Narrow Elastic Fabrics, Generally Accepted Laboratory Practices and Fabric Tolerances

NTA-NEMA – 9/84
REV.3/89

Following are laboratory practices and fabric tolerances used by manufacturers of narrow elastic fabrics. Narrow elastic fabrics include woven, knit and braided fabrics which do not exceed 12 inches in width and contain elastomeric fibers (spandex or rubber).

These methods and tolerances are not to be construed as industry standards or association policies and are reported here only to promote uniform understanding of prevailing practices in the industry. Individual companies will prepare, test, market and distribute their products using methods which are consistent with company practices.

Recommended Laboratory Conditions for Testing

It is recommended that narrow elastic fabrics be tested in a laboratory environment where the temperature is 70 degrees Fahrenheit, plus or minus two degrees (68°-72°). The relative humidity in the laboratory environment should be 65%, plus or minus 2% (63%-67%).

Stretch Tolerances

The following tolerance is applicable to hand stretch, machine stretch /*/ and drop weight systems:

The tolerance of narrow elastic fabrics is ± 10% of the specified stretch with a minimum of ± 10 points.

Examples: Fabric has 70% stretch specification; tolerance is 60%-80%.

Examples: Fabric has 120% stretch specification; tolerance is 108%-132%.

Certain fabric constructions may require additional tolerances.

Width Measurement and Tolerance

The minimum width should be measured from edge to edge of the body of the narrow elastic fabric.

Tolerances for the following fabric widths are given below:

1. From 0 inches to 31/32 inchs in width, the tolerance is ± 1/32 inch;
2. From 1 inch to 1-31/32 inches in width, the tolerance is ± 1/16 inch;
3. From 2 inches to 3-31/32 inches in width, the tolerance is ± 1/8 inch;
4. From 4 inches to 9-31/32 inches in width, the tolerance is ± 1/4 inch;
5. 10 inches and greater in width, the tolerance is ± 1/2 inch.

Tension Tolerance

For fabrics of 0% to 100% stretch, the tolerance is ± 15% to be read at the 30% elongation level on the third outgoing (loading) cycle.

For fabrics of 100% and higher stretch, the tolerance is ± 15% read at the 50% elongation level on the third outgoing (loading) cycle. The test weight is determined by the amount needed to extend the fabric to its ultimate elongation.

Weight Measurement and Tolerance

In the absence of explicit agreement to the contrary by the contracting parties, it is generally accepted that the weight quoted for narrow elastic fabrics is based upon ounces per hundred linear yards of conditioned and relaxed fabric.

The generally accepted tolerance is ± 10% of the measured weight.

Yield, Pick and Stitch Tolerance

The generally accepted tolerance of yields, picks and stitches is set at ± 10%.

/*/ Machine Testing – Constant-rate-of-load (CRL): Scott IP4 type – Constant-rate-of-extension (CRE): Zwick type