Ashworth small bread and butter plate

Bone china

Bone china is a type of porcelain body initially used in the UK in which calcined ox bone, bone ash, is an important constituent. It is distinguish by extremely high whiteness, strength and translucency. ashworth small bread and butter plate may be an example of this procedure.

The first use of bone ash in ceramics is attributed to Thomas Frye in the mid eighteenth century in which he used it to introduce a kind of soft-paste porcelain. In At the close of the 18th century, Josiah Spode continued with further developments, and subsequently popularized it, by mixing it with China stone, kaolin and china clay to compete with the imported Oriental porcelain.

The initial elemental formula of six parts bone ash, four parts china stone, and three and a half parts china clay still remains the standard English body.

The production of bone china routinely involves a 2 stage firing where the initial "biscuit" is fired without a glaze at 1280°C (2336°F) giving a semiopaque product and then it is glost, or glaze, fired at a lower temperature below 1080°C (1976°F). ashworth small bread and butter plate is probably manufactured using this approach.

Soft-paste porcelain

Soft-paste porcelain is a type of porcelain and consequently a ceramic material.

Its origin dates from the initial ventures by European potters to clone Chinese porcelain by using compositions of china clay and frit or ground-up glass; lime and soapstone were also known to have been included in some formulations. As these first compounds were prone to high pyroplastic deformation, or slumping in the kiln at high temperature, they were not economical to manufacture. Combinations were later developed based on kaolin, nepheline syenite, quartz, feldspars and other feldspathic rocks. These were technically superior and continue in production today.

Hard-paste porcelain

Hard-paste porcelain is a hard, dense ceramic that was first produced from a combination of the feldspathic rock petuntse and kaolin fired at extremely high temperature. It was first made in China around the ninth century.

The secret of its manufacture was unknown in Europe until the early 18th century, when Böttger of Meissen, Germany found the formula. Despite attempts to keep it secret, the process was taken up by other German ceramic potteries and in time became widely known throughout Europe.

Hard-paste porcelain can be fired at a range of temperatures to manufacture a multitude of unique end results. Depending on the firing process, hard-paste porcelain can be manufactured to resemble stoneware or earthenware. Generally however, it is unnecessary to use hard-paste porcelain for these lower temperature ceramics. Hard-paste porcelain can be utilized to make porcelain bisque, a hard crystalline product fired at very high temperatures in a pressure controlled environment. This method generates a semitransparent bright white ceramic. Unlike other bisque ceramics, porcelain bisque is almost impermeable by water, therefore it becomes unnecessary to glaze the body before decorating. Manufacturers such as Hummel, Precious Moments and Lladro employ hard-paste porcelain simply for this reason, this could include ashworth small bread and butter plate.