In my shop, The Northern Home Shop , I sell china that is made of different types of pottery. I sell some so called earthenware pottery, or more correctly faience and feldspar pottery, and I sell stoneware. But it could be practical for the uncertain buyer to have a guide to pottery, a sort of short definite guide, and that is what this is.

One of the most important aspects of pottery is glazing, so before we go into the different types of pottery, let’s get the glazing out of the way first.

Glazing is important because it determines the appearance of a piece of pottery, and it is also an integral part of the piece itself as it can give an otherwise brittle piece the strength and stamina to weather decades of use.

Glazing
In pottery when you speak about glazing you speak about a process of coating the pottery piece with a thin layer of glassy material. After applying this covering, the glaze, the pottery is fired and the powdery coating melts into a glass-like coating.

For some pottery glazing is critical, such as with earthenware pottery. That type of pottery doesn’t have the structural integrity to resist liquids because it is so porous. Without a glaze the pottery would be soaked eventually, and thus destroyed.

Glaze is also the means of decoration in pottery. Both earthenware and stoneware are limited in their natural color range, although earthenware has a broader colour band than stoneware. Aesthetic concerns often require a smooth and pleasing surface, a degree of gloss, and colours. Glazes can also enhance any underlying inscribed, painted or carved pattern on the pottery – as well as protect the same.

Glaze recipes are carefully formulated to melt at appropriate temperatures and produced a surface with desired characteristics. Glaze may be applied by dusting a dry mixture over the clay, or by dipping the piece in the slurry of glaze and water. Liquid glaze can also be applied by splashing or with a brush. Brushing tends not to give an even covering, but can be effective with a second coating of a coloured glaze as a decorative technique.

Decoration that is applied directly onto the pottery is often called underglaze. An example of underglaze decoration is the well known blue and white porcelain produced in China and Japan.

Decoration applied on top of a layer of glaze is called overglaze. Overglaze methods include putting more layers of glaze on a piece, or by applying non-glaze substances like enamel or metals over a glaze. Inglazed is simply a staining of the underglaze to produce patterns and colour shifts.

Genuine Porcelain
It wasn’t until in the first quarter of the eighteenth century that Europeans managed to duplicate the process of making porcelain. Porcelain is created by high heat in a reduced oxygen atmosphere that crystallizes the silica in the clay, in effect turning the silica into glass.

Until the production technique was duplicated in Meissen, Europe could not make porcelain – but they did have access to pottery that required less heat and less industrious techniques, so called earthenware.

Vitreous Porcelain
Vitreous means glass-like, and this porcelain was created in the US. Like genuine porcelain it has a certain translucency, yet at the same time it has a more practical production process.

It is almost as easy to make vitreous porcelain as it is to make earthenware pottery. The same wide range of colors as earthenware available on this product when underglazed.

Stoneware
Stoneware is a semi-vitrified products with glasslike properties. It is usually decorated, underglazed, and fired once using a narrower spectrum of colors because of the high firing temperature. Inglaze can also be used for a better colour range. Genuine porcelain is an excellent example of stoneware, but usually we think of more mundande pottery when the term is used.

Originally stoneware was vitreous, more or less based on clay with low iron levels and a high sintering temperature. Sintering is a method for making objects from powder, increasing the adhesion between particles as they are heated. Sintering traditionally serves for manufacturing ceramic objects, and has also found use in such fields as powder metallurgy. Sintering relates to diffusion.

Stoneware turns grey in reduction firing and yellow in oxidation firing. Stoneware is sometimes salt-glazed. Some versions of stoneware are currently made using methods reminiscent of vitro porcelain using a stoneware firing method. Some stoneware is also made with silica instead of aluminium oxide to make it even stronger and whiter.

Bone china
Bone china is England’s answer to the translucent genuine porcelain from the rest of Europe. It is even more translucent than genuine porcelain from certain bone china manufacturers despite the fact that it is has a lower glass content than genuine porcelain.

The higher levels of crystalline material mean that rims are stronger, in the same range as types of porcelain containing high levels of aluminium oxides.

Earthenware
Porous items with completely glazed surfaces, that are fired on stilts. Many of the factories, which make earthenware, use unglazed bases (dry footing) for cups and mugs, which risks discoloration of the unglazed area.