Tiles vary in size, colour, shape, quality and build
Glazed or Unglazed
Glazed Tiles have a surface that is covered by a coloured layer of glaze. This gives tiles important design characteristics (such as colour, texture, decoration, shades of colour etc) and technical characteristics (such as hardness, impermeability to water etc). All these characteristics, both technical and aesthetic, depend on the type of glaze and may vary greatly. Unglazed tiles, on the other hand, are perfectly uniform both in surface and in thickness, and normally have no decoration or patterns.
Red or White body
Depending on the raw materials used, the body of the tiles can be coloured (any colour shade from yellow to reddish brown) or else they can be whitish (sometimes white). In glazed tiles, the colour of the body is relatively unimportant. For certain unglazed tiles, different colours can be obtained by adding colouring pigments.
With a “Vitrified” or “Porous” Body
The body of a tile may be Vitrified (Impervious), otherwise it may contain “pores” that are linked to one another in various ways.An extremely powerful microscope would be required to ‘see’ this characteristic of the body.In order to measure porosity, the quantity of water that is absorbed in given conditions is measured.In other words, water absorption is measured.The higher the water absorption, the more Porous the body, whilst compact Vitrified structures have a low water absorption.
Bicottura (Double Fired)
These tiles have been Fired Twice (at a temperature around 700°C), usually firing the body first, then applying the glaze and marrying the two layers with a second firing,They usually have porous bodies and are suitable mainly for wall tiling.
Monocottura (Single Fired)
These tiles have been Fired Once at a higher temperature (around 1200°C) than bicottura thereby creating a stronger tile which is more suitable for floor tiling, but can also be used for wall tiling.
Rectified Tiles
Tiles that have their edges cut by a diamond cutter or water jet cutter to produce ‘rectified’ edges calibrated to a precise size.The intention is for the tiles to be close jointed providing the customer with the look and appearance of natural stone or marble at a lower price.In many cases the edges of the tile are shaved (arise edges) to prevent damage to the edges.Can be used on walls or floors.
Mosaic Tiles
Mosaic Tiles are small square tiles that are mounted on sheets rather than packed individually.They usually have a mesh backing or a specialised paper facing which assists in the laying process.These tiles require a thin mortar bed and special techniques to be laid successfully.These tiles can be used on walls or floors.
Slim porcelain tiles and panel
Radical new manufacturing processes have evolved over the last 15 years, which have enabled tile manufacturers to produce slim (3 mm to 7 mm) thickness porcelain products in tile formats which range from 300 x 300 mm to 1000 x 1000 mm, to 1600 x 3200 mm giant slim panels of porcelain that can be fixed to innumerable vertical and horizontal, internal and external surfaces. These lightweight, easy to handle materials can be used on building facades, kitchen bench tops or over sound existing floor and wall surfaces. This process can significantly reduce the costs associated with removal of existing tiles and subsequent surface restoration.
Pressed or Extruded
Ceramic tiles can be formed either by pressing or extrusion. Pressed tiles are obtained from a paste that is compacted and formed by a high pressure press. Extruded tiles are formed by passing the raw materials in the form of a paste through a special tube forming a strip of clay which is then cut into tiles.
Glazed Porcelain
These are tiles that have been fired and glazed (the same as normal monocottura tiles) but have a superior vitrified Porcelain Base (body).Their advantage over a glazed monocottura tiles is that the glaze characteristics are usually stronger due to the higher temperature firing that can be used because of the porcelain body base.This usually results in a stronger bond between the glaze and the bisque equating to a stronger impact resistance (chipping) of the tile.Used primarily for floor tiling.
Unglazed Porcelain (Vitrified Tiles)
Extremely dense tiles that commonly have a speckled (granitic) appearance throughout the tile.Are extremely hard wearing and usually used in commercial floor tile applications (shopping centres and foyers of commercial buildings).Are fired at temperatures of up to 1350°C.
Polished Porcelain
Many people talk about porcelain tiles as if they are an alternative to ceramic tiles, when in actual fact porcelain products are ceramic and according to ISO 13006-2013; 4.3.2 – 2(i) classed as group 1a, defined by water absorption of no more than 0.5%. In general terms they are the best, most ideally used ceramic products. Porcelain tiles are widely available for use in commercial and residential environments. Polished Porcelain is unglazed porcelain that is highly polished.Usually comes with bevelled (raised) edges and rectified edges providing uniformity of size allowing for close jointing to create a complete imitation of natural stone (marble).Can be used on both walls and floors.Requires an extremely flat substrate to prevent edges or corners ‘kicking up’. often the use of levelling clips can help achieve a flat lip free installation.
The polishing process may open the micro pores which are present in the tile body. Depending on the raw material particle size and material composition, the abrasive polishing process, by braking out any soft particles, can reveal micro cavities in the surface of the tile. This potentially makes the product more prone to staining and in some instances the surface may require an appropriate ex factory or post installation sealing regime.
Natural (matt) Porcelain
These tiles are unglazed and the surface finish permeates through the entire body of the tile. The tile body is dense and compact. The product is frequently specified for use in areas subjected to high levels of foot traffic. The surface finish can be textured. Matt products are slip resistant and practically impervious.
Quarry Tiles (Extruded tiles)
Quarry Tiles are manufactured by pushing clay under pressure through an extrusion.Due to this manufacturing process, these tiles commonly are thicker and less exact in size than normal (dust pressed) tiles thereby requiring larger grout joints when installed.Extruded tiles are ideally suited to outdoor floor applications.
Cottoforte (Majolica
Cotto’ or ‘terracotta’ is probably the oldest ceramic product. The red (or pink) tile body is usually quite porous and it may be necessary to seal all six sides of the tiles. Terracotta is very durable, and is favoured in external environments. The body is normally formed by pressing, but it may be extruded. Decorated Cottoforte (known as Majolica) is fired once to form the body. A second firing is employed to add decoration.
