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Classification and Manufacturing of Italian Ceramic tile

Notes

Ceramic tiles are derived from mixtures of clay, sand and other natural materials that are shaped into slabs and fired at high temperatures, up to 1250° C. Their composition is the same as that of all ceramic material, from tableware and sanitary ware to roofing tiles. Like all ceramic material, ceramic tiles are durable, hygienic, non-combustible, fire-resistant, and easy to maintain. Tiles are also rigid and feature relatively low resistance to shock. These features are intrinsic to the nature of ceramic materials.

As floor and wall covering, ceramic tile serves a dual function: an aesthetic function as a design component and a technical function as a finishing building material. As a building material, ceramic tile must be able to withstand a range of environmental stresses. Features defined by international norms govern the technical function of ceramic floor and wall tiles.


1 - Classification and application


According to current international norms (ISO13006), ceramic tiles are classified into 9 groups based on two features: the level of water absorption and the shaping method (see Table 1). This simple classification is warranted given the extremely wide range of products with different trade names and countries of origin. The chosen features are also significant factors in defining the performance specifications of the different products.
As will be discussed later, there are norms and acceptance requirements for standardized characteristics within each group.

Table 1 - Tile technical classification according to ISO

In the new ISO norms (ISO 13006), the group BI is divided in two subgroups: BIa (W.A. < 0,05%) and BIb (< W.A. < 3 %). In addition to the ISO norms, other well-established classification systems (technical and artistic) are still used in trade. Table 2 shows the technical-commercial classification used in Italy.

Most ceramic tiles are shaped by dry-pressing (B groups). About 95 % of tiles produced in Italy are dry-pressed. Their usage can be roughly outlined as follows:

  • Unglazed tiles (clinker, cotto, red stoneware and porcelain stoneware) are used mainly for floors. Clinker and porcelain stoneware have also been successfully used on walls, particularly in exterior applications.
  • Majolica and white body-earthenware are typical materials for tiling indoor walls.
  • Single-fired tiles (red and white body) are generally used for floors. However, in recent years, "monoporosa", a porous single-fired material, has been developed for wall applications.
  • Cottoforte is used for tiling indoor floors and walls.
  • Vitrified, dry-pressed tiles (BI) and extruded tiles, mostly unglazed (clinker and cotto), are used mostly in exterior installations.
This outline demonstrates the range and variety of product types that can be included in the classification of ceramic tile for floors and walls. The range of technical and aesthetic features and of the performances by the different types is vast as well. The performance range in particular has expanded in recent years, thanks to the development of glazed and unglazed products with superior resistance to a variety of environmental stresses. Once relegated to kitchens and baths, ceramic tile is now a viable alternative for any public and industrial application. The versatility of ceramic tile is further enhanced by the almost endless range of colors, textures, and decorative motifs, and by the range of sizes from less than 10 x 10 cm to more than 60 x 60 cm.
Table 2 - Commercial Classification of the Italian Tiles