- Legacy Method: ASTM D-2047 — static COF, dry, James Machine, polish-coated flooring scope
- Current Method: ANSI A326.3 — dynamic COF, tested wet with SBR sensor and SLS solution
- Interior Wet Criterion: wet DCOF 0.42 or greater for level interior floors walked on when wet
- A326.3-2021 Classifications:
- – Interior, wet plus: 0.50 minimum
- – Exterior, wet: 0.55 minimum
- – Oils and greases: 0.55 minimum
- Conversion: None — SCOF and DCOF values are not arithmetically convertible
- Lineage: NFSI B101 series (wet SCOF/DCOF) preceded A326.3; ANSI A137.1 carried 0.42 into the 2012 IBC
- Texture Systems:
- – Poly-Crete SLB / MDB aggregate broadcast
- – Ucrete UD 200 SR slip-resistant grade
- – Smooth self-levelers for dry zones
- Verification: Sample panels and on-site tribometer testing against the declared use classification
- Spec Review: Legacy SCOF lines re-scoped to current A326.3 exposure classes
- Crews: In-house W-2 crews mobilize nationwide — since 1999
- Credentials: Sika Certified + Authorized Sherwin-Williams High Performance Flooring installer
Phone: +1 (844) 687-1961
The SCOF vs DCOF question usually starts with a document, not a floor. A specification written years ago calls for a static coefficient of friction (SCOF) of 0.5 or 0.6, often citing ASTM D-2047, while every current product datasheet answers in a different unit: dynamic coefficient of friction (DCOF), measured wet, under ANSI A326.3. The two numbers are not the same measurement taken two ways. SCOF records the force needed to start motion on a dry surface; wet DCOF records resistance to motion already underway on a wet one. No conversion factor relates them, and a passing static number says nothing about whether the same floor meets today’s wet dynamic criterion.
That gap matters most in facilities where floors run wet by design — commercial kitchens, food processing lines, washdown areas. Slips happen dynamically, on wet contaminated surfaces, which is the condition the old dry static test never measured. This page covers what each method actually tests, why the profession migrated, and how to re-read a legacy slip-resistance requirement when the spec is old and the floor is new.
What Each Test Method Actually Measures
ASTM D-2047 — Static Friction, Dry Surface, James Machine
ASTM D-2047 measures the static coefficient of friction of polish-coated flooring surfaces using the James Machine, a bench apparatus that records the force required to initiate sliding. The method runs dry only, and ASTM’s own scope language restricts the 0.5 compliance criterion to polish-coated surfaces tested on this machine, with experiential data behind it dating to 1942. Two limits follow. The criterion was never written for resinous industrial floors, and it says nothing about wet performance. A “SCOF 0.6 per D-2047” line in an old spec borrowed a polish-industry benchmark for a category the method was not built to govern.
ANSI A326.3 — Dynamic Friction, Measured Wet
Where the old test records the force needed to break a stationary contact loose, ANSI A326.3 draws a moving SBR rubber sensor across a floor wetted with sodium lauryl sulfate solution, simulating a heel already in motion on a wet surface. The 2017 edition set the criterion most spec readers know: level interior floors expected to be walked on when wet should show a wet DCOF of 0.42 or greater. The February 2022 revision (A326.3-2021) added product-use classifications with higher minimums for harder exposures, including 0.55 where oils and greases are present. Those classifications map directly onto food-facility floor conditions.
SCOF vs DCOF Conversion — None Exists
Static and dynamic friction are different physical quantities. The test conditions differ too: D-2047 runs dry on the James Machine, while A326.3 runs wet on a tribometer. A floor can post a high dry SCOF and still fall short of the wet DCOF criterion once water, cleaning solution, or process soil sits on it. No arithmetic relates the two values, and any chart claiming to convert SCOF 0.6 into a DCOF equivalent is invented. The correct move with a legacy number is re-evaluation, not translation.
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Reading a Legacy Slip-Resistance Requirement
“SCOF 0.6” in the Spec — What It Asks For Today
Treat a legacy SCOF requirement as a statement of intent rather than a number to match. The intent was a floor that resists slips; the current instrument for that intent is wet DCOF under ANSI A326.3, selected for the floor’s actual exposure class. A dry corridor reads against the 0.42 interior-wet criterion. A kitchen line or processing floor that sees oil, grease, or animal fat reads against the 2021 revision’s oils-and-greases classification at a 0.55 minimum. Substituting current criteria at spec review is standard practice — chasing the original dry static value would certify the floor against the wrong condition.
