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D2209-00 – Standard Test Method Technical Guide
ASTM D2209-00 (Reapproved 2021) defines the standard test method for determining the tensile strength of leather. The method measures the load required to rupture a test specimen with a width of 1/2 inch (12.7 mm). Tensile strength is calculated by dividing this load by the original unstretched cross-sectional area. This test method is excellent for development, control, specification acceptance, and service evaluation of leather, though it specifically excludes wet blue and requires leather that is smooth enough for accurate thickness measurement.
📐 Scope and Specimen Preparation
The standard applies to all types of leather that are smooth and firm enough to permit accurate thickness measurements, explicitly excluding wet blue. Specimens are conditioned according to Practice D1610. Thickness is measured in the center of the narrow area of the specimen using Test Method D1813. The standard specifies that values in inch-pound units are the standard; SI values provided in parentheses are mathematical conversions for information only. The specimen orientation relative to the backbone and its location on the hide significantly influence the results.
⚙️ Test Procedure and Speed Requirements
The test requires a power-driven machine with a load indicator that records the maximum load at rupture. The specimen is clamped in grips with knurled or roughened faces, measuring at least 1 by 1 1/2 inches (25.4 by 38 mm), mounted with the longer dimension perpendicular to the applied load. The power-activated grip moves at a uniform speed of 10 ± 2 inches per minute (254 ± 50 mm/min). The width and thickness are measured in the center of the narrow area before clamping. The force required to rupture the specimen is recorded, and the tensile strength is calculated. The percent elongation at rupture is also measured.
📊 Key Measured Properties and Calculations
Tensile strength is reported in psi or kPa by dividing the rupture force by the original cross-sectional area (width multiplied by thickness). The percent elongation at rupture is measured in accordance with Test Method D2211. The following tables summarize the critical parameters and calculations defined in the standard.
| 🟦 Critical Parameter | 📏 Specification from ASTM D2209 |
|---|---|
| Specimen Width | 1/2 in. (12.7 mm) |
| Testing Speed (Jaw Separation) | 10 ± 2 in./min (254 ± 50 mm/min) |
| Minimum Grip Face Dimensions | 1 x 1 1/2 in. (25.4 x 38 mm) |
| Grip Orientation | Longer dimension perpendicular to the applied load |
| Measured Outputs | Load at Rupture, Tensile Strength (psi/kPa), Elongation (%) |
| 📐 Calculation | 🎯 Formula or Method |
|---|---|
| Tensile Strength (T) | T = Force at Rupture / Original Cross-sectional Area |
| Cross-sectional Area | Width × Thickness (measured at center of narrow section) |
| Elongation at Rupture | Measured per Test Method D2211 |
| Unit System Priority | Inch-pound units are standard; SI units are mathematical conversions |
⚠️ Material Exclusion: ASTM D2209 explicitly does not apply to wet blue. The test specimen must be from leather that is smooth and firm enough to permit accurate thickness measurements. Practitioners must verify the material state before testing.
💡 Significance of Results: Low tensile strength values reliably indicate improperly lubricated or partially degraded leather. The specimen’s orientation relative to the backbone and its location on the hide significantly influence the results. This test method is excellent for development, quality control, specification acceptance, and service evaluation when conditions match the specified method.
❓ Frequently Asked Questions
🔍 What is the standard specimen width for this test?
The standard specifies a specimen width of 1/2 inch (12.7 mm). The thickness and width are measured in the center of the narrow area of the specimen.
💡 What are the required machine specifications for speed and grips?
The testing machine must provide a uniform jaw separation speed of 10 ± 2 inches per minute (254 ± 50 mm/min). The grips must have faces at least 1 by 1 1/2 inches, be knurled to prevent slipping, and be mounted with the longer dimension perpendicular to the load direction.
🔍 Which ASTM standards are referenced for conditioning and thickness?
The standard refers to Practice D1610 for conditioning leather and leather products for testing. Thickness measurement of the test specimens is performed in accordance with Test Method D1813. General terminology follows Terminology D1517.
📌 Is this test method applicable to all types of leather?
This test method may be used for all types of leather that are smooth and firm enough to permit accurate thickness measurements. However, it specifically does not apply to wet blue.