Annex A of the NBR 13818 technical standard describes how a visual analysis of the product surface can be performed. The observer must be in a standing position one meter away from the panel made up of the pieces to be evaluated and, with the naked eye, look for defects such as, for example: depressions, stains, spots, protrusions, scratches and cracks, etc.
Intentional effects existing on the surface of the tiles cannot be considered as defects, such as for example, intentional spots and crackling, color movements.
The evaluated pieces cannot contain more than 5% perceptible defects. |
