ASTM D1424:2021

Lot Sample – Randomly select the number of rolls or pieces of fabric indicated in an applicable material specification

Laboratory Sample: For acceptance testing, take a sample that extends the width of the fabric and approximately 1 m (1 yd) along the machine direction from each roll or piece of the sample lot.

From each laboratory sample unit, take five specimens in the warp and weft directions.

When cutting swatches of woven fabric, take care to align the threads running in the short direction parallel to the die in such a way that when the slit is cut, the subsequent tear is between these threads and not through them.

Cut specimens representing a broad distribution across the width and length, and preferably along the diagonal of the laboratory specimen, and no closer to the edge than one-tenth of its width.

Select the force range of the test instrument so that tearing occurs between 20 and 80% or 20 and 60% of the full scale range, as appropriate.

The maximum gauge pressure must not be more than 620 kPa (90 psi) and the minimum gauge pressure must not be less than 410 kPa (60 psi).

• To condition the specimens bringing them to an approximate moisture equilibrium in the standard atmosphere for conditioning textiles as indicated in Practice D1776
• Test Conditioning of Wet Samples:
  When desizing treatments are specified prior to wet testing, use desizing treatments that do not affect the normal physical property of the fabric as indicated in Test Method D629.

• Test the conditioned cylinders in the standard atmosphere. Sphere for testing textiles, which is 21 ± 1°C (70 ± 2°F) and 65 ± 2% relative humidity
• Place the pendulum in the starting position and the force register mechanism in its zero force position.

For slit (slot cut) specimens

• Place the long sides of the sample in the center of the clamps
• Close the clamps, securing the sample with approximately the same tension on both clamps.

The specimen shall be free with its top directed towards the pendulum to ensure a shearing action.

• Using the built-in blade, cut a 20 mm (0.787 in.) slit (slit) in the swatch extending from the bottom edge, leaving a 43.0 fabric remnant.±15 mm (1.69 ± 0.005 in.) remaining to tear.

For die-cut or hand-cut samples:

• If a non-slit die is used, manually cut a 20 mm (0.787 in.) long slit (slot) in the center of one edge of the longitudinal direction of the sample.
• Place the parallel, non-slit sides of the specimen into the clamps with the bottom edge placed carefully against the stops, the top edge parallel to the top of the clamp, and the slot located centrally between the clamps.
• Close the clamps, securing the sample with approximately the same tension on both clamps.

For testing wet samples:

• Remove a sample from the water and immediately mount it to the test machine in the normal setting. Perform the test within 2 minutes of removing the cylinder from the water.
• Press the pendulum stopper down to its limit and hold until the tear is complete and the pendulum has completed its forward swing.
• It catches the pendulum just after the threshold of its back swing and returns to its initial locked position.

Remove the tear specimen and continue until five tears have been recorded for each test direction and test condition.

Calculate the tear strength as the average tear force for each test direction and test condition for the laboratory sample unit and for the lot, to the nearest 1% of full scale range in cN, (gf), or lbf. .

• Report that the Elmendorf Tear Strength was determined as directed in Test Method D1424.
• Report the following information for each laboratory sample unit and for the lot as applicable to a material specification or contract order.
• Elmendorf Tear Strength for each test direction and test condition, as requested.
• Test condition (with or without wetting).
• Number of trials rejected due to transverse tear.
• When calculated, the standard deviation or the coefficient of variation.
• For data processed by computer, identify the program (software) used.
• Make, model, and capacity of the testing machine.
• Type of clamps used, manual or pneumatic (including pressure).