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D2347-00 – Standard Test Method Technical Guide
📐 Specimen Geometry and Measurement Parameters
This test method covers measurement of the surface area of leather test specimens, specifically the grain surface or the surface most closely adjacent to it. Specimens may be circular or rectangular, cut using a die of appropriate size with uniform dimensions in the 50 to 80 mm range. For rigid leathers like sole leathers, a knife may be used to obtain straight edges. The specimen area typically ranges from 1500 to 10 000 mm². The apparatus includes a die, mallet or clicking machine, rule or steel tape graduated to 1.0 mm, and a caliper recommended for sole leathers.
| 🟦 Parameter | 📏 Specification |
|---|---|
| Specimen Shape | Circular or rectangular |
| Die Dimension Range | 50 to 80 mm |
| Area Range | 1500 to 10 000 mm² |
| Measurement Precision | Nearest 1 mm |
⚙️ Test Procedure and Conditioning Requirements
Specimens must be conditioned in accordance with Practice D1610 for 48 hours in an atmosphere maintained at 73.4 ± 1.8 °F (23 ± 1 °C) and 50 ± 4% relative humidity. The procedure involves placing the specimen grain side up on a flat surface without stretching. For flexible leathers, use a rule or steel tape graduated to 1.0 mm; for sole leathers, a caliper is recommended. Three measurements are made along the width and three along the length to the nearest 1.0 mm. For circular specimens, measure the diameter four times at approximately 45° intervals using a rule or steel tape across the widest girth, and average the results to obtain the diameter.
| 🎯 Conditioning Parameter | ⚡ Requirement |
|---|---|
| Duration | 48 hours |
| Temperature | 73.4 ± 1.8 °F (23 ± 1 °C) |
| Relative Humidity | 50 ± 4% |
⚠️ This test method does not apply to wet blue leather. Ensure specimens are not taken from areas with surface defects such as indentations, creases, or cuts as specified in Section 6.3.
📊 Key Measured Properties and Calculations
The area of a circular specimen is calculated as the average diameter squared multiplied by π/4, reported to the nearest 1 mm². For rectangular specimens, the area is the product of the average width and average length measured on the grain surface, reported to the nearest 1 mm². This test method is designed to measure area before and after tests that may affect surface area, such as apparent density of leather or resistance of leather to synthetic perspiration solution as referenced in Section 4.1.
💡 For accurate measurements, ensure the specimen is spread out without pulling or stretching. Use the appropriate measuring tool based on leather flexibility: rule or tape for flexible leathers, caliper for sole leathers.
❓ Frequently Asked Questions
🔍 Which surface should be measured?
The grain surface or the surface most closely adjacent to the grain surface should be measured, unless otherwise specified.
💡 Does this test method apply to wet blue?
No, this test method does not apply to wet blue leather.
⚡ What is the recommended conditioning period?
Specimens should be conditioned for 48 hours at 73.4 ± 1.8 °F (23 ± 1 °C) and 50 ± 4% relative humidity according to Practice D1610.
📌 How should defective areas be handled?
Do not die out or cut specimens from areas that show surface defects such as indentations, creases, or cuts.