Soft-paste porcelain
Encyclopedia
Ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
material, sometimes referred to simply as "soft paste". The term is used to describe soft porcelains such as bone china
Bone china
Bone china is a type of soft-paste porcelain that is composed of bone ash, feldspathic material and kaolin. It has been defined as ware with a translucent body containing a minimum of 30% of phosphate derived from animal bone and calculated calcium phosphate...
, Seger porcelain, vitreous porcelain, new Sèvres porcelain, Parian porcelain and soft feldspathic porcelain, and is also used more narrowly to describe clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
bodies mixed with glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
frit
Frit
Frit is a ceramic composition that has been fused in a special fusing oven, quenched to form a glass, and granulated. Frits form an important part of the batches used in compounding enamels and ceramic glazes; the purpose of this pre-fusion is to render any soluble and/or toxic components insoluble...
, used mainly in the production of decorative figures and domestic wares in 18th century Europe.
General
The history of soft-paste porcelain dates back to early attempts by European pottersPottery
Pottery is the material from which the potteryware is made, of which major types include earthenware, stoneware and porcelain. The place where such wares are made is also called a pottery . Pottery also refers to the art or craft of the potter or the manufacture of pottery...
to replicate Chinese
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
porcelain at a time when its composition was little understood and its constituent materials were not widely available in the West. The earliest formulations were mixtures of clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
and ground-up glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
(frit
Frit
Frit is a ceramic composition that has been fused in a special fusing oven, quenched to form a glass, and granulated. Frits form an important part of the batches used in compounding enamels and ceramic glazes; the purpose of this pre-fusion is to render any soluble and/or toxic components insoluble...
). Soapstone
Soapstone
Soapstone is a metamorphic rock, a talc-schist. It is largely composed of the mineral talc and is thus rich in magnesium. It is produced by dynamothermal metamorphism and metasomatism, which occurs in the areas where tectonic plates are subducted, changing rocks by heat and pressure, with influx...
and lime
Lime (mineral)
Lime is a general term for calcium-containing inorganic materials, in which carbonates, oxides and hydroxides predominate. Strictly speaking, lime is calcium oxide or calcium hydroxide. It is also the name for a single mineral of the CaO composition, occurring very rarely...
are also known to have been included in some compositions. These wares were not yet true porcelain as they were not hard and vitrified
Vitrification
Vitrification is the transformation of a substance into a glass. Usually, it is achieved by rapidly cooling a liquid through the glass transition. Certain chemical reactions also result in glasses...
by firing kaolin clay at high temperatures. As these early formulations suffered from high pyroplastic deformation, or slumping in the kiln at raised temperature, they were uneconomic to produce and of low quality. Formulations were later developed based on kaolin clay, quartz, feldspars, nepheline syenite and other feldspathic rocks. These were technically superior and continue in production. Soft-paste porcelain is now used more narrowly to describe clay bodies mixed with glass frit.
Medici porcelain
Medici porcelain
Medici porcelain was the first successful attempt in Europe to make imitations of Chinese porcelain, although it didn't managed to make true porcelain. The experimental manufactory housed in the Casino of San Marco in Florence existed between 1575 and 1587 under the patronage of Francesco I de'...
was the first successful attempt in Europe to make imitations of true Chinese porcelain
Chinese porcelain
Chinese ceramic ware shows a continuous development since the pre-dynastic periods, and is one of the most significant forms of Chinese art. China is richly endowed with the raw materials needed for making ceramics. The first types of ceramics were made during the Palaeolithic era...
. Produced between 1575 and 1587 the body is a type of soft-paste porcelain, composed of white clay containing powdered feldspar
Feldspar
Feldspars are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust....
, calcium phosphate
Calcium phosphate
Calcium phosphate is the name given to a family of minerals containing calcium ions together with orthophosphates , metaphosphates or pyrophosphates and occasionally hydrogen or hydroxide ions ....
and wollastonite
Wollastonite
Wollastonite is a calcium inosilicate mineral that may contain small amounts of iron, magnesium, and manganese substituting for calcium. It is usually white. It forms when impure limestone or dolostone is subjected to high temperature and pressure sometimes in the presence of silica-bearing fluids...
