The History of Ceramics

The history and development of ceramics.

INDEX

1. Ceramics
2. The body
3. Terracotta
4. Coating
5. Painting
6. Special Clays
7. Classification
8. Source


1. Ceramics

Ceramics arts concern the creation of products made of earth, hand moulded o mechanically moulded and fired. The words derives from the Greek name of clay and it is used in modern languages with the meaning of the word fictilis in Latin, indicating any object made of clay. According to this original meaning, maintained in many modern languages, ceramics include crockery, statues and statuettes and building elements. These objects differ in their technical features: 
a) depending on the nature of the earth and of the ingredients that are sometimes added to make the body, as each variety requires a specific temperature; 
b) depending on their coating, on the decorative elements and on the type of decoration. An essential raw material is a body with enough cohesion and plasticity, obtained by the mixture of an adequate amount of water with clay (see), at its natural state or mixed with other substances.  


2. The body

The first greenware, already relatively hardened and then expressly dried, must be exposed to fire, to shrink the earthy body (paste), to harden it and permanently fix it, and according to its chemical composition, it more or less strongly transforms it and changes its colour. Unlike what happens with glass production, a similar art, it does not melt it (as it would deform the product) but, for some kinds of ceramics it leads to a beginning of vitrification. After firing, the body can be considered either according to the different degree of compactness or according to the colour it has taken on. These different results can already be useful for an initial classification of ceramics pastes, because each class of products has its own fundamental characteristics. There are porous or compact paste ceramics and coloured or white paste ceramics. But the final classification must take into account another element that is usually constitutive of a given kind of ceramics: coating.  

 
3. Terracotta
The simplest expression of ceramics are the objects made only of the body: terracotta, that is also the name given to the first big class of a rational division of production, therefore to all the manufactured products of a clay that is porous and coloured when fired and that does not have any coating (from bricks to ordinary garden vases, from statuettes to decorative terracotta). But use requirements and aesthetic feelings suggested since the most ancient times (see further) the adoption of a process to adjust the porosity and change the colour of the paste. This process involves the application of a more or less thick wrapping, either transparent or opaque, that makes soft pastes not waterproof, that polishes the hard ones, and covers with its colour the body of the clays that do not stay white after firing. 
 

4. Coating

Apart from the alcaline coating used by ceramists in the past and the earthy slip, made of a white earth cover (that we call Siena or Vicenza earth), to be applied on greenware and requiring another waterproof wrapping (called “bianchetto” at the time, a term still used in many Italian workshops and used in particular for ceramics to be decorated with graffiti), there are two main types of coatings: paint and glazes. The first are transparent and the lead based one( lead-bearing paint) is also called glaze (vetrina) or crystal and is typical of soft pastes, because it melts at relatively low temperatures: The boraciferous and felspathic ones are called coverings and they are more typical of china, because they melt at higher temperatures. The most common and well-known glaze is the white and shiny one, opacified by stannous oxide, the traditional coating of majolica. Both types can be painted with vitrifiable colours, made of metal oxides that, together with the necessary fluxes, behave differently and lead to different results according to the temperature and to the atmosphere of the kiln (oxidising or reducing atmosphere). 


5. Painting

Painting or colour décor is, in most cases, made of vitrifiable colours produced by these oxides. According to the temperature they must be submitted to, the colours can be called low flame or muffle flame ( to be applied only on coating about 600°) and high fire ( to be applied under the coating and inside it, from 900° to 970° and above). The names of coatings vary not only from language to language, but also in Italian. The vitreous one are usually called in fr. Glacure; sp. Vidriado; germ. Glasur; eng. Glaze, words that do not match the term invetriatura, that should only refer to coloured glaze coatings (like the della Robbia: so terrecotte invetriate- glazed terracotta). The earthy coating ( that needs another metal wrapping to make the object waterproof), that we call “ingobbio” - “bianchetto”, “mezzamaiolica” (this words actually refers to stage in-between the two techniques, the addition of a small amount of stannuous oxide, to make the slip richer) is called in Fr. Engobe, in Span. Englaba, in Germ.Halbamiolika, in Eng. Slip. If a coating is applied to traditional terracotta (called in this case biscotto), the second big class of ceramics is produces, the Faience, the most common of which is majolica. The other types are related to the different kinds of coatings (earthy or metallic, opaque or transparent).
 

6. Special Clays

The use of appropriate clays and of special ingredients allows us to produce other big ceramics classes, such as gres (see); Fr. Grès; sp gres,Ger. Steinzeus, Eng stoneware), that has a compact, usually coloured paste (it can also be white, and then the opaqueness distinguishes it from porcelain, that is translucent), it is fired at high temperatures and can either be coated or not; terraglia (see Fr, Faience fine, terra de pipe, cailloutage; Sp. Loza fine, loza inglesa; ger. Steingut; Engl. Earthenware) that has a white paste when fired and has different stages of compactness, therefore requiring either a lead-bearing paint or a covering according to the temperature; porcellana (see) Fr. Porcelain, Sp. Porcelana; Germ. Porzellan; Eng. Porcelain, china), that is fired at high temperature, has a white, compact paste and needs a covering. When it is produced without a coating (especially in small art objects) and imitates the marble grain it is called, like in French, biscuit (Sp. Bizcocho). All the kitchen and table pottery are called with the collective name stoviglie, a word that indictaes the use, rather than the material (cf. Latin testum, Fr. Poterie; Sp. Vajilla; Eng pottery; Ger.Topferei). 
 

7. Classification 

In all cases to fix the coating and the décor it is necessary to carry out one or two firings after the one necessary to make the biscotto, and only then the product can be considered a finished product. Therefore, there are two essential processes for the production of ceramics: the manipulation of materials and firing: during this last stage, changes in the physical state and the progressive and continuous chemical reactions that fix the kind of ceramics that one wants to produce take place (see what written about the ceramics industry and manufacture). The attempts made to classify ceramics products have been very laborious, but the terminology is still dubious, the single nomenclatures are still debated and the words in different languages do not exactly correspond. The following concise chart shows the most common cases. It has long been adopted by the Museum and by the School of Ceramics in Faenza and without claiming to answer everyone’s needs, it takes into account the two main aspects: the historical and the technical one.