Know Your Basics: Slip-Resistant Shoes. Man showing the bottom of a shoe..

How Is Footwear Tested For Slip Resistance?

Currently the two most recognized test of slip resistance (technically referred to as COF or Coefficient of Friction) are the Brungraber Mark II test and the SATRA test. The basic difference in the two tests is that the Brungraber Mark II test uses a 3" x 3" sample of the outsole, while the SATRA test uses the actual entire outsole. Most footwear designed to be worn in kitchen-type environments are tested on clay quarry tile using a combination of vegetable oil and water on the surface.

How Do I Know How Slip Resistant A Shoe Is?

Slip Resistance (COF) test results can range from 0.0 up to 1.0 with the higher the number the greater amount of traction on the test surfaces. Once the outsole has been tested, be it the 3"x3" sample or the entire outsole, it is assigned a COF number.

What COF Number Should I Look For And What Is The Standard For Slip Resistance (COF)?

If you look at all footwear currently sold in the U.S. that is marked as Slip Resistant, the average test results are about 0.3. Currently ASTM as not established a minimum COF that an outsole must meet to be called “Slip Resistant" but they working on a standard COF for footwear, and the number they are looking at is 0.4 and for that reason, we would recommend 0.4 as the minimum when working in oily and wet conditions.

Final Thoughts:

Slip Resistant is not “Slip Proof" or “Non-Slip" it simply reduces the likelihood that you will slip and become injured when wearing slip resistant footwear in environments similar to those the footwear outsole was tested in.

All slip resistant footwear, regardless of materials, tread pattern or test results, lose much of their integrity once the tread pattern becomes contaminated with dirt, food particles or anything else that can become lodged in the outsole, so cleaning the soles of any slip resistant footwear is extremely important in reducing your risk of slipping or falling.

All of the information included here applies regardless if the footwear contains a protective toe cap (safety toe) or not.