What is the difference between stoneware and earthenware?
The most obvious difference between stoneware and earthenware is temperature, stoneware pots are fired above 1200°C and earthenware is fired below this temperature. This is however a simplistic definition.
There are other differences particularly in the way the glaze works with the clay body, in earthenware the glaze lays on top of the body and is adhered to it in the firing as a glassy layer but remains separate from the clay. With stoneware, the glaze melts into the body creating an integrated layer in which substances within the clay, principally metal oxides, are combined with the glaze giving the characteristic subtle effects. Stoneware glazes are usually more subdued with more naturalistic appearance whereas with earthenware, brightly coloured glazes that might be lost in higher firing can be used. In firing stoneware, it is generally biscuit fired to around 1000°C then glaze fired at a temperature suitable for maturing both clay and glaze together. Earthenware can be fired in the same way, that is with a low biscuit and higher glaze however it may also be fired to mature the clay in the biscuit (bisque) firing, “high bisque” while the glaze is fired at a lower temperature.
Stoneware is hard and more durable than earthenware and is more resistant to scratching and breakage, it is generally vitreous so does not readily absorb moisture. Stoneware clays are required for reduction firing, salt glazing and wood-fired ware. Porcelain is a more purified type of stoneware; it is very white and free from any oxide inclusions. Bone china is an exception as it is fired high in bisque firing followed by a low earthenware glazing.
Earthenware is usually lighter weight with a softer glaze that is more susceptible to scratching and chipping. The colourful wares from Mediterranean and north African areas are examples of earthenware pottery. Earthenware was widely used in the British tableware industry but it has now been replaced by hotelware bodies which although frequently fired below 1200°C could be regarded as stoneware because they have complex clay formulations including fluxes that enable extremely strong, vitrified wares to be produced.
