Musealization of the Tribano tower
Cataloguing of ceramic artifacts of Venetian production found in the Adige River between the 13th and the 18th centuries
Audio guide
Ceramics
The term ceramics (from the Greek kéramos = clay, pottery) refers to any product obtained by shaping a clay-based mixture that is then fired in order to be transformed into an object for practical or ornamental use. The discovery of ceramics dates back to the Neolithic period, when humankind, already familiar with fire, became herders and farmers and organized itself into the first villages. Since then, ceramics have accompanied human history, being present in all cultures and in every part of the world.
Clay, a product of the alteration of primary rocks, is abundant in nature and easy to obtain. Its chemical and physical characteristics make it an extremely plastic and moldable material, ideal for producing a very wide range of shapes and therefore of different objects. Through firing, the shape is permanently fixed, resulting in an inert material of a certain fragility, yet resistant to chemical and atmospheric agents, and therefore not easily perishable, unlike objects of organic origin (wood, leather, etc.), nor subject to corrosion like metals. For this reason, ceramics have always found very wide use in everyday life since their discovery. Whether used as a tool or as an object of artistic or religious expression, their presence in human settlements constitutes an important, sometimes essential, source of documentation for studying, understanding, and interpreting the customs, living conditions, and cultural and technological level of a civilization.
The art of the potter
At the basis of ceramic production is clay. This material is extracted from quarries or collected near rivers, where it is deposited as a result of the flow of muddy waters, and is then subjected to treatments that make it workable. Mixed with water in suitable basins, it is left to settle and then sieved to remove impurities; after being left to dry until it reaches an appropriate plastic consistency, it is carefully pounded and kneaded to eliminate air bubbles and make it homogeneous and moldable. If necessary, it is mixed with suitable tempering agents such as sand or marble powder to improve workability and reduce shrinkage during the drying phase.
The shaping of objects can be carried out in different ways: by hand, on the potter’s wheel, or using molds. Starting from a ball of clay, coils can be prepared which, overlapped in rings or wound in a spiral, are then pressed by hand to obtain a continuous surface in the desired shape and size (the coil-building technique, used since prehistoric times).
The ball of clay is made to rotate at high speed on the upper disk of the wheel (whose existence is documented as early as the Mesopotamian civilizations and the Indus Valley more than 5,000 years ago), operated by the potter’s foot. With his hands, the potter pulls up the vessel into the desired shape, characterized by perfect symmetry and uniform thickness. The piece is detached by passing a wire between the base of the object and the work surface, and then left to dry. Subsequently, finishing operations are carried out, and handles, spouts, or other separately formed details may be added, along with any decorations applied while the clay is still unfired.
Using molds, various objects can be mass-produced by pressing plastic clay into specially prepared and reusable plaster forms.
Once subjected to slow drying in suitable environments, to prevent excessively rapid shrinkage that could cause deformation and breakage, the pieces are stacked in appropriate kilns, where firing at 800–900 °C ensures the characteristics typical of terracotta.
Especially for containers, the characteristic porosity of the body can be eliminated through glazing, following a process developed in the Middle East and spread throughout northern Italy starting in the first centuries after the year 1000.
The process is carried out on the biscuit, that is, the piece already subjected to a first firing, which is dipped into an aqueous suspension of very fine powder based on lead oxide and silica sand, allowing it to adhere to the surface. With a second and final firing, the powder melts, forming a thin, glossy, transparent vitreous layer that is perfectly adherent, durable, and impermeable. The glaze can be colored by adding mineral-based pigments to the base composition, such as iron yellow obtained from rust (that from ship anchors was preferred) and copper green based on copper oxide.
A qualitatively superior result with better chromatic rendering was achieved with the introduction of the slip-coating technique (ingobbiatura). This consists of immersing the dried object in an emulsion of light-colored clay (Vicenza earth), so as to leave a thin and uniform layer called slip, which covers imperfections and reduces surface porosity, making it particularly suitable for receiving subsequent painted decorations.
On the slip-coated surface, fine incisions can also be made or parts of the surface removed, revealing the color of the underlying clay with a remarkable aesthetic effect, according to the so-called sgraffito technique. This method was widely used in northern Italy, particularly in Veneto and Emilia-Romagna, from the late 14th century through the entire 17th century and beyond. After the first firing, painted decorations using metallic oxides are applied to the slip-coated surface, whether incised or not. To the original pigments of copper green and iron yellow were added manganese, producing tones ranging from black to deep brown and violet, cobalt blue, and antimony yellow. Slip-coated, painted, and glazed ceramics are also known as half-majolica.
The term majolica is reserved for ceramic products in which the glaze is made opaque by the addition of tin oxide, giving the surface a milky white appearance (enamel), ideal for receiving very fine painted decorations.
As in various parts of the Veneto region, the presence of scudelari (bowl makers) and bocalari (jug makers) is also documented in our area as early as the Middle Ages, as demonstrated by various finds discovered during excavations or in watercourses.
All the ceramics exhibited belong to a private collection.
Luigi Polo
