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D1516-05 – Standard Test Method Technical Guide
ASTM D1516-05 (Reapproved 2021) establishes a standardized test method for measuring the width of leather test specimens and regularly shaped units. This protocol is fundamental for evaluating dimensional stability and is specifically referenced for determining changes in area after physical or chemical tests. Adherence to this standard ensures consistency and accuracy in leather quality assessment across laboratories.
📐 Scope and Significance of the Standard
The scope of D1516 covers the determination of width for physical test specimens and regularly shaped pieces of all types of finished leather. It is explicitly designed to facilitate measurements before and after destructive testing, such as the change in area of square pieces when measuring resistance to synthetic perspiration solution. A key scope limitation is that this test method does not apply to wet blue leather. Values are reported in inch-pound units, with SI unit conversions provided for reference only.
The significance of this test method lies in its ability to provide a reproducible basis for measuring dimensional change. By standardizing the measurement technique, it supports the validity of subsequent calculations required by other test methods.
⚙️ Testing Procedure and Apparatus
The procedure requires a steel scale graduated to 0.02 in. (0.5 mm) or a steel tape graduated to 1/16 in. or millimeters. Specimens must be conditioned for a minimum of 48 hours in a standard atmosphere of 73.4 ± 1.8 °F (23 ± 1 °C) and 50 ± 4 % relative humidity, as specified in Practice D1610. During testing, the specimen is placed on a flat surface and flattened without pulling or stretching. Measurements are taken at the designated locations specified by the particular test method for which the specimen was prepared.
| 🟦 Environmental & Apparatus Standards | 🎯 Specification / Value |
|---|---|
| 📏 Steel Scale Graduation | 0.02 in (0.5 mm) |
| 📏 Steel Tape Graduation | 1/16 in or millimeters |
| ⏳ Conditioning Duration | 48 hours |
| 🌡️ Standard Temperature | 73.4 ± 1.8 °F (23 ± 1 °C) |
| 💧 Standard Humidity | 50 ± 4 % RH |
📊 Reporting Results and Precision
Reports must document the width of test specimens as prescribed by the primary physical test method. For regularly shaped units or pieces, the average of all width measurements is reported to the same accuracy as the original observations. The standard defines precision based on data from a round robin involving 3 laboratories. A coefficient of variation of 1.8% can be expected between laboratories for headband leather subjected to a perspiration test, provided at least 15 units have been tested.
| 📐 Key Metric | ⚡ Reported Value |
|---|---|
| Measurement Resolution | Nearest 0.02 in (0.5 mm) |
| Minimum Units for Precision Claims | 15 units |
| Between-Lab Coefficient of Variation | 1.8 % (headband leather) |
📌 Key Conditioning Requirement: The specimen must be conditioned for 48 hours at 73.4 °F (23 °C) and 50% RH prior to measurement. This stabilization is critical for achieving the dimensional consistency required for accurate test results.
⚠️ Application Warning: This test method is not intended for wet blue leather. Applying the procedure to wet blue will produce invalid results, as the material has not undergone the finishing processes for which the dimensional stability tests are designed.
❓ Frequently Asked Questions
🔍 What types of leather are covered by this standard?
This standard applies to all types of finished leather and regularly shaped units. It explicitly does not apply to wet blue.
💡 How is the measurement taken to ensure accuracy?
The specimen must be placed on a flat surface and flattened without pulling or stretching. The width is measured to the nearest 0.02 in. (0.5 mm) at the designated location.
⚡ What is the reported precision between different laboratories?
Based on an interlaboratory study (round robin), a coefficient of variation of 1.8 % can be expected for width measurements of headband leather subjected to a perspiration test.
📌 What apparatus is required for this test method?
The required apparatus includes a steel scale graduated to 0.02 in. (0.5 mm) and a steel tape graduated to 1/16 in. or in millimetres for measuring larger pieces.