(CaSiO3), with quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
.
Other early European soft-paste porcelain, also a frit porcelain, was produced at the Rouen manufactory
Rouen manufactory
The Rouen manufactory was an early French manufactory for faience and soft-paste porcelain, located in Rouen, Normandy.-Soft-paste porcelain :...
in 1673, which was known for this reason as "Porcelaine française". Again, these were developed in an effort to imitate high-valued Chinese hard-paste porcelain
Hard-paste porcelain
Hard-paste porcelain is a ceramic material that was originally made from a compound of the feldspathic rock petuntse and kaolin fired at very high temperature. It was first made in China around the 9th century....
.
As these early formulations suffered from high pyroplastic deformation, or slumping in the kiln at raised temperatures, they were difficult and uneconomic to use in mass. Formulations were later developed based on kaolin (china clay), quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
, feldspar
Feldspar
Feldspars are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust....
s, nepheline syenite
Nepheline syenite
Nephelene syenite is a holocrystalline plutonic rock that consists largely of nepheline and alkali feldspar. The rocks are mostly pale colored, grey or pink, and in general appearance they are not unlike granites, but dark green varieties are also known...
, and other feldspathic rocks. Soft-paste porcelain with these ingredients was technically superior to the traditional soft-paste and these formulations remain in production.
Characteristics
Soft-paste made with little clay is not very plastic and shaping it on the potter's wheel is difficult. Those pastes with more clay (now more commonly referred to as "bodies"), such as electrical porcelain, are extremely plastic and can be shaped by methods such as jolleying and turning. It was called "soft" because of its inability to hold rigid under high temperatures compared to hard-paste porcelainHard-paste porcelain
Hard-paste porcelain is a ceramic material that was originally made from a compound of the feldspathic rock petuntse and kaolin fired at very high temperature. It was first made in China around the 9th century....
. The feldspathic formulations are, however, more resilient and suffer less pyroplastic deformation. Soft-paste is fired at lower temperatures than hard-paste porcelain
Hard-paste porcelain
Hard-paste porcelain is a ceramic material that was originally made from a compound of the feldspathic rock petuntse and kaolin fired at very high temperature. It was first made in China around the 9th century....
, typically around 1100oC for the frit based compositions and 1200 to 1250oC for those using feldspar
Feldspar
Feldspars are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust....
s or nepheline syenite
Nepheline syenite
Nephelene syenite is a holocrystalline plutonic rock that consists largely of nepheline and alkali feldspar. The rocks are mostly pale colored, grey or pink, and in general appearance they are not unlike granites, but dark green varieties are also known...
s as the primary flux
Flux (metallurgy)
In metallurgy, a flux , is a chemical cleaning agent, flowing agent, or purifying agent. Fluxes may have more than one function at a time...
. The lower firing temperature gives artist
Artist
An artist is a person engaged in one or more of any of a broad spectrum of activities related to creating art, practicing the arts and/or demonstrating an art. The common usage in both everyday speech and academic discourse is a practitioner in the visual arts only...
s and manufacturers some benefits, including a wider palette of colours for decoration and reduced fuel consumption. The body of soft-paste is more granular than hard-paste porcelain, less glass being formed in the firing process.
History of its manufacture
Chinese porcelainChinese porcelain
Chinese ceramic ware shows a continuous development since the pre-dynastic periods, and is one of the most significant forms of Chinese art. China is richly endowed with the raw materials needed for making ceramics. The first types of ceramics were made during the Palaeolithic era...
, which arrived in Europe before the 14th century, was much admired and expensive to purchase. Attempts were made to imitate it from the 15th century onwards but its composition was little understood. Its translucency suggested that glass might be an ingredient, so many experiments combined clay with powdered glass (frit
Frit
Frit is a ceramic composition that has been fused in a special fusing oven, quenched to form a glass, and granulated. Frits form an important part of the batches used in compounding enamels and ceramic glazes; the purpose of this pre-fusion is to render any soluble and/or toxic components insoluble...
