CERAMICS. – A generic term designating every product obtained through the successive application of two technical processes: 1) the manipulation of more or less plastic clays, possibly combined with other ingredients, for the purpose of shaping by hand or machine objects of utility or adornment; 2) the firing of such artefacts after their drying, at a suitable temperature in a specialized kiln. Ceramics encompasses the execution of these processes, which vary in nature (and in specific name) according to the different kinds of artefacts produced (terracotta, faience, majolica, earthenware, stoneware, porcelain, refractories, etc.), depending on the materials used and the techniques employed (firing temperatures ranging from approximately 850° to 1410°, according to the type).
The origins of ceramics are certain in the Neolithic period, originally deriving from primitive plectogenic techniques. Indeed, a wicker basket lined internally with a clay paste softened by water, after its separation from such an envelope due to the natural contraction of the clay, gave rise to a freestanding vessel. This vessel, initially hardened in the sun and later, in a more advanced stage, in the fire, became, through its successive practical and aesthetic transformations, both a tool and an index of the progress of civilization.
In this way, the original ovoid form of the vessel also gave rise to the "impressed" ornamentation, evenly distributed over the outer surface of the object. This ornamentation was later replaced by painted vase decoration through the use of more refined clays, colouring pigments, and the more or less intense return of ornamental motifs.
The indestructibility of fired clay, even under the dissolving action of subsoil agents, makes the artefact a frequent, often unique, witness to the ways of life of the most remote ages, while the natural stratification of sherd deposits provides irreplaceable chronological reference points. If in geometric style and the primitive schematizations of ornamentation one may intuit expressions with a cosmological content, the floral and zoomorphic elements introduced into the painted decoration of Bronze Age artefacts attest to the beginnings of the aesthetic exploration of nature. The Elamite-Babylonian world, the Pharaonic world, and the Aegean world present particular manifestations in which the invention of the potter’s wheel brought about the refinement of rounded forms, while the contemporary application of the kiln (already in use in the second millennium B.C.) made possible the uniformity of firing and subsequently enabled the development of specific chromatic techniques based on variations introduced into the atmosphere of the firing chamber (oxidizing, neutral, reducing).
The potter’s wheel is mentioned in various significant ways by ancient writers: from the famous passage in Homer concerning the "wheel," to repeated biblical references as moral admonitions; and progressively in classical literature, the reference to this art—which truly creates form from the shapeless—assumes vivid, satirical, and, in general, lifelike values.
The discovery of how to give the surface of a vessel a coating impermeable to liquids represents a new phase in technical progress and adds to the practicality of everyday use a fundamental element for aesthetic enjoyment: colour. It can be immediately affirmed, for example, that the Eighteenth Dynasty of Egypt, which produced coloured glasses for coating its ceramics, gave examples of a chromatic richness and delicacy of hues rarely surpassed—a technique that would endure for millennia and shine again in Hellenistic workshops, later being transmitted, under conditions suited to new times, to the potters of Muslim Egypt and thus to the modern world. Muslim potters, by spreading the use of metallic lustre (improperly called "reflection" by some), achieved effects of superior beauty.
Greek potters, in their two successive techniques of vase ornamentation—"black-figure" and "red-figure"—emphasized the linearity of an impeccable line, not only in decorative and animal motifs but also in the representation of the human figure. Thus, in the workshops of the 5th and 4th centuries B.C., they made the human figure the focal point of decoration, demonstrating unparalleled artistic skill. The Roman world preferred solid ceramics with a "coral-red" patina, delicately decorated in the finest pieces according to Alexandrian taste with relief applications ("terra sigillata"). In this genre, between the 1st century B.C. and the 1st century A.D., "Arretine ware" is characteristic, though this technique soon spread to the provinces, especially in Gaul, where it later supplanted the imported model.
Byzantine influences brought to the lands of the western Mediterranean a form of production characterized by both graffito decoration and austere dichromatic painting in dark purple and green, provided with a vitreous lead-based glaze—a remnant of older workshops—while the use of tin-glaze, also of distant Eastern origin, became increasingly consolidated in the West, as in Moorish Spain, in the centuries following the year 1000. By the end of the 15th century, and even more so in the 16th, it became the foundation of the exquisite polychrome paintings by Italian Renaissance craftsmen, inspired by mythological and sacred "stories," the compositions of Italian and German woodcutters and engravers, and painters, particularly of the Raphaelite school.
