenheit and cause the clay to harden. Once pug clay is glazed and fired again, it can be used as dinnerware, sculptures, vases or for any other use.
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There are clays that harden in a standard oven when baked for an hour at 350 degrees. These are specialty clays that must be purchased for this specific purpose. Look for the "oven craft" or "conventional oven" designations. Follow directions carefully.
Polymer clays are made of waxes, oils and minerals. They are versatile and colorful, but they are not standard clay. They do not create stoneware or ceramics. They do harden when baked in a conventional oven.
Specialty clays also include self-hardening clays. Look for a variety of colors such as marble or Mexican pottery. These clays air dry to a rock-hard finish, and can be sealed to make the finished products waterproof. Decorating is done with acrylic paint rather than glaze.