How can I check the stretch recovery of a sample before approving it?

Main answer

You can compare the stretch recovery of a sample against an approved reference with a simple gauge test: mark a fixed length, stretch it to a set amount, hold it, release it and measure again after resting. This shows relative growth, not a standard result, so use it to compare samples and send a standard laboratory test for production decisions.

What you need

A ruler or tape, a marker or pins, a clean flat surface and a timer. Take the sample, such as a waistband, cuff or panel, and mark two points a fixed distance apart, for example 10 centimetres, on the relaxed fabric. Do the same on an approved reference sample so both can be compared under the same conditions.

The test steps

Stretch the fabric along the direction of wear to a set point, such as to a measured length that matches how it is worn. Hold for a fixed time, for example one minute, then release it without pulling. Let it rest, then measure the marked distance again at fixed intervals, such as after a minute and after a few hours.

Reading the result

If the distance has not returned to the original, the difference is permanent growth, shown as a percentage of the original length. Compare the sample with the reference, in the same direction and with the same stretch. A sample that stays longer than the reference will probably sag in wear. Repeat on several pieces.

What this does not show

A home check cannot replace laboratory methods. ASTM D2594, for example, covers tension testing of low-power stretch knit fabrics. Home tests also miss the effect of washing and of repeated stretching. Use them to screen samples, then ask for lab results on the bulk fabric and a wash test. See underwear fabrics and performance fabrics.