In the town of Vietri Sul Mare, local artistic pottery represents one of the most important resources for its inhabitants.
The town is full of potteries where the decorative arts are handed down from generation to generation. Every craftsman has his own technique, his own secrets which make his creations unique and special.
THE ART OF POTTERY
The art of ceramics is the production of objects from earth, forged by hand or by machine, and then fired. The word comes from the Greek for clay and has been adopted by modern languages in same way as the Latins adopted fictilis, i.e to indicate any object made from clay. In its original meaning, still present in many modern languages, “ceramica” includes crockery, statues and statuettes and building materials. Such objects are different from a technical point of view :
- on the basis of the various nature of the earth and the ingredients mixed with it to make the clay, differences which require appropriate temperatures;
- according to the finishing glaze, regarding ornament, and according to the type of decoration. Essential raw materials and clay obtained from mixtures with adequate amounts of water and clay (v), in a natural state or corrected by the addition of other substances, which offer sufficient plasticity and cohesion.
2. The clay mixture
The first crude product, already relatively firm ( called verde),is dried, then it must be fired to contract the clay paste, harden it and fix its permanent form; according to the chemical composition, it is transformed, more or less intensely and the colour is also changed. Unlike that which happens in the glass-making art, it does not melt (this would deform the object); some kinds of ceramics, however, are brought to the point at which vitrification begins. After firing, the clay mixtures can be considered according to the degree of compactness or according to the colour which it has acquired; these results can be used for the first classification of clay pastes since every class of products has its own fundamental characteristics; we therefore have a porous paste, a compact paste, a coloured paste or a white paste. However, the final classification must take another element into consideration, which in most cases is a constituent of a given type of ceramics: i.e. glazing.
The simplest forms of pottery are found in objects made from only paste: i.e. terracotta, literally baked earth, which is also the name given to the first great class of a rational division of production: that is of all items made from fired clay, porous, coloured or unglazed ( from bricks to garden pots, from statuettes to ornamental terracotta). From the earliest times, for practical reasons it was necessary to correct the porous nature of the clay and for aesthetic reasons, the colour of the paste, by applying a coating, more or less thick, transparent or opaque, which made soft pastes impermeable, hard pastes smooth and coloured those pastes which were not white after firing.
Apart from alkaline veneers used by potters in ancient times, and earth slip which was a coating of white earth, ( in Italy known as of Siena or of Vicenza) applied on green and then given a second, impermeable coating, (‘bianchetto’ as it was called and is still called in many potteries in Italy, was used particularly for ceramics decorated with graffiti) the other forms of veneer can be divided into two types: glazing and enamels. The first are transparent and among them a lead based glazing, also called “vetrina” or “cristallina” which is soft and melts at a relatively low temperature; the boracites and feldspatics, known as ‘cover’, are of porcelain since they melt at a higher temperature. The most commonly used enamel, the brilliant white which is made opaque by the addition of tin oxide, is the classic veneer used on maiolic. Both kinds of veneer can be coloured by the addition of metal oxides which together with the necessary solvents can produce different effects according to the temperature and atmosphere ( oxidizing or reducing ) of the kiln.
The painting and decorating is, in most cases, produced using vitrifiable colours derived from oxides. According to the temperature to which they are subjected, the colours are called muffle-furnace colours (to be applied only on veneers : about 600°) and great furnace colours ( to be applied under and inside the veneer : 900° - 970° and over). The ames of the veneers are still vague not only from one language to another, but also in Italian. Those of a vitreous type are commonly called glacure in French; vidriado in Spanish; Glasur in German; glaze in English; terms which in their widest interpretation, do not well fit the definition “invetriatura” which should limit itself to mean coloured enamel veneers (like Robbia: therefore glazed terracotta). The earth slip veneer ( which requires a second metalic coating to make the object impermeable), is known as “ingobbio” in Italy, “bianchetto”, mezzamaiolica ( the name would indicate an intermediate phase between the two tecniques with the addition of a small quantity of tin oxide to enrich it,) is called . engobe in French, englaba in Spanish , Halbamiolika in German , slip in English. If a veneer is applied to common terraccotta (in this case called “biscotto”), the second great class of ceramics is formed, that of faenze, of which the most famous variety is maiolica. The other sub-divisions correspond to the different types of veneer (slip or metallic ,opaque or transparent).
6. Special clays
The use of appropriate clays and special ingredients give us the production of the other great classes of ceramics, such as gres, which has a compact paste, usually coloured (but also white - its opacity distinguishes it from porcelain, which is translucent), fired at a high temperature and may be both veneered or not ; terraglia, which is fired white paste and of varying compactness, therefore requiring a lead based glaze or a coating adapt for the temperature of the firing; porcelain, which is fired at a high temperature, a white paste, compact and requiring a veneer. When it is produced without a veneer, (specially small artistic pieces,) and resembles the grain of marble, the French name, biscuit is used. The collection of crockery for the table and kitchen takes the name “stoviglie”, which indicated the use to which it is put rather than the type of material.
In all cases, in order to fix the veneer and decoration one or more further firings are necessary after the first firing which produces the "biscotto", and then the product may be defined as "finished". Therefore, there are two essential processes in the production of ceramics: the manipulation of the raw material and the firing; it is during this second phase that the changes in state of matter and the progressive chemical reactions which determine the type of ceramics take place. Attempts to classify ceramics have been very laborious but the terminology is still not precise, each glossary being a controversy and without exact comparison in various other languages.
8.Source of original Italian text
Gaetano Ballardini, Maiolica, in: ENCICLOPEDIA ITALIANA DI SCIENZE, LETTERE ED ARTI; Vol. XXI - ROMA; Istituto della Enciclopedia Italiana - 1951 - pagg. 957 - 967