), including the porcelain made in Florence
Florence
Florence is the capital city of the Italian region of Tuscany and of the province of Florence. It is the most populous city in Tuscany, with approximately 370,000 inhabitants, expanding to over 1.5 million in the metropolitan area....
in the late 16th century under the patronage of the Medicis. In Venice
Venice
Venice is a city in northern Italy which is renowned for the beauty of its setting, its architecture and its artworks. It is the capital of the Veneto region...
there were experiments supposedly using opaque glass alone.
France
Experiments at the Rouen manufactoryRouen manufactory
The Rouen manufactory was an early French manufactory for faience and soft-paste porcelain, located in Rouen, Normandy.-Soft-paste porcelain :...
produced the earliest soft-paste in France, when a 1673 patent was granted to Louis Poterat, but it seems that not much was made. An application for the renewal of the patent in 1694 stated, "the secret was very little used, the petitioners devoting themselves rather to faience-making". Rouen porcelain, which is blue painted, is rare and difficult to identify.
The first important French porcelain was made at the Saint-Cloud factory
Saint-Cloud porcelain
Saint-Cloud porcelain was a type of soft-paste porcelain produced in the French town of Saint-Cloud from the late 17th to the mid 18th century.-Foundation:...
, which was an established maker of faience
Tin-glazing
Tin-glazing is the process of giving ceramic items a tin-based glaze which is white, glossy and opaque, normally applied to red or buff earthenware. The opacity and whiteness of tin glaze make it valued by its ability to decorate with colour....
. In 1702, letters-patent were granted to the family of Pierre Chicaneau, who were said to have improved upon the process discovered by him, and since 1693 to have made porcelain as "perfect as the Chinese". The typical blue-painted Saint-Cloud porcelain, says Honey, "is one of the most distinct and attractive of porcelains, and not the least part of its charm lies in the quality of the material itself. It is rarely of a pure white, but the warm yellowish or ivory tone of the best wares of the period is sympathetic and by no means a shortcoming; and while actually very soft and glassy, it has a firm texture unlike any other. The glaze often shows a fine satin-like pitting of the surface that helps to distinguish it from the brilliant shiny glaze of Mennecy, which is otherwise similar. The heavy build of the pieces is also characteristic and is saved from clumsiness by a finer sense of mass, revealed in the subtly graduated thickness of wall and a delicate shaping of edges."
Louis Henry de Bourbon, prince de Condé established a soft-paste factory on the grounds of his château de Chantilly
Château de Chantilly
The Château de Chantilly is a historic château located in the town of Chantilly, France. It comprises two attached buildings; the Grand Château, destroyed during the French Revolution and rebuilt in the 1870s, and the Petit Château which was built around 1560 for Anne de Montmorency...
in 1730; Chantilly porcelain
Chantilly porcelain
Chantilly porcelain is French soft-paste porcelain produced between 1730 and 1800 by the manufactory of Chantilly in Oise, France.-Foundation:...
continued to be made after his death in 1740..
A soft-paste factory was opened at Mennecy
Mennecy
Mennecy is a commune in the Essonne department in Île-de-France in northern France.Inhabitants of Mennecy are known as Menneçois.-Twin towns:...
by François Barbin in 1750. The Vincennes porcelain factory
Vincennes porcelain
The Vincennes porcelain manufactory was established in 1740 in the disused royal Château de Vincennes, in Vincennes, east of Paris, which was from the start the main market for its wares.-History:...
was established in 1740 under the supervision of Claude-Humbert Gérin, who had previously been employed at Chantilly. The factory moved to larger premises at Sèvres in 1756. A superior soft-paste was developed at Vincennes, whiter and freer of imperfections than any of its French rivals, which put Vincennes/Sèvres porcelain in the leading position in France and throughout the whole of Europe in the second half of the 18th century.
