The 2011 classifications SRA, SRB and SRC were retired under EN ISO 20345:2022 because slip resistance is now treated as a mandatory, pass/fail baseline for every certified safety shoe rather than an optional graded claim, with the SR symbol reserved for a stricter additional test on ceramic tile with glycerine [S2][S3].
SRA previously meant a test on ceramic floor tile wetted with sodium lauryl sulphate (soap solution), SRB meant smooth steel with glycerine, and SRC meant a combined pass on both, and under the 2011 standard a shoe could legally be sold as S1, S2 or S3 with no slip marking at all [S1][S9]. Buyers reading a data sheet therefore had to know whether a blank "S3" meant zero verified grip data, while "SRC" forced one sole compound to compromise between two very different substrates [S6].
What the old SRA, SRB, SRC markings actually tested
Under EN ISO 20345:2011, SRA required a forward flat slip on ceramic tile wetted with a 0.5% sodium lauryl sulphate solution and a heel contact, while SRB used a smooth stainless-steel plate coated with glycerine; only footwear that passed both regimes could carry the SRC combined mark [S1][S6][S9]. The lubrication chemistries, surface roughness and contact mechanics differ enough that a sole compound tuned for SRA would typically underperform on the SRB steel plate and vice versa, so SRC was a forced compromise, not a free upgrade [S6].
The old scheme also allowed a safety shoe to be certified without any slip mark at all, which gave no information to a buyer comparing two S3 boots in a catalog [S2][S4]. Combined with the fact that the 2011 test measured only a flat forward slip, the marking system gave a partial and sometimes misleading picture of real walking biomechanics on contaminated floors [S3].
Why the 2022 revision moved slip resistance to a mandatory test
EN ISO 20345:2022 makes basic slip resistance a baseline requirement of the standard, so a shoe that fails the slip test cannot be placed on the market as EN ISO 20345 safety footwear at all; the only escape is the Ø mark, reserved for special-purpose footwear with spikes, studs or similar elements intended for very specific workplaces such as soft floors with sand, mud or undergrowth [S3][S5].
The test method itself changed in two material ways: the steel plate was replaced by a ceramic tile for the basic test, and a flat forward slip was replaced by a forward heel movement combined with a backward forepart movement, which the standard treats as a closer simulation of how a worker actually loads the foot during a step [S3][S4]. Because basic slip resistance no longer needs a marking, SRA, SRB and SRC as a label set have been removed and the SR symbol is reserved for the additional, optional slip test, performed on ceramic tile with glycerine, that a manufacturer may choose to claim on top of the baseline [S1][S2][S3].
This is the key point for specifiers: a 2022 boot with no slip symbol still had to pass the new ceramic-tile baseline test, and a 2022 boot carrying the SR symbol has additionally passed the glycerine/ceramic test that the industry treats as the harder of the two conditions [S1][S3][S5]. The change kills the design compromise that SRC imposed, because the basic mark and the additional mark now test against the same ceramic substrate rather than forcing a single sole to satisfy both ceramic and steel in one compound [S3][S6].
Side-by-side: 2011 SRA/SRB/SRC vs 2022 SR
The main options line up against four decision criteria. Test substrate: 2011 used ceramic (SRA) or steel (SRB) or both (SRC); 2022 basic test uses ceramic only, with the optional SR still on ceramic [S1][S3]. Lubricant: 2011 used soap solution (SRA) or glycerine (SRB); 2022 basic test uses a soap-type solution on ceramic, while the optional SR uses glycerine on ceramic [S1][S3]. Gait simulated: 2011 measured flat forward slip only; 2022 measures forward heel contact and backward forepart contact to mimic a real step [S3][S4]. Marking logic: 2011 let a shoe ship with S1/S2/S3 and no slip mark, or with SRA, SRB or SRC; 2022 requires basic slip pass to certify at all, and the SR symbol is a separate optional upgrade that a manufacturer can add without forcing a different sole compound to also satisfy a steel-plate test [S2][S3][S5].
The practical upshot: an old SRC boot and a new SR boot are not directly equivalent, because the basic 2022 slip test sits closer to the old SRA in mechanics, and SR sits closer to the old SRB but on ceramic tile rather than steel, so a like-for-like slip comparison needs the substrate detail, not just the letter [S1][S3][S4].
Application mapping: which slip behaviour you actually need
For smooth indoor floors with wet or soapy contamination, typical of food processing and light logistics, the basic 2022 slip test on ceramic is the relevant reference, and SR is not strictly required but adds margin on greasy spillages [S1][S3]. For oily or heavily contaminated industrial floors, the additional SR test on ceramic with glycerine is the harder case and is the one specifiers should look for, because it most closely models the lubricant regime of a machine shop or a vehicle maintenance bay [S1][S3].
For outdoor uneven terrain, profiled outsoles matter more than the slip letter, and the Ø mark is correct for very specific environments such as soft ground with studs where a slip test is not applicable [S1][S3]. PPE buyers who previously asked for "SRC" as a shorthand for "best grip available" should now specify SR explicitly when they want the additional ceramic/glycerine result, and should not assume that absence of a slip mark means absence of slip testing under the 2022 standard [S2][S3][S4].
Transition, documentation, and what to check on a data sheet
EN ISO 20345:2022 is being phased in over a multi-year transition, and both 2011-certified and 2022-certified product may be on the market at the same time, so the standard number printed on the boot, not the presence of any slip letter, is what determines which marking scheme applies [S1][S5]. A 2011 boot still legally carrying SRC has been tested to the older steel-and-ceramic regime, while a 2022 boot carrying SR has been tested to the new ceramic/glycerine additional test, and a 2022 boot with no slip symbol has still passed the new ceramic baseline [S3][S4][S5].
Specifiers and PPE buyers should also be aware of related changes bundled into EN ISO 20345:2022 +A1:2024, including a new SC scuff-cap abrasion test after 1,000 cycles, a new LG ladder-grip test, a revised WPA water-resistance marking that replaces WRU, and split penetration-resistance marks of P (metal), PL (non-metallic, 4.5 mm nail) and PS (non-metallic, 3 mm nail) plus new S6 and S7 waterproof classes [S3][S4][S5]. These are independent of the slip-change rationale but travel with it on the same data sheet, so a slip-spec review is a good moment to re-baseline the whole marking list rather than only the slip line.
For broader PPE spec context across an industrial site, the same risk-based approach is being applied to other categories such as safety footwear compliance under the lighting equipment and electric lamps and lamps and light fittings standards, and footwear fit decisions are increasingly made in parallel with machinery and equipment standards such as construction machinery and equipment, because slip events are a downstream consequence of layout, drainage and housekeeping, not just sole rubber. The signal to watch next is the running-down of 2011 stock through 2026 and 2027 as re-testing to EN ISO 20345:2022 +A1:2024 completes, and any moves by large PPE buyers to drop "SRC" as a procurement shorthand in favour of explicit SR plus substrate notes.
For related coverage, see Why Fuel-Fired Crucible Furnaces Run at 12% Thermal Efficiency.