TYPES OF CERAMIC TILES

There are various types of ceramic material found in the manufacture of tiles but the most common of these are divided into two major categories – Gres (commonly called Ceramic) and Porcelain. Within the porcelain category there are also a number of types.

Gres / Ceramic

Gres tiles are a type of earthenware, which is porous and needs to be glazed to enable it to be used in areas of high moisture such as bathrooms and kitchens. Ceramic tiles are manufactured from raw clay in both red and white body depending on the origin of the clay. As a general rule, white clay originates from South West England and red clay originates form European countries. These tiles due to being porous, are covered in a glaze which makes them suitable for both wall and floor uses, but the glaze hardness also needs to be checked as this determines a floor tile's suitability to specific environments. Reference should be made to its classification according to the PEI (Porcelain Enamel Institute) test to see if it will withstand the wear encountered in the intended environment.

Porcelain

Porcelain is actually a type of ceramic but is made from a mix of clays and minerals and is fired at a higher temperature than ceramic. The primary characteristics of porcelain tiles are low porosity (water absorption less than 0.5%) and colour that usually penetrates the entire body of the tile. Porcelain tiles are extremely durable due to their low porosity and can be either unglazed, glazed or polished to produce a wide variation of aesthetic effects and performance qualities.

Unglazed Porcelain Through / Full Body - Unglazed porcelain is extremely durable and frost proof and can be produced using different methods to achieve diverse looks, in most cases these methods cause the colouration effect to penetrate the entire body in which case the tile is known as through or full-bodied porcelain. Unglazed tiles can be found with a wide range of different styles dependent on how they are manufactured but the key 

element is that they will generally be very hard wearing. Typically, high quality technical unglazed porcelain tiles are used where high resistance to foot traffic is required (generally matt, lappato or textured) i.e. retail stores, shopping centres, etc.

Polished - Polishing is a technique where unglazed porcelain is polished using fine rollers and results in a 

high gloss finish. Surface polishing whilst providing a very smooth, shiny surface, opens the closed pore structure of the porcelain body and therefore polished porcelains are more susceptible to staining because dirt gets trapped in the opened surface pores. For this reason, particular care must be taken when using a contrasting grout colour with polished porcelain tiles or when selecting a light or lightly patterned tile. Sealants or other pre-surface treatments can prevent this problem as long as routine re-application of the protective treatment is maintained. Polished porcelain tiles can be slippery in wet conditions and are more prone to scratching (particularly evident on plain darker colours). Nowadays however, a lot of polished porcelain is sold pre-sealed but we still recommended that polished porcelain tiles are sealed both before and after grouting regardless.

Glazed Porcelain - With glazed porcelain, a porcelain body is covered in glaze usually for decorative or hardwearing benefit. The glaze provides the decoration and can be marble, stone or any number of different designs. As with glazed ceramic, the glaze hardness resistance determines a tile’s suitability to specific environments and use, and some glazed porcelains should only be used in light or moderate traffic areas. Glazed porcelain tiles intended for floor use should be evaluated based on its PEI (Porcelain Enamel Institute) test classification.

If you are unsure about tile types and finishes for a project, always seek professional advice. It is essential to follow both the manufacturers and your supplier’s recommendations prior to fixing to ensure and achieve a satisfactory result.

PORCELAIN TILE FINISHES

There are a number of different types of finish for porcelain tiles; which you should choose will depend on your budget, how and where you will be using the tiles and also the desired final look.

Unpolished

Unpolished porcelain tiles are produced from clay / raw materials which are mixed into a slurry before being spray dried into a dust then fired at high temperature. Following the firing of the raw materials the tiles are then cooled and packed with no further finishing, the surface being left matt. This finish is often found with full bodied and double or multiple loaded production methods.

Full Body Porcelain - Full body tiles are made from pressing the same coloured dust throughout the whole body of the tile and are therefore usually more expensive to buy than double loaded tiles. This is the traditional way to manufactured unglazed porcelain tiles.

Double Load Porcelain – double load porcelain tiles are a fairly recently technical introduction and have the same material dust throughout and provide the same technical performance but use a neutral colour dust to form the base of the tile and then coloured dust forms the top level. The benefit of this is that using a lower percentage of coloured dust reduces the overall cost of the tiles.

The surface of both full body and double loaded tiles is slip resistant in dry areas and will provide an amount of slip resistance in intermittent wet environments. Special profiles / structures can be added to unpolished porcelain tiles to provide extra slip resistance in wet areas, however they do require more cleaning / maintenance as they have a rougher profile. Unpolished porcelain tiles are also generally rectified.

It is possible to achieve a similar look to these tiles with glazed porcelain tiles, but the glaze is generally unable to provide the resistance to high traffic that an unpolished porcelain tile can. All glazed tiles are subject to the PEI (Porcelain Enamel Institute) wear rating considerations.

Polished

Polished porcelain tiles are polished using small brushes in the same way as natural stone to remove the rough surface and create a smooth, fine finish. They are then often rectified to remove any bevelling on the edges. The surface is usually easy to clean and has an expensive appearance. It is often stronger and needs less maintenance than natural stone however, it can be more prone to scratching and will be slippery in wet conditions. The polishing process will cause the tile to become more porous in some cases although many polished porcelain tiles are now delivered pre-sealed but it is recommended that polished porcelain tiles are sealed both before and after grouting regardless. It is essential to follow both the manufacturers and your supplier’s recommendations prior to fixing.

Lappato (semi-polished)

This finish carried out on glazed porcelain tiles where the surface is given a light buffering to partially but not completely remove the glaze and create a partially shiny, partially matt surface. The finish is not as slippery as a fully polished tile when wet and tends to be more affordable, as less polishing is required. It is currently common practice to use the same colour tile on the wall and floor but to use the Matt finish on the floor and Lappato finish on the walls to give added shine.

Honed

There are 2 different ways of obtaining this finish: either in the press where a specific piece of equipment is required to produce it, or by brushing lightly after the tile has been pressed but before firing. Not only is it stain and scratch resistant and easy to clean but it offers a degree of slip resistance in dry and intermittent wet conditions.

Profiled / Structured

The required profile or structure is pressed into the tile in the wet stage and then fired. The finish is exactly the same as the unpolished one discussed above. The downsides to profiled / structured tiles are that this sort of tile is more difficult to clean as dirt more easily collects in the structure and the surface can be quite rough to walk on, especially for barefoot traffic. It is therefore essential to remove ALL surface grout at the time of fixing. An alternative to profiled or structured tiles where slip resistance is important is by the use of an additive called 

Carborundum. This grit like material can be added to the face of the tile before firing to give the surface a rougher texture thus providing slip resistance, but still allows the tile to be easy to clean.