September 11th, 2013
COF or Coefficient Of Friction is related to the traction and slipperiness of a ceramic or porcelain tile. COF is a standardized method to measure the frictional resistance of a walking surface, in this case, tile. The method used for measuring COF of ceramic tile floors changed in 2012, after years of research and with the approval of the accredited national consensus of ANSI or American National Standards Institute.
The new method, known as DCOF Acutest, measures dynamic friction, which is the frictional resistance one pushes against when already in motion. For both SCOF or Static Coefficient Of Friction and DCOF or Dynamic Coefficient Of Friction, a slip occurs when pushing off with more force than the surface can resist.
The new DCOF AcuTest requires a minimum value of 0.42 for ceramic tiles for level interior spaces expected to be walked upon when wet. According to this standard, tiles with a wet DCOF AcuTest value of less than 0.42 are only suitable for areas that will be kept dry. Tiles with a lower minimum wet DCOF AcuTest are not necessarily restricted to dry areas only, but rather are restricted to applications where they are kept dry when walked upon. In the case of residential bathrooms, the common use of bathmats can accomplish this. Similarly, in enteranceways, the use of entrance mats can accomplish the same.
These changes were approved by ANSI in September 2012, however, it is understood that this represents a big change to an established norm. Thus, most tile manufacturers and importers are reporting SCOF and DCOF AcuTest values during the inherent transition needed for the market to switch to the new requirements. The tile industry is targeting for this transitional period to end December 2013, with the new standards in place by January 2014.
Why did this change get made? While DCOF and SCOF are relevant to human abulation, DCOF is more widely used worldwide and arguably relates better to slips occurring while the person is in motion. However, the technology on which the DCOF AcuTest is based on was not available in the United States until recently.