Glossary

One of the fundamental characteristics of natural-finish porcelain stoneware is its high resistance to abrasion, meaning the ceramic surface’s resistance to wear caused by contact with the heels of shoes, the feet of furniture, chairs, trolleys, vehicles and even floor cleaning equipment. Due to porcelain stoneware’s outstanding resistance to abrasion, the surface does not wear, so there is no change in its shine or colour, and there are also no care problems.

In the winter months, moisture and low temperatures may be a serious threat to an outdoor paving if it does not have effective drainage. Good quality porcelain stoneware is frostproof because it has excellent resistance to low temperatures: as it is not porous, it absorbs an extremely low percentage of water. Thanks to this characteristic, a stoneware paving can withstand the lowest temperatures with no risk of tile detachment or cracking.

After tiles’ installation, to complete the surface the joints must be filled with a cement-based material, the grout. This protects floor and wall coverings against infiltrations of dirt and liquids of various kinds. Nowadays there is a wide choice of grouts and also of colours for anyone wishing to use the joint to reinforce the aesthetic impact of the ceramic surface.

Ceramic materials have excellent hardness and strength values. The hardness of a ceramic tile or slab is expressed as a number which refers to a mineral included on the Mohs scale. The higher the number, the greater the hardness of the corresponding mineral. Natural finish porcelain stoneware has hardness >6 and as high as 8 points on the Mohs scale, equivalent to that of a gemstone such as topaz. This explains why stoneware tiles are so resistant to scratching.

The joint is the gap, from a few to many millimetres in size, left between one tile and the next during installation to enable normal expansion of the floor covering. This prevents cracking and breakage over the years due to structural and thermal settling of various kinds. Wider joints are used, also for reasons of appearance, for rustic floor coverings or brickwork tiles.

Movement joints in floor coverings are created using special strips which absorb thermal expansion, structural settling, dynamic stresses and traffic vibration, preventing cracks in the flooring or paving. Their use is essential because, by acting as dampers, they are crucial in ensuring the quality and duration of the materials installed.

A tile is classified as “porcelain stoneware” on the basis of its water absorption characteristics (<0.5%). This material’s minimal absorption implies a very low porosity and the complete fusion of the tile body, making this material very similar to a glass. Porcelain stoneware tiles are produced by mixing various raw and other materials which are first milled and then spray-dried prior to pressing.

The grade is the marking applied to every lot of tiles which defines its quality. Boxes are marked with the number 1 for first grade material. First grade material is regulated by standards which set appearance, physical and mechanical parameters which must be exceeded for the award of this classification. Tiles which fail to meet these requirements are downgraded to second or third grade, depending on the severity of the defect found.

In this process, the edges of tiles are trimmed so that they are perfectly straight and perpendicular.Whether or not a tile’s edges have been rectified is a very important factor to be checked at the time of purchase if the intention is to install the material with narrow joints and create a continuous, resin-effect stoneware ceramic surface. With rectified edges, joints as narrow as 2 mm are permissible.

Shade variation is the term used when the surface of a tile is intentionally not uniform in colour and tone. These variations in colour within the same tile collection are used to reproduce textures that evoke natural materials such as stone or marble. In the case of a wood effect, shade variation can provide a distressed, time-worn appearance.

The size refers both to the shape of the tile, which may be square, rectangular, hexagonal or irregular, and the dimensions of the sides, on which basis tiles are classified as small, medium and large size. In general, tiles over 120 cm are defined as large size tiles or ceramic slabs. When choosing the most suitable size, consideration must be given to the type of location, the size of the interior, whether or not there is natural light, its intended use and the desired style.

Normally, when tiles are over 120 cm in size they are defined as ceramic slabs. Apart from their size and appearance, the installation method is also different from that used for smaller tiles. The installation of slabs requires special care, with the use of specific equipment, the right adhesive and the correct adhesive application procedure. Porcelain stoneware slabs are particularly attractive and are being more and more widely used in architectural and interior design projects and in locations where continuity between the floor and wall covering or between different rooms is required.

There are different degrees of slip resistance and different methods for measuring it. The most widely used method is a German test, which awards an R value. The lowest value is R9 and the highest is R13. A higher anti-slip resistance coefficient is obtained during production by adding abrasive particles to the surface glaze, or by the creation of relief textures or ribbing.

Tiles’ surface finish is produced by a variety of different processes depending on the appearance required.The natural finish, for example, is the most widely used and the most versatile.The shine finish, on the other hand, is produced by honing the ceramic surface to create a luxurious “mirror” effect. It is often used on ceramic slabs for a particularly glossy, glassy surface, and to increase their impression of depth.

Through-body porcelain stoneware is a type of stoneware in which the surface colours are the same throughout the entire tile.This means that even if the tile is chipped, a very rare occurrence in good quality products, the damage in terms of appearance is minimal, because there is no difference between the surface and the part underneath.

The tone is the colour shade of a specific production batch of tiles. In the production process, it is virtually impossible to produce pieces that are perfectly identical in terms of colour. Therefore, before packaging tiles are grouped by colour shade and assigned an alphanumerical code which identifies their specific tone.

Tiles’ working size is marked on the packaging and is an important parameter for their correct installation. Tiles leaving the kiln may vary in size by a few millimetres, giving them different working sizes, so during grading they are placed in lots of the same size, within the tolerances set by the standards.