The ancient Chinese discovered the art of manufacturing “Porcelain”, a type of ceramic which became a much sought-after commodity of that era. The translucent, glossy characteristics of these products were compared to the surface of common sea shells, referred to as “Porcellana” by the Italians, from which the name Porcelain was derived.

By Nandaka Jayasinghe

Throughout the years, the process of manufacturing porcelain has improved and diversified, resulting in a variety of products, ranging from expensive commodities to essential products in various fields. The physical characteristics of porcelain such as its strength, hardness, resistivity to chemicals combined with its translucent quality have made it the ideal material for the production of wall and floor tiles.

The production of porcelain tiles involves firing the raw materials for much longer and to a much higher temperature than other ceramics. This results in the porcelain being stronger than ceramics and harder than granite. Pigments may be mixed in with the raw materials to obtain various colours and effects. Such tiles are referred to as “homogenous” or “through body” tiles. The benefit of using these tiles is that even if the tile surface gets chipped or scratched, the damage does not stand out as the surface and the rest of the tile body are the same. These tiles are used on surfaces where the high wear and tear may occur, while the surface of these tiles are slip resistant.

Different finishes can be obtained through “powder charging”,  the process where the unfired tile body is suspended in an aqueous solution and metal salts are allowed to penetrate. As the tile is fired, the metal oxides react with the porcelain resulting in various colours. In the process of “double charging”, a very thin layer of porcelain is infused with pigments pressed to the base porcelain layer under high pressure and is then fired. Tiles manufactured using this process can emulate natural stone.

Polished and semi-polished finishes can also be achieved on unglazed porcelain tiles. The need for such surfaces arise due to functional and aesthetic reasons.

In order to achieve more complex finishes, various other methods of surface applications are adopted. These applications could result in prints which are as simple as a monotonous colour or as complex as an organic pattern found in nature. It is also common for tile manufacturers to introduce pigments to the tiles body to help match the colour to its surface. This helps reduce the visibility of surface damages. Such tiles are referred to as “printed tiles” and are used on surfaces which do not undergo heavy wear and tear. However, it is noteworthy that certain printing techniques used today ensure that the top surface of the tile is hardy enough to be used in high traffic areas.

Porcelain tiles have a very low level of porosity, making them the ideal choice for surfaces which demand a high level of hygiene

In order to achieve a highly gloss finish with depth, tiles are applied with a special coating and fired for a second time which creates a shinny, clear coat on the top surface. Such tiles are referred to as “glazed tiles”. While the glazing acts as a protective coat for the tile’s top surface, it is susceptible to damage, as a result these tiles are specified for surfaces which do not undergo heavy wear and tear. However the specula finish of the surface makes it easy to maintain.

Porcelain tiles have a very low level of porosity, making them the ideal choice for surfaces which demand a high level of hygiene. Porosity is a key factor which helps in the bonding process between tiles and the bonding agent used to bond tiles to a surface. As the porosity of a tile reduces, standard bonding agents such as standard cement mortar (commonly used in Sri Lanka) tend to fail. It is important to use an appropriate tile adhesive when working with porcelain tiles.

In order to select the most appropriate type of tiles for a floor the following parameters should be considered.

1. PEI rating – rates a tile’s ability to withstand the wear of foot traffic

2. Moh’s scale – determines how easily a tile gets scratched

3. Water absorption – indicates the tiles porosity

4. Resistance to impact – brittle tiles are difficult to handle and result in breakage during construction and damage during usage

5. Chemical resistance

6. Shape and dimensions

7. Aesthetics

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