Thresholds Are Acceptance Criteria, Not Product Specs
A wet DCOF of 0.42 is the standard’s pass line, not a property a finished floor carries unconditionally. The installed value moves with texture selection, topcoat, broadcast media, and ongoing maintenance, and A326.3 itself cautions that a passing number does not by itself rule out slips in service. The defensible pattern is specifying that the finish meet the A326.3 criterion for the declared use classification, then confirming on a sample panel or with on-site tribometer testing after installation. A number measured on a lab panel is a starting point, not a closeout document.
Where the B101 Standards Fit in the Lineage
Between the dry static era and A326.3 sits the NFSI B101 series, which brought wet testing into the field — B101.1 for wet SCOF and B101.3 for wet DCOF. Consolidation came through tile. The Tile Council of North America carried the 0.42 wet DCOF criterion into ANSI A137.1, and the 2012 International Building Code referenced it. From there A326.3 became the test method current flooring documentation cites. A spec citing B101.3 reads forward the same way a D-2047 spec does, except that B101.3 was already a wet dynamic method, so its intent translates more directly.
Hitting a Wet DCOF Target in Urethane Cement
Texture Is the Lever — Broadcast and Profiled Systems
Urethane cement reaches wet-traction targets through surface texture set during installation. Broadcast systems such as Sherwin-Williams Poly-Crete SLB and Poly-Crete MDB seed aggregate into the wet body coat, and Sika Ucrete UD 200 SR is the slip-resistant grade of the heavy-duty trowel system. Smooth self-leveling finishes sit at the low-texture end of the range and suit dry or lightly wet zones. Because texture is selected per zone, one facility can run an aggressive profile at the fryer line and a cleanable, lower-profile finish in dry packaging — each matched to its A326.3 use classification.
How Craftsman Handles the Old-Spec Conversation
When a bid document carries a legacy SCOF line, our estimators flag it at spec review and propose current ANSI A326.3 language scoped to each zone’s wet exposure. Texture mockups precede the pour, and sample panels give the owner a physical reference for the traction-versus-cleanability tradeoff before material ships. In-house W-2 crews mobilize nationwide. Pre-bid walkthroughs are available within regional drive radius; remote spec review standard for multi-region rollouts.
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Frequently Asked Questions
SCOF is static coefficient of friction: the force needed to start motion, historically measured dry on the James Machine under ASTM D-2047. DCOF is dynamic coefficient of friction: resistance to motion already underway, measured wet under ANSI A326.3 with an SBR sensor and SLS solution. Wet dynamic testing reflects how slips actually occur, which is why current flooring documentation reports DCOF.
No. The two methods measure different physical quantities under different surface conditions on different instruments, and no arithmetic relationship connects their values. A floor with a dry SCOF of 0.6 can still fall short of the 0.42 wet DCOF criterion once water or cleaning solution is on it. Re-evaluate the floor against ANSI A326.3 for its real exposure instead of converting the old number.
The requirement reflects an older test era. ASTM D-2047 measures dry static friction on polish-coated surfaces, so a 0.6 SCOF line on an industrial floor was borrowing a criterion from outside its scope even when it was written. Current practice replaces it at spec review with wet DCOF language per ANSI A326.3, scoped to the floor’s declared use classification.
ANSI A326.3 sets 0.42 wet DCOF as the minimum for level interior floors expected to be walked on when wet. The 2022 revision adds higher minimums by exposure: 0.50 for wet-plus interior areas and 0.55 where oils and greases are present, which covers most kitchen and processing lines. The right target depends on the declared use classification, not a single universal number.
For hard-surface flooring, ANSI A326.3 is the current reference: a wet dynamic test developed with the Tile Council of North America, with its 0.42 criterion carried into ANSI A137.1 and the 2012 International Building Code. The NFSI B101 series introduced wet testing between the two eras. D-2047 remains an active ASTM method, but its scope is polish-coated surfaces tested dry.
Texture selection is where the standards transition lands on a real project. A floor specified to a wet DCOF target gets a broadcast or profiled finish, such as Sherwin-Williams Poly-Crete SLB or Sika Ucrete UD 200 SR, while dry zones can run smooth self-leveling finishes that clean faster. Texture is chosen zone by zone against the A326.3 use classification and confirmed on sample panels before installation.
Yes. A bid document carrying an old SCOF number gets re-scoped during estimating, so contract language reads in current ANSI A326.3 terms before material is ordered, and the closeout package documents the use classification each zone was finished to. In-house W-2 crews mobilize nationwide, installing industrial flooring since 1999.
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