Coefficient of friction (COF) is a mathematical term used to describe the effect of dragging one substance (shoe sole material) over another (flooring surface).
This coefficient is a measurement of the relative ability of various surfaces to resist the sliding or slipping of the selected material.
The slip-resistance of ceramic tile in ordinary applications is comparable to that of most hard surface flooring materials and it is significantly better than some.
Unglazed tiles have a greater slip-resistance than glazed tiles and are commonly recommended for areas subjected to high water spillage. irregular or textured surfaces can be confused for slip-resistant surfaces. Because a glazed tile is rough or not glossy, doesn’t necessarily mean it is slip-resistant. Even many irregular or textured unglazed tiles can become slippery when wet, allowing surface hydroplaning.
Many glazed and unglazed tiles can feature abrasive grit on their surface, increasing their slip resistance substantially. These tiles are commonly installed in public areas with direct access to the outdoors. Corundum grit surfaces can introduce an element, when traffic acts upon the surface, which will add to the floors deterioration and can be too slip-resistant, when excessive.
Carborundum grit, which appears to be black reflective speckles into the surface of an unglazed tile, will wear flat and become ineffective.
Please Note: that any tile or other hard surface flooring can become slippery when wet or improperly maintained. Slip resistance varies with the many types of footwear, soiling, and cleaning regimen.
Polished wet surfaces give false slip-resistance readings, due to a suction effect developing between the tile surface and sole materials. Even under dry conditions the testing of polished surfaces is questionable.
Avoid trying to raise the COF by using coatings – they will peel, blister, discolour and mar, creating a difficult floor surface to maintain…aside from providing unsatisfactory slip-resistance.