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What is Porcelain?

Porcelain derives its present name from old Italian porcellana (cowrie shell) because of its resemblance to the translucent surface of the shell.[1]  Porcelain is a non-organic, non-metallic solid material and is a member of the ceramics material family.  Porcelain is made by the process of forming and/or casting the material and then heating it to very high temperatures for a specified amount of time followed by cooling the material. 

Porcelain "recipes" vary depending upon their application but typically contain Quartz and clay in the form of Kaolin and Petuntse and/or other minerals and materials.  When exposed to high temperatures, the porcelain material turns to glass via a vitrification process.  Vitrification is characteristic for amorphous materials or disordered systems and occurs when bonding between elementary particles (atoms, molecules, forming blocks) becomes higher than a certain threshold value.[1] Thermal fluctuations break the bonds therefore the lower the temperature the higher the degree of connectivity. Because of that amorphous, materials have a characteristic threshold temperature termed glass transition temperature (Tg): below Tg amorphous materials are glassy whereas above Tg they are molten. Via the virtrification process, the resulting poreclain is strong, translucent, but still delicate.

History

Porcelain originated in China. Although proto-porcelain wares exist dating from the Shang Dynasty (16001046 BCE), by the Eastern Han Dynasty period (196220) high firing glazed ceramic wares had developed into porcelain.[3][4] Porcelain manufactured during the Tang Dynasty (618906) was exported to the Islamic world, where it was highly prized.[4].[5]

Producing Porcelain Pieces

Porcelain can be in the form of either liquid, which is often called "slip" or more solid form (similar to a hunk of clay) which is still liquid based but is more firm.  Porcelain slip is typically casted using molds to form their resulting objects.  Porcelain can also be modeled and/or used  in turnings - such as a rotating potters wheel.  Once the porcelain pieces is created, it is either "cleaned" to remove any remaining casting marks (if applicable) and then typically is allowed to dry to help evaporate some of the water wihin the material. 

Once dried, the porcelain object can be glazed or is fired to form a hard material.  The "firing" is typically performed in a kiln or very high temperature oven.  Typical firing temperatures are between 2000F (1200C) to 2700F (1500C) for a set period of time (i.e., possibly several hours).  If the porcelain piece was not glazed, the result material is called bisque, or biscuit.  Once the fired piece is cooled, it can be cleaned again to smooth the surface of the porcelain and/or painted and glazed.  If painting or glazing is performed, typically the piece is fired again to seal the paint or glaze.  Once this porcess is complete, the porcelain piece is typically finished and ready to be used and enjoyed.

Tutorials & Additional Information

The following websites provide tutorials and additional information about porcelain:

porcelain 400 x 60

References

  1. Oxford English Dictionary: "The ceramic material was apparently so named on account of the resemblance of its translucent surface to the nacreous shell of the mollusc. [...] The cowrie was probably originally so named on account of the resemblance of the fissure of its shell to a vulva (it is unclear whether the reference is spec. to the vulva of a sow)."
  2. OED, "China"; An Introduction to Pottery. 2nd edition. Rado P. Institute of Ceramic / Pergamon Press. 1988. Usage of "china" in this sense is inconsistent, & it may be used of other types of ceramics also.
  3. Kelun, Chen (2004). Chinese porcelain: Art, elegance, and appreciation. San Francisco: Long River Press. p. 3. ISBN 9781592650125.
  4. "Porcelain". Columbia Encyclopedia Sixth Edition. 2008. Retrieved 2008-06-27.
  5. Te-k'un, Cheng (1984). Studies in Chinese ceramics. Hong Kong: Chinese University Press. pp. 9293. ISBN 9789622013087.

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