Double-fired ceramics: sharp colours and patterns
Double-firing is a special technological process that involves firing, first the base of the tile, and then the enamel. This type of tile boasts particularly sharp colours that give full rein to the designer’s imagination thanks to an infinite variety of tints and shades and the chance to create highly complex patterns and effects.
This kind of tile is used mainly for interiors. It adds a touch of class to kitchens, bathrooms and lounges by personalizing the environment and blending perfectly with any architectural features.
Double firing and technical characteristics
"UNI EN 14411 (ISO 13006) - BIII (Appendice L) GL"
Double-fired tiles are obtained by dry-grinding own-quarried clays and fire clays and then mixing, dampening and compacting them in hydraulic presses.
Once the base has been formed it is then quick-cycle fired in roller kilns that reach temperatures of approximately 1100°C.
Once glazed, the product is then sintered in single-layer roller kilns at approximately 1030°C. This creates tiles with an average bending strength of up to 15N/mm2 in compliance with standard UNI EN ISO 10545-4 and a BIII (GL) group classification with a water absorption level of over 10%, in compliance with standard UNI EN 14411.
This class of product hardly shrinks at all during firing, which means its dimensions are extremely consistent and this makes it very easy to lay.
How to lay double-fired tiles
Double-fired tiles can be laid using either cement mortar or tile adhesives.
Under no circumstances should the tiles be wet before laying them with acrylic or vinyl resin-based adhesives or two-component, organic, solvent-based adhesives.
When laying large-size tiles, it is best to adopt the two layer spreading system and, if the floor is very large, incorporate suitable expansion joints which should not be spaced more than 4-5 linear metres apart.
Below are a series of laying conditions that should be avoided as they may cause problems:
When laying tiles on concrete or plaster that is still wet, leave the base to dry for one week per centimetre of thickness.
When laying tiles on brick bases do not spread the tile adhesive more than 4-5 mm thick.
When laying tiles on flexible bases that may generate tile movement (like plaster board, polymer panels, etc.), we recommend using a C2 or D1class tile adhesive that should not be spread more than 2-3 mm thick.
When laying tiles on waterproofed brick surfaces that do not allow humidity to escape, we recommend using a C2 or D1class tile adhesive that should not be spread more than 3 mm thick. Wherever expansion is discharged directly on the tile, always incorporate expansion joints or grouting when laying.