The use of frit in this paste lent it the names "Frittenporzellan" in Germany and "frita" in Spain. In France it was known as "pâte tendre" and in England "soft-paste", perhaps because it does not easily retain its shape in the wet state, or because it tends to slump in the kiln under high temperature, or because the body and the glaze can be easily scratched. (Scratching with a file is a crude way of finding out whether a piece is made of soft-paste or not.)
England
The first soft-paste in England was demonstrated by Thomas Briand to the Royal SocietyRoyal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
in 1742 and is believed to have been based on the Saint-Cloud formula. In 1749, Thomas Frye
Thomas Frye
The Anglo-Irish painter Thomas Frye The Anglo-Irish painter Thomas Frye The Anglo-Irish painter Thomas Frye (c. 1710 – 3 April 1762 best known for his portraits in oil and pastel, including some miniatures and his early mezzotint engravings, was also the patentee of the Bow porcelain factory,...
, a portrait painter, took out a patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....
on a porcelain containing bone ash. This was the first bone china
Bone china
Bone china is a type of soft-paste porcelain that is composed of bone ash, feldspathic material and kaolin. It has been defined as ware with a translucent body containing a minimum of 30% of phosphate derived from animal bone and calculated calcium phosphate...
, subsequently perfected by Josiah Spode
Josiah Spode
Josiah Spode was an English potter and the founder of the English Spode pottery works which became very famous for the quality of its wares. He is often credited with the establishment of blue underglaze transfer printing in Staffordshire in 1781–84, and with the definition and introduction in c...
.
Recipes were closely guarded, as illustrated by the story of Robert Brown, a founding partner in the Lowestoft factory, who is said to have hidden in a barrel in Bow
Bow, London
Bow is an area of London, England, United Kingdom in the London Borough of Tower Hamlets. It is a built-up, mostly residential district located east of Charing Cross, and is a part of the East End.-Bridges at Bowe:...
to observe the mixing of their porcelain.. A partner in Longton Hall referred to "the Art, Secret or Mystery" of porcelain.
In the fifteen years after Briand's demonstration, half a dozen factories were founded in England to made soft-paste table-wares and figures:
- ChelseaChelsea porcelain factoryThe Chelsea porcelain manufactory is the first important porcelain manufactory in England; its earliest soft-paste porcelain, aimed at the aristocratic market—cream jugs in the form of two seated goats—are dated 1745...
1743 - BowBow porcelain factoryThe Bow porcelain factory was an emulative rival of the Chelsea porcelain factory in the manufacture of early soft-paste porcelain in Great Britain...
1745 . - St James's 1748
- Bristol porcelain 1748
- Longton Hall 1750
- DerbyRoyal Crown DerbyThe Royal Crown Derby Porcelain Company is a porcelain manufacturer, based in Derby, England. The company, particularly known for its high-quality bone china, has produced tableware and ornamental items since approximately 1750...
1757 - Lowestoft 1757
Hard-paste porcelain
Hard-paste porcelainHard-paste porcelain
Hard-paste porcelain is a ceramic material that was originally made from a compound of the feldspathic rock petuntse and kaolin fired at very high temperature. It was first made in China around the 9th century....
was successfully produced at Meissen
Meissen porcelain
Meissen porcelain or Meissen china is the first European hard-paste porcelain that was developed from 1708 by Ehrenfried Walther von Tschirnhaus. After his death that October, Johann Friedrich Böttger, continued his work and brought porcelain to the market...
in 1708 by Ehrenfried Walther von Tschirnhaus
Ehrenfried Walther von Tschirnhaus
Ehrenfried Walther von Tschirnhaus was a German mathematician, physicist, physician, and philosopher...
, though Johann Friedrich Böttger
Johann Friedrich Böttger
Johann Friedrich Böttger was a Germanalchemist.He was generally acknowledged as the inventor of European porcelain although more recent sources ascribe this to Ehrenfried Walther von Tschirnhaus...
who continued his work has often been credited with the discovery of this recipe. As the recipe was kept secret, experiments continued elsewhere, mixing glass materials (fused and ground into a frit) with clay or other substances to give whiteness and a degree of plasticity.