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D2047-17 – Standard Test Method Technical Guide
📐 Scope and Significance of D2047-17
ASTM D2047-17 establishes a rigorous laboratory test method for measuring the static coefficient of friction (SCOF) of polish-coated flooring surfaces utilizing the James Machine. This standard is the definitive procedure for evaluating slip resistance on polished walkways and is explicitly identified as the only method appropriate for testing polishes for specification compliance with the floor polish static coefficient of friction criterion. The method establishes a specific compliance threshold that a surface must meet to be classified as a nonhazardous walkway for human locomotion.
The standard is strictly confined to dry testing conditions. Section 1.1 specifies that the method is not intended for use on wet surfaces or on surfaces where the texture, projections, or clearance of the sculptured pattern prevents the machine foot from making adequate, uniform contact with the test area.
⚙️ Materials, Apparatus, and Calibration Requirements
The accuracy and reproducibility of the James Machine method depend entirely on strict adherence to specific materials and calibration protocols. The substrate surfaces must be prepared in accordance with Practice D4103, and test polishes must be applied following the procedures in Test Methods D1436. The James Machine itself requires systematic calibration as defined in Practice D6205.
One of the most critical controlled variables is the material used for the test foot, which simulates a shoe sole. The standard mandates a leather material that meets a strict federal specification to ensure valid and correlatable test data.
| 🟦 Component | 📏 Specification | 📐 Standard Reference |
|---|---|---|
| Test Foot Leather | Vegetable tanned & chrome retanned cattlehide; Type 1 (Factory Shoe Making), Class 6 Strips | Federal Spec KK-L-165C |
| Apparatus Setup | Verification of horizontal & vertical force measurements | ASTM D6205 |
| Substrate Standards | Standardized cleaning, leveling, and conditioning of test panels | ASTM D4103 |
| Polish Application | Controlled film thickness and drying procedures | ASTM D1436 |
📊 Key Measured Properties and Compliance Criteria
The primary property measured is the Static Coefficient of Friction (SCOF), defined as the ratio of the horizontal (shear) component of force required to just overcome friction resistance to the vertical (normal) component of force applied to the test foot. This value serves as the benchmark for the standard’s safety compliance criterion.
| 🎯 Term | ⚡ Definition | 🔍 Source |
|---|---|---|
| Friction | Resistance to relative motion developed between two solid contacting bodies at and parallel to the sliding plane. | Section 3.1.1 |
| Static Coefficient of Friction | Ratio of the horizontal force that just overcomes friction to the vertical force applied. | Section 3.1.3 |
| Dynamic Coefficient of Friction | Ratio of the horizontal force required to maintain constant sliding velocity to the vertical force. | Section 3.1.4 |
| Safety Criterion | A specific SCOF value that constitutes a nonhazardous, slip-resistant polished walkway surface. | Section 1.1 |
⚠️ Critical Scope Restriction: This test method explicitly excludes wet surfaces and any surfaces where the texture, projections, or clearance of the pattern does not permit adequate contact between the James Machine foot and the test surface. Applying this standard outside of its intended scope will yield invalid results.
✅ Verification of Leather Material: The leather specified under Federal Specification KK-L-165C is not optional. The test foot material must be vegetable tanned and chrome retanned cattlehide (Type 1, Class 6). Using substitute materials invalidates the correlation to human locomotion safety and voids compliance with the standard.
❓ Frequently Asked Questions
🔍 What specific leather is required for the James Machine test foot?
The standard mandates Federal Specification KK-L-165C, Type 1–Factory (for Shoe Making), Class 6–Strips. This is a specific vegetable tanned and chrome retanned cattlehide material designed to simulate worn shoe soles.
💡 Can D2047-17 be used for testing wet or textured surfaces?
No. Section 1.1 specifically excludes wet surfaces and surfaces with deep texture or sculptured patterns. The James Machine requires a flat contact plane to produce a valid static coefficient of friction measurement.
⚡ What does the “compliance criterion” in the standard entail?
D2047-17 establishes a specific static coefficient of friction (SCOF) threshold. Any polish-coated flooring tested under this method must meet or exceed this value to be classified as a nonhazardous surface for human locomotion.
📌 Which supporting ASTM practices are critical for executing this test?
Key supporting standards include Practice D4103 for substrate preparation, Test Methods D1436 for applying the emulsion polish, and Practice D6205 for calibrating the James Machine to ensure accurate force readings.