INDEPENDENT LAB TESTS PROVE
THAT SHOES FOR CREWS® IS
THE MOST SLIP-RESISTANT SHOE ON WET / GREASY SURFACES
Soles can be designated as "slip-resistant" if they provide adequate traction on clean, dry surfaces - but most accidents in the work place occur on wet, greasy or greasy/wet surfaces where most of these soles fail.
Our special (patent pending) GRID PATTERN and sole compound is why SHOES FOR CREWS® is Rated #1 for slip-resistance on wet and wet/greasy floors where most employee accidents happen.
About the Test Method
One of the most perplexing questions for our customers is how to compare shoe slip resistance test results from James Machine testing by other shoe companies vs. tests with the Brungraber Mark II by Shoes for Crews. The answer is that any James Machine test of footwear slip resistance is invalid under greasy and/or wet conditions and should not be used to judge the potential performance of a shoe.
Shoes for Crews® uses the Brungraber Mark II for all slip resistance testing because this device is widely recognized by experts in the field and through consensus by the American Society for Testing and Materials (ASTM) as accurate and reliable for not only dry, but also wet or contaminated surfaces. The results which are reported by Shoes for Crews are the results obtained with the Brungraber Mark II according to ASTM F 1677-96.
To the contrary, the James Machine is recognized as providing valid, meaningful footwear slip resistance test results only under dry, non-contaminated conditions. This is because it applies vertical force to the footwear/flooring interface in a first step, which is then followed by gradually increased horizontal force. By contrast, the Brungraber Mark II applies these forces just as the human foot does during walking -- simultaneously -- and is therefore able to accurately and reliably determine the propensity for footwear to slip or plane across the surface of oily and/or water-based contaminants. With its time delay, the James Machine achieves unrealistic footwear/floor contact before applying horizontal force and therefore provides test results that are much higher than reality and are, therefore, invalid. This limitation and restriction of the James Machine to dry, non-contaminated conditions, has been recognized by expert consensus in ASTM F 489-96.
As to the safety zone of approximately 0.25 indicated in our slip resistance charts, this is derived from the considerable body of research into the magnitude of the horizontal (H) and vertical (V) forces which are applied by the human foot during walking and must therefore be counteracted by the measured shoe/floor frictional forces. Both U.S. and European research has shown that the value of the ratio H/V for persons walking normally is at least approximately 0.25, higher for people who are taking longer strides, walking faster, of disabled. Footwear with slip resistance determined by ASTM F 1677-96 to be below this zone is liable to failure to prevent slipping.
We hope this helps you to understand the important differences between these two types of slip resistance test instruments. Please send any further questions on this or any other subject to Dr. Cockrell via e-mail at email@example.com.