Coefficient of friction (COF) is the measurement of a tile’s frictional resistance, closely related to traction and slipperiness. Both static and dynamic measurements can be taken. Static coefficient of friction (SCOF) is the frictional resistance one pushes against when starting in motion. Dynamic coefficient of friction (DCOF) is the frictional resistance one pushes against when already in motion. For SCOF and DCOF, a slip occurs when pushing off with more force than the surface can resist. That can happen when the angle of the force changes (e.g., pushing off harder while pressing down less) or when the floor surface becomes more slippery than anticipated. What is the DCOF AcuTest? The DCOF AcuTest is an evaluation of the COF of a tile surface under known conditions using a standardized sensor prepared according to a specific protocol. Measurements are made with the BOT- 3000, an automated and portable device that measures DCOF. The ANSI standard A137.1–2012 also allows the use of other equivalent tribometers. Wet measurements use 0.05% sodium lauryl sulfate solution to establish a thin film as would be present when a slip occurs.

The precision, repeatability and reproducibility of the DCOF AcuTest protocol are provided in the A137.1– 2012 standard. The test was so named for easy recognition, and to distinguish it from other DCOF measurements using different instruments and/or protocols. The DCOF AcuTest COF measurement is not a property of the flooring, but rather a measurement of the interaction between the sensor, the lubricant and the tile surface under controlled conditions. It is useful to allow comparison between surfaces or to evaluate how a surface has changed over time. However, while the DCOF AcuTest can provide a useful comparison of tile surfaces, it cannot predict the likelihood a With the portability and ease of the DCOF AcuTest, it’s easy to evaluate ceramic tile in situ. This is particularly useful for determining if tiles have been affected by wear or contaminants.eptember/October 2013 I www.tile-magazine.com 41 person will or will not slip on a tile surface — nor can any other device. Because many variables affect the risk of a slip occurring, the DCOF AcuTest measurement shall not be the only factor in determining the appropriateness of a tile for a particular application.



1. Slip resistance  C.O.F= 0.60

2. Conditionally Slip resistance C.O.F.= 0.50-0.60

3. Questionable C.O.F.= <0.50


PEI 1- Decorative tile, residential and commercial wall and barefoot traffic

PEI 2- Wall and residential bath floor, soft soled traffic

PEI 3- All residential and light commercial floors

PEI 4- Medium commercial and light industrial, institutional, moderate soiling

PEI 5- Heavy traffic, abrasive dirt


V1- Uniform- Minimal to no difference among pieces

V2- Slight- Distinguishable differences in texture and / or pattern within similar colors

V3-Moderate- While the colors present in a single piece of tile will be indicative of the colors to be expected on other tiles, the amount of   colors on each piece may vary significantly

V4- Random- Random color variation from tile to tile, so that one tile may have totally different colors from that on aother tiles. Thus, the final  installation will be totally unique.


0-0.5%- Impervious-Porcelain tiles, frost proof

0.5-3% -Vitreous- Red and White body wall and floor tile, frost resistant

3-7% – Semi-Vitreous- Non- Frost proof red and white body floor tiles

Over 7%- Non- Vitreous-Monoporosa floor and wall tile, double fire wall tiles, and earthenware