Porcelain & China
Glazed earthenware made of porous clay and fired at a low temperature has been used for thousands of years for cooking pots. An earthenware pot absorbs heat slowly, but retains it well making it suitable for long slow cooking in the oven.
The glaze on earthenware pots is intended to make them less absorbent to liquids, however it is quite normal for this to become 'crazed' due to expansion caused by cooking heat. This has to be expected and is most noticeable on the tradionally-made brown and red clay types of earthenware made in France and other Mediterranean countries. With repeated use the pot or dish will become 'seasoned' and less porous as it becomes sealed by oil absorbed from cooking.
Before use a new pot should be 'cured' and this is done by filling it with potato peelings and salted water. Put it in the oven and bring to a simmering heat before leaving it to cool.
Earthenware was originally intended for use on wood fires and will not stand up to the direct heat on modern hobs.
Round vessels can be used on low temperatures with a heat diffuser and all earthenware will withstand normal oven temperatures.
Never subject earthenware to sudden changes in temperature.
After use leave the pot to cool before washing. Dry the pot thoroughly preferably in a warm oven and store on an oven shelf with the lid off.
Earthenware is usually microwave proof but check it carefully to make sure that there is no metal in the glaze. As it absorbs moisture easily and can overheat, make sure that it is thoroughly dry before adding the food and putting in the microwave.
Stoneware differs from earthenware by being fired at a much higher temperature resulting in a very strong non-porous product. It is used for jugs, storage vessels and hard wearing, heat resistant bowls and dishes.
The care and treatment is the same as for earthenware.
Terracotta & Unglazed Earthenware:
Potato bakers, chicken bricks and bread crocks.
Do not use detergents with terracotta or unglazed earthenware: wash in warm water with salt or vinegar and, if necessary a little soap.