Page 50 - OHS, January/February 2021

PPE: FOOT PROTECTION
that defifines the safe threshold COF...for all combinations of footwear, contami- nant, and flfloor type,” ASTM F2913 offffers a strong directional guideline for evaluating the effffectiveness of slip-resistant footwear for the workplace and has become the gold standard in determining the dynamic COF of footwear and outsole.4 Here’s ASTM’s de- scription of F2913:
This test method determines the dynamic coefficient of friction be- tween footwear and flooring under reproducible laboratory conditions for evaluating relative slip performance. The method is applicable to all types of footwear, outsole units, heel top lifts and sheet soling materials, also to most types of floorings, including matting and stair nosing, and surface contaminants on the flooring surface, including but not limited to liquid wa- ter, ice, oil and grease.
In the F2913 protocols, COF scores are tested under the following contaminants:
■ Water/Ice
■ Oil
■ Soap/Detergent
■ Grease
■ Combinations of the above
Most notably in F2913, the testing is
conducted on the entire shoe, rather than a swatch or section of the outsole. Meth- ods that don’t test the entire shoe may yield higher scores that do not accurately reflect the performance of the shoe in action. Still, other testing methods generally employ a standardized test foot primarily for evalu- ation of flooring.5
With the advent of ASTM standard F2913, the specific testing of footwear (rath- er than merely floor surfaces) for slip resis- tance brings us closer to a testing protocol that takes those key factors—floor, contam- inants and footwear—into consideration and offers a solid foundation for evaluating the slip resistance of PPE footwear.
ASTM F2913 or the Whole Shoe test provides the most complete approach to evaluating how different footwear materi- als interact with various work surfaces. All slip-resistant footwear should be tested to this standard to establish a common basis for comparison.6
Many safety professionals and manu- facturers rely upon slip scores generated through Mark II Brungraber, also known as ASTM F1677. However, this test was with- drawn by ASTM in 2006 because it only
measures a portion of the outsole and not the whole shoe.7
ASTM F2913 provides better data, though of course it cannot completely quantify the term “slip resistance” or fully ensure safety. As Blanchette and Spiller note, “it is important to establish that no testing, either human subject or mechani- cal, can accurately predict with 100 percent certainty the required level of safety so that slips will not occur.” 8
Reputable slip-resistant footwear man- ufacturers continuously test their footwear and publish their findings, utilizing up-to- date testing standards. A vendor should be able to provide the dynamic COF score of each and every shoe style they produce upon request.
Slip-Resistant Outsole Technology
Genuine slip-resistant footwear focuses on outsole technology and overall shoe design. Slip-resistant outsole technology features design elements including wide heel con- struction for more surface contact, propri- etary compounds for a more powerful grip and a variety of tread patterns for added oil and clog resistance.
Slip-resistant outsoles should be manu-
factured through a process that ensures that the last shoe from the mold is as effec- tive as the first, including:
■ State-of-the-art mold-making tech- nologies such as CnC
■ Thorough mold cleaning to keep molds in tiptop shape
■ Frequent checking and replacing of molds throughout the production process to ensure uniform quality
Recommendations for
Safety Professionals
More and more companies have a safety footwear policy in place as part of their overall safety strategy, but enforcing them effectively does require investment and commitment. Managed programs enhance overall safety by helping to ensure compli- ance and adoption.
Mandated programs require the em- ployer to provide footwear at no charge, which has been proven to ensure compli- ance and reduce slip-related accidents and injuries.9 Providing subsidized or dis- counted footwear to employees is generally accepted to be somewhat less effective than the total workforce coverage of a company- paid, mandated program, but is also offered
46 Occupational Health & Safety | JANUARY/FEBRUARY 2021
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