Pottery, earthenware, stoneware,
china, porcelain or bone china?
Pottery : Clay that has been shaped and fired in a kiln
The difference between earthenware, stoneware, china, porcelain and bone china is strictly which clay and what temperature.
Earthenware is the basic pottery we are all familiar with. One of the oldest crafts, potters can be found wherever there is a good deposit of Clay ( such as The Blue Mountain Pottery in Collingwood using the red clay in the area)
Earthenware is fired at under 1000C and the resultant product is a porous, somewhat fragile product. The fact that it is porous has been used for centuries as a means to cool liquids in hot climates. In order to have the vessel hold water the inside or outside must be glazed. Glaze is a mixture of ground glass and colouring that is applied to the vessel and then fired so that the glass melts and forms a watertight covering. In interesting and fairly inexpensive method of glazing crocks and jugs was used in the early 19th Century by simply throwing a shovel full of salt into the kiln at the right time. The salt vaporized and then settled on the crocks as a shiny clear glaze, usually with the characteristic orange peel texture. Medicine Hat Alberta had the right combination of clay, water and gas to produce a great Pottery Industry. Starting in 1907, the Medalta family of firms produced much of Canada’s crockery through the early part of the Century. This product is a great collectible but the collector should be well aware of the different Factories and marks. Visit http://www.medalta.org/ for a fascinating look at the history of these companies.
At the other end of the spectrum is Porcelain. Discovered in China about 2200 years ago, it is a white clay (kaolin) mixed with a ground rock (pentuse). The difference comes in the firing. Whilst earthenware clay will sag and slump into a mess at too high a temperature, Kaolin wont. However at around 1400C the rock melts, fuses with the clay and forms a hard, resonant product. So hard that you cannot scratch it with a file and when you strike it, it rings. There is a story that a major Canadian Dept Store (probably Eatons) wanted to demonstrate the strength of porcelain and it had a sports car supported by four inverted teacups, one under each tire.
Porcelain was first brought to Europe by Marco Polo and every body from Potter to Prince tried to jump on the bandwagon and produce a fine white-bodied product. The problem was the clay. Until kaolin was found in Europe, all the alchemists could do was experiment with clays and glass and ground rock and finally they managed to produce what was called soft porcelain. This product melts at the high Porcelain temperatures and is therefore fired at a lower temperature. This results in a grainy body that is creamier in colour than Hard Porcelain and is slightly porous causing the glazes and the colours to be softer. When kaolin was discovered in Saxony in 1707 the great era of European Porcelain began. The factory at Meissen, under the protection of the Prince of Saxony, managed to keep the secret formula for 60 years until another accidental discovery of Kaolin near Sevres, France allowed the information to spread.
England soon had its own factories and with the decline in the trade from China both for political and fashion reasons, the demand for porcelain, or China as it was often called, skyrocketed.
In 1796 Josiah Spode perfected his formula for English China which was made up of the Kaolin and Pentuse (from Cornwall) and almost 50% calcined bone. The resultant product was harder, whiter, more translucent and cheaper to produce than Hard Porcelain.
English Bone China became the world standard for dinnerware.
Meanwhile, with the growth of the middle classes there was a great demand for serviceable tableware that resembled the upper class services but at a middleclass price.
Earthenware was too heavy, too fragile and did not compare.
Potters taking advantage of the of the higher temperatures of the Porcelain Kilns experimented with a variety of clays until they could produce a clay that would become vitreous (glassy) and retain its shape. Since the resultant product resembled stone in its hardness it was called Stoneware. Invented in China at the same time as Porcelain, it was not realizable in Europe until the invention of the higher temperature kilns.
Stoneware was inexpensive, used all the existing earthenware skills and techniques, easier to decorate since the fired surface is not porous. And was much harder to chip.
Although the fineness of porcelain dinner ware could not be obtained, practical, colourful, and inexpensive china could grace any housewife’s table.
If you go into a store (or your China Cabinet) and pick up a cup and it has no marking on the bottom, what is it?
If it is too light for earthenware, and too heavy (thick) for porcelain and not marked bone china then it is either a very good stoneware or what is called Fine China
Fine China is very similar to bone china but less expensive aluminum silicates (sands) are used instead of the bone ash. It does not have as white a body, tends to be grey and therefore does not have quite the beauty (or cost) of bone china
The joy of collecting things made of clay is that the collection can fit any pocketbook. From Wade miniatures found in Tea, to Medalta Crocks to Distinctive teacups From Royal Doulton to Limoges to Meissen the choices are unlimited, every piece has its story and its charm.