GLOSSARY.

BD15061_.GIF (119 bytes) Calibre When tiles are fired, it is expected that shrinkage rates of the clay particles may vary due to temperature and pressure differences. This can mean that the actual size of a tile which is described as a 300x300mm may in fact be 301.5mm square, or 298.2mm square. To deal with this, tiles from a production run are measured for size electronically and are sorted into groups accordingly. These groups are known as calibres.

 
BD15061_.GIF (119 bytes) Porcelain Porcelain tiles are made from specially selected clays and sands, which are subjected to greater pressures and higher temperatures during production than conventional ceramics. This gives them a very low [less than 0.5 %] water absorption, making them fully frost proof; it also improves the fusion of the glaze to the body of tile and increases its resistance to wear.

Porcelain can either be glazed or unglazed.

Unglazed material can be reminiscent of natural stone, as there is no repeated print or pattern on its surface. Some ranges are also available in highly polished finishes.

 
BD15061_.GIF (119 bytes) Rectified A process by which the edges of a tile are cut after production. There are several benefits :

1 : Each tile should be exactly the same size. [When tiles are fired, it is expected that shrinkage rates of the wet clay particles may vary due to temperature and pressure differences. As a result, tiles from a production run are measured for size electronically and are sorted into groups [known as calibres] accordingly. However, even within these groups there will be a slight variation in dimension, but the rectification process reduces this difference to undetectable levels.]

2: As the tiles do not vary in size, it is easier to plan and design. For example, you can be more certain about setting out, and it is easier to combine colours and be confident in grout joints being aligned [for instance where one colour is used on the wall with another on the floor.]

3: If further tiles are required either due to short measuring or for repairs, the potential problem of new material being a different size is reduced.

In general, only tiles which are 300x300mm or greater tend to be rectified.

 
BD15061_.GIF (119 bytes) Shading As with paint and wallpaper, tiles vary in shade between different batches, and in some cases vary in shade within batches or even boxes.