Covering Installation Guide / Defects and malfunctions in wall and floor tilings / Surface defects
Surface Defects
This head encompasses all the defects that lead to an impaired appearance or to an optical perception of non-uniformity in the ceramic wall or floor tiling surface with respect to the initial appearance of the ceramic tile before the tile installation.
Excluded are any defects stemming from the manufacturing process, which are eliminated in finished product selection stage. These defects have been extensively dealt with and catalogued in the technical literature and the ceramic technician is usually well acquainted with them. In addition, standard EN 14411 establishes a definition of commercial first quality and the maximum percentage of surface defects that are permitted in first quality (5%). Claims and differences in interpretation may arise in regard to tiles belonging to commercial classes other than first quality, these almost always being due to lack of information on the product supplied as opposed to what the client expects to get.
After from this, therefore, moreover always associated with particular, isolated tiles if they have already been installed, there are two other groups of defects for which the manufacturer is usually directly responsible:
The first group of defects highlights the need to delimit the concept of uniform appearance in tile manufacturing, and to establish to what extent difference in colour, texture, or gloss may be permitted (or may even become an aesthetic objective). That delimitation involves assigning a colour code which, just as the dimensional tolerances, establishes the limits of the variations perceived by the human eye. Depending on the effect sought, the colour code might require the explicit recommendation of mixing tiles from different packing units prior to tile installation.
The second group of defects, despite their diversity, all originate in the unsuitability of the ceramic tile for its intended location, though the method and the materials used in the tile installation may constitute a more or less determining, contributing factor.
The linkage of ceramic tile technical characteristics to the durability of a ceramic tiling is a long-desired of the entire marketing and sales chain, though full achievement still remains a long way off. However, the last 10 years have witnessed an important advance, in qualitative terms, in relating ceramic tile technical characteristics to quite a number of applications or uses, for which good performance over time is minimally assured.
However, the effort made by the technical staff in the tile and adhesives manufacturing sectors, translated into documents and a guide for the selection of the tiling system, has hardly had any repercussion in the ceramic tile sales chain, in the frame of a business policy still overly focused on production and, hence, oriented to price-based competition. When the commercial strategy based on undifferentiated, mass marketing is left behind, the objective of suitability for intended use can no longer be neglected, particularly if it is aspired to install ceramic tile in fields other than housing.
Nor has normative development favoured such a linkage of tile with its intended use, though the available test methods (EN ISO 10545) brings closer the possibility of relating levels of mechanical strength, chemical and stain resistance to requirable performance in a given application.
Now that Mohs hardness has been tossed out, and the test method of resistance to surface abrasion has been questioned, the only possibility left is to relate impairment of appearance as a result of mechanical action or chemical attack to stain resistance, loss of gloss, and the visual perception of deteriorated surface qualities under real conditions of observation (tangential light).
The application of tribology to heterogeneous materials may provide a new test method that will allow parameterisation of mechanical wear and enable this to be related to levels of traffic.
Other groups of defects may be avoided by means of an appropriate combined selection of the tiles and the tile installation method, it sufficing to apply some of the compulsory or optional characteristics set out in EN 14411.
Excluded are any defects stemming from the manufacturing process, which are eliminated in finished product selection stage. These defects have been extensively dealt with and catalogued in the technical literature and the ceramic technician is usually well acquainted with them. In addition, standard EN 14411 establishes a definition of commercial first quality and the maximum percentage of surface defects that are permitted in first quality (5%). Claims and differences in interpretation may arise in regard to tiles belonging to commercial classes other than first quality, these almost always being due to lack of information on the product supplied as opposed to what the client expects to get.
After from this, therefore, moreover always associated with particular, isolated tiles if they have already been installed, there are two other groups of defects for which the manufacturer is usually directly responsible:
- Non-uniformity in the tiling, expressed in visual contrasts caused by changes in shade, texture, or gloss
- Impairment of surface appearance or quality with time, stemming from deterioration of its aesthetic qualities or also non-uniformity, caused by external aggression of a physical or chemical nature
The first group of defects highlights the need to delimit the concept of uniform appearance in tile manufacturing, and to establish to what extent difference in colour, texture, or gloss may be permitted (or may even become an aesthetic objective). That delimitation involves assigning a colour code which, just as the dimensional tolerances, establishes the limits of the variations perceived by the human eye. Depending on the effect sought, the colour code might require the explicit recommendation of mixing tiles from different packing units prior to tile installation.
The second group of defects, despite their diversity, all originate in the unsuitability of the ceramic tile for its intended location, though the method and the materials used in the tile installation may constitute a more or less determining, contributing factor.
The linkage of ceramic tile technical characteristics to the durability of a ceramic tiling is a long-desired of the entire marketing and sales chain, though full achievement still remains a long way off. However, the last 10 years have witnessed an important advance, in qualitative terms, in relating ceramic tile technical characteristics to quite a number of applications or uses, for which good performance over time is minimally assured.
However, the effort made by the technical staff in the tile and adhesives manufacturing sectors, translated into documents and a guide for the selection of the tiling system, has hardly had any repercussion in the ceramic tile sales chain, in the frame of a business policy still overly focused on production and, hence, oriented to price-based competition. When the commercial strategy based on undifferentiated, mass marketing is left behind, the objective of suitability for intended use can no longer be neglected, particularly if it is aspired to install ceramic tile in fields other than housing.
Nor has normative development favoured such a linkage of tile with its intended use, though the available test methods (EN ISO 10545) brings closer the possibility of relating levels of mechanical strength, chemical and stain resistance to requirable performance in a given application.
Now that Mohs hardness has been tossed out, and the test method of resistance to surface abrasion has been questioned, the only possibility left is to relate impairment of appearance as a result of mechanical action or chemical attack to stain resistance, loss of gloss, and the visual perception of deteriorated surface qualities under real conditions of observation (tangential light).
The application of tribology to heterogeneous materials may provide a new test method that will allow parameterisation of mechanical wear and enable this to be related to levels of traffic.
Other groups of defects may be avoided by means of an appropriate combined selection of the tiles and the tile installation method, it sufficing to apply some of the compulsory or optional characteristics set out in EN 14411.
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