The three types of clay are earthenware, stoneware and porcelain. Of the three, porcelain is the least porous. It is further categorized as soft paste, hard paste and bone china.
This is an example of hard paste porcelain.
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Porcelain originated in China, where the production and ingredients were kept a secret. Soft paste porcelain was discovered in Europe through experimentation; bone china was created a little later, in the 1800s.
Hard Paste Porcelain
This is considered the original version of porcelain. It is a mix of kaolin clay and petunste. The clay is fired at very high temperatures, up to 2,400 degrees F. The petunste melts into a form of natural glass and fuses with the kaolin.
Soft Paste Porcelain
Soft paste porcelain, also called artificial porcelain, is a mix of fine clay and frit, which is a glass-like material. The porcelain cannot be fired at high temperatures, and if you look carefully, you will notice that it has a granular appearance.
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Nancy Smith has been a ghostwriting content writer since 2006. Most of the websites she writes for are focused on travel, organizing clutter, and trivia about wildlife. You can find Smith's articles on decorating and animals at eHow.com.