MOHS SCALE
To give the consumers an idea of what the scratch resistance of tiles is, the manufacturers sometimes use the MOHS Hardness Scale as per chart beside. Glazed porcelain is normally rated as grade 7 on this scale. However PEI is a more reliable, testable and measurable system.
OPTICAL HAZING
When light rays reflect on a smooth surface like a mirror or a body of water, the light will reflect in a linear, predictable way. While the surface of Polished Porcelain is highly glossy, it does not reflect light in the same way as a mirror does. In some lighting conditions variations in the reflective properties may be noticeable. This is known as Optical Hazing and is an inherent characteristic of polished porcelains.
PEI
Standing for Porcelain Enamel Institute, PEI ratings help you determine the hardness and durability of tiles. Tiles that experiences heavy foot traffic should be harder and denser than tiles that receives lighter foot traffic. Tiles installed on a wall receive no foot traffic and for this reason experience almost no wear. As such, this type of tile can be thinner and provide less friction, since safety is not a concern.
DCOF measures slip resistance during motion while COF measure slip resistance to put an object in motion. This means the new standard measures a surface’s slip resistance more accurately. The Dynamic Coefficient of Friction testing standard is always conducted with a wet, slightly soapy solution of .05% Sodium Laurel Sulfate and Water. That is why there is only one score, and not a wet and dry score like the old standard. Unlike COF testing, the new DCOF test is more accurate and can be conducted in the field with a portable machine called the BOT3000. DCOF values of a surface will change over time. Understanding a material’s abrasion resistance and overall strength will help predict the durability of the finish.
R-rating -DIN 51130- is a shod foot test which uses oil as a contaminant. These results are interpretated into 5 groups, R9 to R13, R9 being the slipperiest and R13 the least. R9 is not suitable for areas requiring slip resistance.
ABC rating -DIN 512097- is a wet barefoot test where a soap solution is applied as a contaminant and the results are placed into 3 classes: Class A dry areas, dry barefoot corridors; Class B every area in class A plus pools surrounds, communal showers, pool beach areas, wet change areas; Class C is comprised of Class A and Class B areas plus pool surround inclines, walk through pools, jacuzzi floors and seats, inclined pool edges and step.
The wet pendulum slip test classifies the slip rating of surfaces with water contamination. It is tested using a Pendulum friction tester. The British Pendulum Number -BPN- is the individual measurement. A minimum of 5 specimens must be tested and the average of those is the Slip Resistance Value -SRV-. The slider number used for the test must be clearly specified. The table in front is the classification of the P-rating.
V-Rate Shade Variation
The V-rate is an important factor to identify the level of shade variation from tile to tile, to evaluate the overall effect of the final installation of the tiles. It has 4 different level of variation as shown by the picture.
