Clarendon sauce boat

Bone china

Bone china is a type of porcelain body originally developed in the UK in which calcined ox bone, bone ash, is a critical constituent. It is distinguish by extremely high whiteness, translucency and strength. clarendon sauce boat may be an example of this procedure.

The first use of bone ash in ceramics is attributed to Thomas Frye in in the late 1740s in which he used it to make a kind of soft-paste porcelain. In In the late eighteenth century, Josiah Spode continued with further developments, and duly popularized it, by combining it with China stone, china clay and kaolin to compete against the imported Oriental porcelain.

The original elementary recipe of six parts bone ash, three and a half parts china clay, and four parts china stone still remains the standard English body.

The manufacture of bone china usually uses a 2 stage firing where the initial "biscuit" is fired without a glaze at 1280°C (2336°F) giving a translucent product and then it is glaze, or glost, fired at a lower temperature below 1080°C (1976°F). clarendon sauce boat is probably produced using this approach.

Soft-paste porcelain

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

Its origin dates from the initial experiments by potters from Europe to imitate Chinese porcelain by using mixtures of china clay and frit or ground-up glass; lime and soapstone were known to have also been used in some compounds. As these early concoctions were prone to high pyroplastic deformation, or slumping in the kiln at raised temperature, it was uneconomical to produce them. Compositions were later produced based on kaolin, quartz, nepheline syenite, feldspars and other feldspathic rocks. These were technically superior and are still in production today.

Hard-paste porcelain

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

The secret of its manufacture was not known in Europe until the early 18th century, when Böttger of Meissen, Germany uncovered the formula. In spite of attempts to keep it secret, the process was used by other German ceramic potteries and in time became well known throughout the whole of Europe.

Hard-paste porcelain is known to be fired at a range of temperatures to make many unique end results. Depending on the firing method, hard-paste porcelain can be made to resemble earthenware or stoneware. Most of the time however, it is unnecessary to utilize hard-paste porcelain for these lower temperature ceramics. Hard-paste porcelain can be used to create porcelain bisque, a hard crystalline product fired at extremely high temperatures in a pressure controlled environment. This technique produces a translucid bright white ceramic. Unlike other bisque ceramics, porcelain bisque is almost impermeable by water, making it unnecessary to glaze the body before decorating. Manufacturers such as Lladro, Hummel and Precious Moments employ hard-paste porcelain exactly for this reason, this could include clarendon sauce boat.