Geneva coffee cup demitasse

Bone china

Bone china is a kind of porcelain body initially 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. geneva coffee cup/demitasse may be an example of this procedure.

The initial use of bone ash in ceramics is associated with Thomas Frye in seventeen-forty-eight in which he used it to develop a type of soft-paste porcelain. In Towards the end of the 18th century, Josiah Spode continued with further developments, and subsequently made it popular, by combining it with kaolin, China stone and china clay to compete against the imported Oriental porcelain.

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

The production of bone china commonly involves a 2 stage firing where the first "biscuit" is fired without a glaze at 1280°C (2336°F) giving a semiopaque product and then it is glaze, or glost, fired at a lower heat less than 1080°C (1976°F). geneva coffee cup/demitasse is probably manufactured using this method.

Soft-paste porcelain

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

Its history dates from the initial undertakings by potters from Europe to copy Chinese porcelain by employing concoctions of china clay and ground-up glass or frit; soapstone and lime were also known to have been employed in some compositions. As these first compounds suffered from high pyroplastic collapse, or slumping in the kiln at high temperature, they were not economical to produce. Formulations were later produced based on kaolin, feldspars, quartz, nepheline syenite 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 formulation of the feldspathic rock petuntse and kaolin fired at very high temperature. It was first made in China in about the 9th century.

The secret of its manufacture was unknown in Europe until the early seventeen hundreds, when Böttger of Meissen, Germany discovered the formula. In spite of attempts to keep it secret, the process was used by other German ceramic potteries and eventually became widely known throughout the whole of Europe.

Hard-paste porcelain is known to be fired at a range of temperatures to make a multitude of different end results. Depending on the firing technique, hard-paste porcelain can be made to resemble earthenware or stoneware. But generally, it is unnecessary to utilize hard-paste porcelain for such lower temperature ceramics. Hard-paste porcelain can be employed to manufacture porcelain bisque, a hard crystalline product fired at extremely high temperatures in a pressure controlled environment. This process gives birth to a translucent bright white ceramic. Unlike other bisque ceramics, porcelain bisque is almost impermeable by water, making it unnecessary to glaze the body before painting. Manufacturers such as Hummel, Lladro and Precious Moments use hard-paste porcelain exactly for this reason, this could include geneva coffee cup/demitasse.