Some of the best places to look for clay include:
river banksstream bedsroad cutsnaturally exposed earth such as in canyons or gulliesconstruction sites
Always make certain to get written permission from the land’s owner before digging any clay. It is especially important to get permission when the clay is in a construction area. Follow safe practices, such as staying clear of dangerous terrain or machinery. Never dig clay from National or State Parks or Monuments; disturbing the natural habitat is often illegal and can carry some serious consequences. The finer the mesh used, the fewer inclusions your working clay will have. I suggest using a 50-mesh screen, although a 30- or 80-mesh will do. Don’t go any finer than an 80-mesh screen, as that can negatively affect the clay’s usability. Once the clay has been cleaned and slaked down, you will want to bring it back to a working consistency. If you want to test your clay for its use as a slip, create test pieces either using the clay body you will be working with, or a white clay body. Either of these should have a higher maturation temperature than you believe your local clay has. Decorate the test pieces with the slip, using various techniques. When testing for the clay’s maturation temperature, make sure you always fire your test pieces on bisqued plates which are larger in circumference than the test pieces and are made of a higher firing clay. Other attributes you may want to test for include shrinkage and absorption rate. Record all results for your trials and determine if you have discovered the maturation temperature. If not, run further tests. For example, the clay may seem to be fairly mature at cone 02, but you would like to check to see. In that case, run a second series of test pieces, firing them at cone 01, 1, and 2.
