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Pottery and Ceramics Explained: Pt. 2 – Did You Know It’s All About the Clay?

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Experts claim that today there are over 30 different types of pottery styles found in numerous art galleries and museums around the world. Most of these pottery types are distinguished by their various unique firing temperatures, styles of glazing or other finishing techniques.

Yet of these 30 different kinds of pottery – the three most common types of pottery are still Earthware, Stoneware and Porcelain.

But did you know that these types of pottery get both their names and their respective usage based on the type of the clay that they are made from?

As its base, clay is a magnificent “mineral stew” of crushed and eroded feldspar (the main mineral usually found in granite) along with other igneous rocks.

Over many millennium, the feldspar and the rocks break down and is slowly ground into “kaolinite’ the main ingredient found in natural clay. All natural clays contain varying levels of kaolinite.

Think of a clay bank or mine as having layers in a huge birthday cake.

kaolin-pit-prior-to-reclamation1

The layers further down from the surface have high levels of kaolinite in them — with the bottom-most layers being almost pure kaolinite – while each successive layer above have increased mixtures of igneous rock along with other minerals, until you reach the top layer of dirt.   It’s these variations or layers that create the different types of pottery clay and that give each type their name.

 Earthware

As you might have guessed “Earthware” is pottery that comes from clay that is usually found fairly close to the surface.

It is what many mothers of active kids refer to as ‘red clay dirt’ – and not in a good way. But in actuality earthware clays can range in color from very light creams, tans and browns to terra cotta or brick red.

While Earthware pottery can have a texture that can be almost silky smooth, often grog (sand or ground up fired clay particles) is added to the raw clay to prevent excessive shrinking and cracking.

It’s the grog that can give earthware pottery a rougher or more textured feel and appearance.

And since earthware clays are very common and are inexpensive, they are still used to create the bulk of today’s handcrafted pottery — earthware being somewhat more fragile than either stoneware or porcelain.

Due to its make-up, earthware pottery is very porous and must be glazed at a high firing temperature in order to hold water or liquids.  And all pottery must be fired with a food-grade glaze (one without any lead in it) before it can safely store food.

 Stoneware

The greater the kaolinite levels that are in the clay, the less porous and the stronger its structure will be when the resulting piece is fired.

Stoneware can withstand higher kiln temperatures, so little if any water absorption is found, even with an unglazed piece. Stoneware clays create a dense, more durable and very scratch resistant pottery piece.

And because of these factors, stoneware is considered to be for better pottery that is going to be used every day or in heavy-duty environments.

Stoneware was used extensively, here in North America for common houseware items like jugs, bowls, mugs and crocks from the 19th century until the early part of the 20th century.

“American Stoneware refers to the predominant houseware of 19th century North America—stoneware pottery usually covered in a salt glaze and often decorated using cobalt oxide to produce bright blue decorations.”

At the extremely high temperatures that Stoneware and Porcelain are fired, little, if any porosity is noticed, even if the pot is unglazed.

Just as higher temperatures yield greater water retention, pots fired at stoneware/porcelain temperatures are much stronger and durable for everyday usage.

Porcelain

Porcelain pottery is made from Kaolin (or “China” clay) that is made from pure kaolinite along with other materials such as ground glass, alabaster or bone ash.  And each kind of porcelain is called “soft paste”, “hard-paste”, or “bone china” accordingly.

Porcelain originated in China sometime during the Shang Dynasty (1600–1046 BC), but become highly prized by Western traders during the Tang Dynasty (618–907 BC).

From there it the technique or creating porcelain paste spread throughout the world from the Middle East to Europe, to North and South America.   Porcelain is one of the most durable types of pottery – which is why many ancient porcelain artifacts are still being uncovered, more or less intact.

Porcelain is hard, usually white, vitreous (has a translucent glassy-like appearance) and is scratch resistant.  Oddly enough one of the most famous American porcelain dishware makers in the US was once active just over the mountain in Erwin, Tenn.

The now defunct Southern Potteries created the durable Blue Ridge dishware brand.  Blue Ridge porcelain was well known in the day for their unique underglaze decorations and colorful hand-painted patterns.

Even though each set of dishware used the same patterns – the hand-painting means that no two pieces (even in the same set) are ever exactly alike.

The Blue Ridge porcelain plant started production in the early 1930’s due to the quality of nearby kaolinite and feldspar deposits and continued until its closing in 1957.  Currently Blue Ridge dishware is highly sought after by collectors and antique lovers.

 

As you can see we have a very wide selection of the 3 basic pottery styles.

While Mountain Made doesn’t specialize in vintage pieces like the Blue Ridge dishware, we invite you to come by our gallery and browse the works by our studio potters and ceramic artists – we think you just might find some pottery that will be highly collectable in the future!

 

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