This glaze, in the workshops of the della Robbia family, became the precious foundation of the white and blue of those exquisite sacred compositions, and in the workshops of the potters and vase-makers, especially in Romagna, Tuscany, the Marches, and Umbria, it was the first step toward the predominance of Italian art in the pottery of Western and Central Europe. It is therefore no surprise that by the end of the 16th century in France, and after France in all civilized languages, the word *faïence* (from the Romagna city of Faenza, already a centre of a constantly renewed tradition of decorative elements on "majolica" and the birthplace of active and enterprising masters) came to designate a variety of ceramic production that in Italy is more commonly called *majolica* (q.v.) from the name of Majorca, an island of the Balearics, once an active emporium for the importation into Italy of lustre ceramics from the Spanish Levant.
The Far East, through the use of feldspathic clays requiring high temperatures, anticipated every other region in the production of hard pastes and thus of porcelain. The West became so enamoured of it that even alchemists set about trying to uncover its secret, until in Italy, first and especially in Florence, after initial unsuccessful attempts elsewhere, under the patronage of Francesco de’ Medici (1575–85), a "soft" (non-kaolinitic) variety called the "Medici porcelain" was produced, of which rare examples remain.
The German alchemist J. F. Böttger, between 1709 and 1710, finally used Saxon kaolin to produce the first samples of hard European porcelain, establishing the first workshop in Meissen, which was soon imitated despite prohibitions and strictures. Venice already had the Vezzi factory in 1720, while in 1735 the Ginori factory was founded in Doccia, which still operates to the glory of Italy; and in 1743 the royal factory of Capodimonte (Naples) was established, followed in due course by others throughout Europe (q.V. PORCELAIN).
Ceramics – Tiles with cuenca and metallic lustre bearing the emblems of the Nasrids of Granada (14th century).
Towards the end of the 18th century the practical spirit of the British, perfecting white clays that were easily plastic and suitable, even though primarily intended for domestic uses, to receive painted and relief decorations, introduced earthenware, making it a field of intense universal commerce, which then spread to every other country in an ever-growing and even profitable manner. The Germans in Cologne had been producing artistic stoneware since about 1540; a technique that was later practised in other places in the Rhineland.
Entirely recent is the study and achievement of other high-temperature mixtures for particular industrial, technical and sanitary needs; this has opened new fields to a more thorough technological and scientific study of production.
Of interest is the dispute which, starting from more or less solid etymological bases, has divided and continues to divide the field of scholars regarding the development to be given to the content of the word “c.” and hence concerning its definition.
In any case it is possible to group ceramics into porous-body ceramics and compact-body ceramics. Porous-body ceramics include terracotta, faience and soft-paste earthenware; compact-body ceramics include hard-paste earthenware, stoneware and porcelain. Here are their definitions.
Terracotta: a marly mixture, more or less refined; yields products strongly coloured by iron oxide and porous, generally without coating.
Faience: a clay-based mixture; yields porous products, more or less coloured, with a transparent lead-silica coating (marzacotto, cristallina or glassy slip) applied to the piece once it has been fired. This variety is called maiolica when it is covered by an opaque covering, generally white and based on tin oxide (tin enamel). If the coating consists of a thin layer of white clay (Vicenza clay, Siena clay) called engobe, to be applied to the unfired piece, a lower-quality variety is obtained (engobed faience, bianchetto) which, when painted, is covered with cristallina in a single firing.
Earthenware: a clay-, kaolin-, quartz- and feldspar-based mixture; yields white, sonorous, opaque products with a lead-silica coating (glaze), more or less hard (soft-paste earthenware, hard-paste earthenware, according to the proportions of the ingredients and the degree of firing).
Stoneware: a clay- and feldspar-based mixture; yields brown or greyish products, more or less vitrified, opaque, sonorous and hard (those with an alkaline cover obtained with sodium chloride are called salt-glazed stoneware). A variety with a light-coloured paste is also used for artistic purposes.
Porcelain: a kaolin-, quartz- and feldspar-based mixture; yields products with a white, homogeneous, sonorous, hard, impermeable paste, more or less translucent, with a feldspathic cover (those without coating are called French biscuit).
There are then various ceramic products: refractories, steatite, blinker, dental porcelain, abrasives, etc. See Plates LXXX–LXXXI.