Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D2098-21 – Standard Test Method Technical Guide
ASTM D2098-21 provides a standardized method for evaluating the dynamic water resistance of shoe upper leather using the Dow Corning Leather Tester. This test simulates the repeated flexing a shoe vamp undergoes in wet conditions, assessing how well the leather and its finish resist water penetration and absorption. The method applies to all finished shoe upper leathers but explicitly excludes wet blue and wet white materials.
📐 Apparatus and Specimen Configuration
The core of the apparatus is the Dow Corning Leather Tester, consisting of two vertical clamps mounted on stainless steel arms measuring 7.5 by 0.5 by 0.5 in. (190.5 mm by 12.7 mm by 12.7 mm). One clamp is fixed while the other is attached to a horizontal reciprocating shaft driven by a motorized eccentric. The flexing motion is precisely defined by the dimensional limits of the clamp stroke.
The water tank, made of stainless steel or another noncorrosive material, surrounds the clamps. The tank depth is critical: its top must be at least 2.5 in. (63.5 mm) above the bottom of the clamps, and its bottom must be at least 0.5 in. (12.7 mm) below the clamp bottom to ensure consistent full immersion during the dynamic cycle.
| 🟦 Component | 📏 Specification | 📐 Dimension |
|---|---|---|
| Minimum Distance Between Clamps | 1.50 ± 0.01 in. | 38.1 ± 0.25 mm |
| Maximum Distance Between Clamps | 2.50 ± 0.01 in. | 63.5 ± 0.25 mm |
| Clamp Arm Dimensions | 7.5 x 0.5 x 0.5 in. | 190.5 x 12.7 x 12.7 mm |
| Water Tank Depth (above clamp bottom) | Min. 2.5 in. | Min. 63.5 mm |
⚠️ Important Distinction: This test method (D2098) is not interchangeable with Test Method D2099 (Maeser Water Penetration Tester) for specification purposes. The flexing mechanism and failure detection systems differ significantly and may yield different performance rankings for the same material.
⚙️ Test Procedure and Failure Detection
The test specimen is mounted in the clamps and flexed at a rate of 60 cycles per minute. A unique feature of the Dow Corning Tester is its dual system for recording cycles and detecting failure. A mechanical reset counter tracks total cycles, while an electrical system simultaneously monitors the integrity of the leather. The electrical circuit is configured with a resistance threshold of 7500 ohms ± 500 ohms.
Water penetration is detected when the circuit closes. The sensing electrode is housed inside a pouch formed by the leather specimen and filled with stainless-steel balls. The common electrode is placed directly in the salt solution of the water tank. When water dynamically penetrates the flexing leather, the resistance drops to the threshold, completing the circuit and stopping the mechanical counter. This provides a direct measurement of the number of cycles to initial water penetration.
| ⚡ Parameter | 🎯 Requirement |
|---|---|
| Flexing Frequency | 60 cycles/min |
| Electrical Resistance Threshold | 7500 ± 500 ohms |
| Balance Sensitivity (Weight) | 0.01 g |
To determine water absorption, the specimen is weighed before the test and immediately after the completion of the flexing cycle. The difference in mass, measured using a balance sensitive to 0.01 g, represents the amount of water absorbed. This value is typically expressed as a percentage of the original specimen weight.
💡 Technical Note: The flex imparted to the leather in this test is designed to be a magnification of the flex given to the vamp of a shoe in actual wear. Strict conditioning of specimens per Practice D1610 is mandatory for achieving consistent and reproducible results.
📊 Key Measured Properties and Significance
The primary properties measured are the cycles to initial water penetration and the percentage of water absorption. The flexing action stresses the leather’s surface finish and internal structure simultaneously. A higher number of cycles to penetration indicates superior water-resistant finish and leather compactness. The water absorption value details the long-term resistance to waterlogging.
This standard is widely used in the footwear industry for quality control and material qualification. It provides a comparative basis for evaluating the performance of water-resistant treatments and formulations. Because the flex is a magnified simulation of actual wear, it serves as a reliable predictor of field performance for shoe upper leathers under dynamic wet conditions.
❓ Frequently Asked Questions
🔍 What specific types of leather are excluded from this test method?
This test method specifically applies to finished shoe upper leathers. It explicitly does not apply to wet blue or wet white leathers, which are in an intermediate stage of processing.
💡 How is the failure point (water penetration) detected in the Dow Corning Tester?
Failure is determined by a drop in electrical resistance to 7500 ohms (± 500 ohms). The sensing electrode inside the specimen and the common electrode in the salt water tank form an open circuit until water penetrates the leather, completing the electrical circuit and stopping the test.
⚡ What are the critical dimensional specifications for the test apparatus?
The machine must run at 60 cycles per minute. The clamps must cycle between a minimum distance of 1.50 ± 0.01 in. (38.1 ± 0.25 mm) and a maximum distance of 2.50 ± 0.01 in. (63.5 ± 0.25 mm). The clamps are constructed from precisely dimensioned stainless steel arms.
📌 Can results from the Dow Corning Tester (D2098) be compared to results from the Maeser Tester (D2099)?
No. The standard explicitly cautions that this test method cannot be used interchangeably with Test Method D2099 for specification purposes. The mechanical flexing action and the water penetration detection systems are fundamentally different, which can lead to different performance ratings for the same leather.