Shopify Safety Shoe SR Slip Resistance ASTM F3445:2021 Schema — Platform A Ceramic Tile + SLS vs Platform B Steel + Glycerol (Both Required for SR Mark), "Oil-Resistant Outsole" Is a Compound Property Not a Slip Test, ASTM F2413 Covers Zero Slip Resistance, European SRC (EN ISO 13287) Is Not US SR-Equivalent

OSHA 29 CFR 1910.136(a) requires that employers ensure each affected employee uses protective footwear "where there is a danger of foot injuries due to falling or rolling objects, or objects piercing the sole, or where such employee's feet are exposed to electrical hazards." The regulation references ASTM F2413 for impact, compression, electrical, and puncture hazards. For slip hazards specifically, OSHA 1910.136 and the General Duty Clause (Section 5(a)(1)) require that workplaces be free of recognized hazards — in practice, this means employers must provide slip-resistant footwear in environments with slippery floors, but OSHA does not mandate ASTM F3445 by name. The National Floor Safety Institute (NFSI) and various OSHA compliance guidelines recommend a minimum SCOF of 0.40 for wet surfaces — which is the ASTM F3445 threshold. In citations involving slip-and-fall incidents, OSHA compliance officers look for whether the employer required and provided slip-resistant footwear and what test evidence was available. A boot with an ASTM F3445 SR marking provides documented evidence that the employer made a performance-based selection, not just a description-based one. Encode footwear.sr_certified to enable compliance documentation in purchasing records — the field value becomes part of the procurement audit trail.

Biomechanics research establishes that the human gait requires a minimum coefficient of friction of approximately 0.15–0.20 on level surfaces during steady walking. However, peak friction demands during heel-strike, turning, and transitions from level to inclined surfaces can reach 0.30–0.50. The ASTM F3445 threshold of 0.40 SCOF was selected to provide a safety margin above peak demands: floors with SCOF below 0.40 under wet conditions have been associated with significantly elevated slip-and-fall rates in epidemiological studies. The threshold is measured as static coefficient of friction (the force required to initiate sliding of the boot on the test surface divided by the normal force), not dynamic kinetic friction (friction during ongoing sliding). Static friction is higher than kinetic friction for most materials — a SCOF of 0.40 corresponds to a boot that requires a shear force equal to 40% of the normal force to begin sliding. This is not the same as the surface SCOF — ASTM F3445 measures the boot-surface system under specific lubricant and surface conditions, not the floor surface in isolation. The National Floor Safety Institute uses a separate floor tribometer (ANSI/NFSI B101.1) for floor surface testing with a different apparatus; floor surface SCOF and boot outsole SCOF are not directly comparable figures.

Yes — tread pattern significantly affects ASTM F3445 Platform A and Platform B performance independent of rubber compound. The mechanism on lubricated surfaces is hydrodynamic: as the boot outsole contacts a liquid-contaminated surface, the liquid must be displaced from the contact area before solid-to-solid friction can develop. Tread patterns with deep channels, wide lugs, and escape grooves allow liquid to flow out from under the contact area, increasing the proportion of the outsole in solid contact with the floor. A boot with a flat (minimal tread) outsole of high-grip rubber compound may perform worse on ASTM F3445 Platform A than a boot with aggressive channel tread in a lower-grip compound, because the flat sole traps SLS solution under the contact patch longer. High-performance slip-resistant outsoles typically combine: a slip-resistant rubber compound (measured SCOF on both F3445 platforms), and a tread pattern designed to evacuate liquid quickly from the contact zone (channels oriented to lead toward the boot edges). Restaurant-grade slip-resistant footwear (brands like Dansko, Shoes for Crews, and Birkenstock Alpro) often use both compound and tread pattern optimization. Encode footwear.tread_pattern as 'aggressive-lug', 'moderate-channel', 'flat-sole', or 'siped' as a supplementary field to footwear.sr_certified — the SR certification is the authoritative claim, but tread pattern data helps buyers understand which environments (standing liquid vs thin film) the boot is optimized for within the SR-passing range.

ASTM F3445-21 applies to any occupational footwear submitted for testing — including clogs, mules, and open-back styles commonly used in food service (chef clogs, kitchen mules). The SR testing procedure measures the outsole material and contact zone friction, not the upper construction or toe coverage. A clog can carry ASTM F3445 SR marking if its outsole passes both Platform A and Platform B. The SR marking on a clog does not address the additional slip risk from an open back (the heel can exit the shoe during walking, creating a stumbling hazard distinct from the outsole friction hazard) — that is a fit and retention concern separate from ASTM F3445. OSHA has issued guidance that open-back clogs in some environments create tripping and foot-retention hazards even with slip-resistant outsoles. ASTM F2413 requires closed toe and heel construction for its protective markings — a clog or sandal cannot carry ASTM F2413 toe protection markings. This creates a split: clogs can be ASTM F3445 SR certified but cannot be ASTM F2413 I75/C75 certified. A food service worker who needs both slip resistance and falling-object toe protection must use a closed-toe boot or shoe that carries both markings. Encode footwear.construction_type as 'closed-toe-closed-heel', 'closed-toe-open-heel' (clog), 'open-toe', or 'boot' — the F2413 markings are only physically possible for closed-toe-closed-heel or boot construction types.

ASTM F3445-21 requires that a manufacturer resubmit footwear for testing under the standard whenever there is a change to the outsole compound formulation, tread pattern geometry, or material composition that could affect friction performance. The standard does not allow a manufacturer to carry forward SR certification from one outsole formulation to a new formulation without retesting — the SR marking is specific to the tested product as submitted. In practice, large footwear manufacturers maintain ASTM F3445 test records for each outsole formulation and update testing when compounds are changed. For buyers, this means the SR marking on a boot sold today is valid for the boot as manufactured today — if the manufacturer later reformulates the outsole compound (which may happen without public announcement as material costs change), the old SR test data no longer describes the new product. In procurement specifications, consider requiring that the supplier provide the ASTM F3445 test report date and the specific product model year or batch for compliance documentation, not just the SR marking. Encode footwear.sr_test_date as the ISO 8601 date of the most recent ASTM F3445 test report for procurement documentation purposes.