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D2322-14 – Standard Test Method Technical Guide
🧪 Overview and Purpose of Test Method D2322
ASTM D2322 – 14 (Reapproved 2023) provides a standardized procedure for evaluating the durability and resistance of shoe upper leather when exposed to artificial perspiration. This test method quantifies deterioration by measuring the resistance to grain cracking in accordance with Test Method D2210 (the Mullen Test) and by assessing any loss in specimen area. While changes in flexibility are known to occur during this process, these effects have not been formally established as definitive criteria for this specific test method.
⚠️ Important Scope Limitation: This test method is specifically designed for finished shoe upper leather and explicitly does not apply to wet blue (chrome-tanned leather in its wet state). Prior to testing, all specimens must be conditioned according to Practice D1610.
🧬 Artificial Perspiration Reagent and Specimen Geometry
The core of the test relies on a specific formulation of artificial perspiration, adjusted to an alkaline pH of 8.5. The solution closely mimics the chemical composition of human sweat that is specifically aggressive towards leather breakdown. The pH is adjusted as required using either lactic acid or ammonium carbonate.
| 🧪 Reagent Component | ⚖️ Quantity (per litre) |
|---|---|
| Sodium Chloride | 9.0 g |
| Urea | 1.67 g |
| Sodium Lactate (60% solution) | 86.0 g |
| Disodium Phosphate (Na₂HPO₄·12H₂O) | 0.165 g |
| Distilled Water | to make 1 litre |
For testing, two square specimens are required. Each specimen must measure exactly 3 in. ± 0.0625 in. (76 mm ± 1.5 mm) per side. One specimen acts as the untreated control. The other, designated for exposure to the perspiration solution, is marked for identification by punching an approximate 0.06 in. (1.5 mm) hole in two of its corners. Sampling of leather must adhere to Practice D2813.
| 📐 Specimen | 🔖 Identification Method | 🎯 Test Function |
|---|---|---|
| Control Specimen | No holes (plain) | Baseline measurement for comparison |
| Exposure Specimen | Two punched holes (0.06 in.) | Subjected to artificial perspiration reagent |
⚙️ Apparatus, Procedure, and Key Measured Properties
The exposure apparatus consists of a circulating-air oven capable of maintaining the required temperature within ±4 °F (2 °C), a ½-gallon (1.9 L) wide-mouth bottle with an airtight closure, and a glass tray 1.5 in. (38 mm) deep. After the prescribed exposure period, the deterioration of the leather is evaluated by comparing the control and exposed specimens using the Mullen Tester to measure grain crack resistance (per D2210) and by calculating the percentage of area loss.
✅ Core Deterioration Criteria: The primary indicators of performance or wear resistance are:
- Grain Cracking Resistance: Loss of burst strength measured by the Mullen Test (D2210).
- Area Loss: Physical shrinkage or dissolution of the leather specimen.
❓ Frequently Asked Questions
🔍 How is the test specimen exposed to perspiration prepared?
The specimen designated for exposure is a 3 in. by 3 in. square cut from the sample. It is identified by punching an approximate 0.06 in. (1.5 mm) hole in two of its corners to distinguish it from the control specimen after testing.
💡 What is the pH of the artificial perspiration used in this test?
The solution is specifically adjusted to a pH of 8.5 using lactic acid or ammonium carbonate. This alkaline formulation is designed to simulate specific conditions that are conducive to leather breakdown.
⚡ Can this method be used to test any type of leather?
No. Section 1.1 of the standard explicitly states that “This test method does not apply to wet blue.” The standard is specifically intended for evaluating finished shoe upper leather.
📌 What are the main properties used to judge deterioration?
Deterioration is judged primarily by two factors: the reduction in resistance to grain cracking as measured by Test Method D2210 (the Mullen Test), and the measurement of area loss compared to the untreated control specimen.