Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D2810-24 – Standard Test Method Technical Guide
📐 Scope and Key Definitions for D2810-24
This standard test method, designated D2810-24, provides a reproducible procedure for determining the pH of all types of finished leather. It explicitly does not apply to wet blue or wet white. The test measures the pH of a distilled water extract of the leather, serving as a critical quantitative indicator of its acidity or alkalinity.
In this standard, pH is defined as the negative logarithm of the hydrogen ion activity. A solution of pH 7 is considered neutral at 24°C. Lower values indicate increasing acidity, while higher values indicate increasing alkalinity. The standard also introduces the pH difference figure (delta pH), which is the difference between the pH of a solution and its ten-fold dilution.
⚠️ Impact on Material Performance: Excessive acidity or alkalinity may have a deleterious effect on the aging characteristics of leather. This test method is therefore suitable for development, control, and service evaluation to ensure product quality and longevity. All values in the test are expressed in SI units.
⚙️ Apparatus, Reagents, and Interference Protocol
The test requires precise instrumentation. An electronic pH meter with an accuracy of at least 0.01 pH unit and a reproducibility of 0.05 pH unit must be utilized. An analytical balance sensitive to 0.01 g or greater is also required. All reagents must be reagent grade, conforming to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available.
Handling Interferences: Leathers containing excessive fats, greases, or those treated for water repellency may resist wetting, directly affecting extractability. When a specimen is difficult or impossible to wet, a specific vacuum procedure must be employed. The specimen is placed in a stoppered flask with the required amount of water. An intermittent vacuum is applied (15 s to 60 s on, then 15 s to 60 s off) until the specimen is completely wetted out before proceeding with the standard extraction.
💡 Procedure Tip: The intermittent vacuum technique is critical for accurate results on water-resistant leathers. Continue the vacuum cycles until the specimen is completely wetted out before proceeding with the standard extraction procedure outlined in Section 10 of the method.
📊 Key Measured Properties and Equipment Specifications
The tables below summarize the critical technical specifications and definitions required by D2810-24 to ensure accurate and reproducible pH measurement of leather.
| 🟦 Apparatus / Parameter | 📏 Required Specification |
|---|---|
| pH Meter Accuracy | ±0.01 pH unit |
| pH Meter Reproducibility | ±0.05 pH unit |
| Analytical Balance | Sensitive to 0.01 g |
| Vacuum Cycle Duration | 15 s to 60 s (intermittent) |
| Standard Measurement Units | SI Units |
| 🎯 Property / Application | ⚡ Definition / Constraint |
|---|---|
| Neutral pH (at 24°C) | 7.0 |
| Delta pH Calculation | pH (extract) – pH (ten-fold dilution) |
| Excluded Materials | Wet blue, wet white |
| Sampling Standard | ASTM D2813 |
❓ Frequently Asked Questions
🔍 What is the exact scope of ASTM D2810-24?
This test method covers the determination of the pH of all types of leather. It is a measure of acidity or alkalinity from a distilled water extract. It explicitly does not apply to wet blue or wet white leather.
💡 Why is a vacuum sometimes required during specimen preparation?
If the leather contains excessive fats, greases, or has a water-repellent finish, it may be difficult to wet. An intermittent vacuum (15 s to 60 s) is applied to the stoppered flask to force the extraction water into the specimen, ensuring proper contact and accurate extraction.
⚡ What are the minimum performance requirements for the pH meter?
The electronic pH meter must have an accuracy of at least 0.01 pH unit and a reproducibility of 0.05 pH unit. This ensures the measurements are sensitive enough to detect meaningful changes in leather acidity or alkalinity for development and quality control.
📌 How is the ‘pH difference’ (delta pH) defined and used?
The pH difference figure (delta pH) is the difference between the pH of the leather extract and the pH of its ten-fold dilution. It provides insight into the buffering capacity of the leather, which can be related to the type and amount of acid or alkali present in the sample.