Holyrood tea saucer

Bone china

Bone china is a type of porcelain body originally used in the United Kingdom in which calcined ox bone, bone ash, is a major ingredient. It is characterised by extremely high whiteness, strength and translucency. holyrood tea saucer may be an example of this procedure.

The initial use of bone ash in ceramics is assigned to Thomas Frye in seventeen-forty-eight in which he used it to introduce a kind of soft-paste porcelain. In In the late eighteenth century, Josiah Spode continued with further developments, and subsequently popularized it, by mixing it with china clay, China stone and kaolin to compete against the imported Oriental porcelain.

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

The manufacture of bone china commonly involves a 2 stage firing process where the first "biscuit" is fired without a glaze at 1280°C (2336°F) giving a translucid product and then it is glost, or glaze, fired at a lower setting less than 1080°C (1976°F). holyrood tea saucer is probably manufactured using this process.

Soft-paste porcelain

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

Its origin dates from the early attempts by European potters to replicate Chinese porcelain by using compositions of china clay and ground-up glass (otherwise known as frit); soapstone and lime were known to have also been used in some mixtures. As these initial formulations were prone to high pyroplastic collapse, or slumping in the oven at raised temperature, they were uneconomic to manufacture. Compounds were later produced based on nepheline syenite, feldspars, kaolin, quartz 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 initially made from a mixture of the feldspathic rock petuntse and kaolin fired at extremely high temperature. It was first produced in China in about the 9th century.

The secret of its manufacture was unknown 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 spread to other German ceramic manufacturers and eventually became used throughout Europe.

Hard-paste porcelain is known to be fired at a range of temperatures to create many different end results. Depending on the firing method, hard-paste porcelain can be manufactured to resemble stoneware or earthenware. Generally however, it is not necessary to utilize hard-paste porcelain for such lower temperature ceramics. Hard-paste porcelain can be employed to make porcelain bisque, a hard crystalline product fired at very high temperatures in a pressure controlled environment. This technique produces 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 use hard-paste porcelain simply for this reason, this could include holyrood tea saucer.