Joints with Low Filling

Visualisation

The tile-to-tile joints display an excessive concavity or sinking with respect to the tile plane, in addition to irregularities and, sometimes, changes of colour.

Defect assignment

American tile fixers have instructions in place regarding the grout joint finish, which envisage a maximum concavity that, in the case of reactive resin grouts, lies between 1.2 and 1.6 mm for joints between 6 and 10 mm wide. This slight concavity contributes to the texturing of the wall tiling or flooring and, in the latter, also to the anti-slip capacity of the flooring, favouring the evacuation of the water through the joints.

When the mix contains more water than indicated by the manufacturer, the elimination of this surplus water by evaporation will cause excessive sinking of the material, which will frequently not be uniform either, producing an ugly effect.

The same finish may also result if premature cleaning takes place after the grouting operation. If the material is still fresh or a soft sponge is used, grouting material may be pulled from the joint with the ensuing non-uniform emptying. To avoid this defect it is vital to use an appropriate sponge. In addition, the wet cleaning operation should always be performed diagonally to the joint layout.

Prevention

To avoid this defect:

• Use well-wrung-out quality sponges, of medium stiffness
• Always clean diagonally with regard to the joint pattern
• Make sure that the grout surface has hardened (does not stain the fingers and loses gloss), before starting the cleaning operation
• Observe the mixture proportion indicated by the manufacturer