Static Coefficient of Friction · BOT-3000E
SCOF testing when a spec
calls for it.
We measure static coefficient of friction with the BOT-3000E when a manufacturer, standard or legacy report requires it. We’ll also tell you honestly why it shouldn’t be the number you make safety decisions on.
What is static coefficient of friction?
SCOF measures the friction needed to start a stationary object moving — the resistance at the instant before motion begins. It’s the oldest form of floor-friction measurement, and it’s still requested by some tile manufacturers, flooring warranties, and standards such as ANSI/NFSI B101.1. Our BOT-3000E can measure SCOF as well as dynamic COF, so if your specification calls for a static number, we can produce one to a recognized method.
Why we don’t recommend SCOF for slip prevention
Real slips happen while a foot is moving. At heel strike, the heel is traveling at roughly walking speed when it contacts the floor. Static friction, measured from a standstill, has no reliable statistical correlation with these real, dynamic, wet slips. A floor can post a reassuring SCOF while people are actually falling on it. That’s exactly why the standards community withdrew the old static test (ASTM C1028) and moved to dynamic measurement.
When SCOF testing still makes sense
- A tile or coating manufacturer’s warranty or spec requires an ANSI/NFSI B101.1 or ASTM D2047 value
- You’re matching the methodology of a prior report for a like-for-like comparison
- A contract or purchasing standard specifies a static number
- You need the full picture and want static and dynamic values side by side
What we recommend instead
For decisions about whether a floor is actually safe to walk on wet, we recommend Pendulum Test Value (PTV) under ASTM E303-22 or dynamic coefficient of friction (DCOF) under ANSI A326.3 — the methods that measure friction in motion, the way people actually slip. When you book SCOF, we’re glad to run a dynamic test alongside it so you leave with a number you can act on. See SCOF vs DCOF explained.
Common questions
Can the BOT-3000E measure both SCOF and DCOF?
Yes. The BOT-3000E is a digital tribometer capable of both static and dynamic measurement. We can provide either or both.
If SCOF is unreliable, why offer it at all?
Because specifications, warranties and legacy reports sometimes require it. We provide it accurately, and we’re upfront about its limits so you don’t make safety decisions on the wrong metric.
What number should I actually use for slip risk?
PTV (ASTM E303-22) or wet DCOF (ANSI A326.3). The pendulum (PTV) is the reference for real-world wet slip risk; DCOF (A326.3) documents the U.S. compliance framework. For high-stakes wet work we prefer pendulum plus DCOF rather than treating them as equal predictors.
Need SCOF? We’ll do it right, and we’ll be straight with you about the number.
The research behind (and the limits of) SCOF
Static coefficient of friction is well standardized, but the research is clear that a standstill measurement poorly predicts a moving slip. Selected sources:
- ASTM D2047, Static Coefficient of Friction of Polish-Coated Flooring Surfaces as Measured by the James Machine — a dry, laboratory method for polish-coated floors.
- Chang, W.-R., Grönqvist, R., Leclercq, S., et al. (2001). The role of friction in the measurement of slipperiness, Parts 1–2. Ergonomics, 44(13) — why static friction correlates poorly with real, dynamic slips.
- Powers, C.M., et al. (2007). Gait-based assessment of walkway tribometer readings. Journal of Forensic Sciences, 52(2).
- This is why we report SCOF only when a manufacturer or legacy spec requires it, and never as the basis for a wet slip-risk conclusion.
Studies and standards are cited for reference. Consult the current published edition of any standard before making a compliance decision.