Are you up-to-date on COF?
September 11th, 2013

New changes in the coefficient of friction requirements are coming in 2014!

Coefficient of friction (COF) requirements for ceramic tile are included in the vast majority of commercial construction specifications for ceramic tile. The standards for COF have changed, and any individual or firm involved in the manufacture, specification, sales, installation, or maintenance of ceramic tile floors should understand the new requirements for tile. COF is the measurement of a tile’s frictional resistance, closely related to traction and slipperiness.

You didn’t know the standard for tile and COF had changed? Perhaps that’s because many manufacturers continued to report COF numbers from the older method (specifically, SCOF values from the ASTM International C1028 test method) along with newly required COF numbers prescribed by the ANSI A137.1-2012 standard for ceramic tile, which mandated this change in test methods. The new test protocol is found in Section 9.6 of the A137.1 standard and is commonly known as the DCOF AcuTestsm.

Starting early in 2014, with the ASTM C1028 method headed for obsolescence, many ceramic tile manufacturers will only report their tile’s COF per the DCOF AcuTest. In addition to the change in test methods, A137.1 now specifies a required DCOF AcuTest value for level interior tiles that will be walked on when wet; the required value is ≥0.42. Previously, there was no required COF value in A137.1 for wet floors, although a minimum SCOF value of 0.6, measured by the ASTM C1028 test method, was commonly specified for ceramic tiles in commercial project specifications.

Does a DCOF AcuTest value of 0.42 represent more or less traction than the old SCOF value of 0.6 per the C1028 test method? While various correlations on average have been established, based on hundreds of tiles and multiple studies, there is no direct relationship between the methods because they measure different physical principles with different wetting agents. In a nutshell, values on individual tiles cannot be correlated between the two methods.

To know definitely if a tile meets the minimum 0.42 DCOF AcuTest criterion, it must be measured.

The technology on which the DCOF AcuTest is based was not available in the United States until recently. The DCOF AcuTest in particular offers several benefits over other methods of measuring COF: it is highly repeatable, it more accurately measures the COF of very smooth surfaces, it correlates well with European measures of COF, and it is portable.

If you haven’t switched yet to specifying/reporting/using/requiring DCOF Acutest values, make the switch today and don’t get left behind.

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