1. Test items

Fabric composition: Accurately measure the proportion of cotton, polyester fiber, spandex and other ingredients. This is not only related to cost accounting, but also affects the characteristics of denim. For example, high cotton content means good air permeability and strong moisture absorption, and spandex content can improve elasticity.

Color fastness: including water washing, friction resistance, and light fastness. Washing color fastness reflects the color fading after washing, friction color fastness considers the degree of color shedding during daily wear and friction, and light color fastness determines the durability of color under outdoor light. Denim with severe fading will affect the appearance and quality.

Strength performance: There are tensile strength and tearing strength tests. Tensile strength tests the limit of the tensile force that the fabric sample can withstand in the warp and weft directions, and tearing strength measures the difficulty of the fabric being torn, ensuring that the denim is not easily damaged during wearing and processing.

2. Test method

Component analysis: Chemical dissolution method is often used to separate and quantify the components by using the solubility characteristics of different fibers in specific chemical reagents. With the help of professional instruments, such as fiber fineness meters, parameters such as fiber diameter are accurately measured to assist in judgment.

Color fastness test: Washing color fastness is based on national standards, simulating home washing conditions, sewing the fabric sample with the standard adjacent fabric, and comparing the degree of fading after the prescribed washing procedure. The friction color fastness is tested with a friction fastness meter, rubbing the surface of the fabric sample with dry and wet friction cloth to observe the color contamination. Light color fastness is tested in an artificial climate aging box, simulating sunlight exposure, and judging color changes.

Strength test: Tensile strength is tested with a universal material testing machine, fixing both ends of the fabric sample, stretching at a uniform speed until it breaks, and recording the maximum tensile value. Tear strength is tested with the help of a tearing instrument, applying external force to the pre-cut portion of the fabric sample, and measuring the force required to tear it apart.

3. Testing standards

There are ISO standards internationally, and GB/T standards are followed domestically. For example, GB/T 2910 stipulates the fiber composition analysis method, and GB/T 3920 clarifies the test details of friction color fastness. These standards standardize the test from all aspects, including experimental environment, operation process, and result evaluation, to ensure the accuracy and comparability of the test.

4. Significance of testing

From the production end, testing helps enterprises control quality, optimize processes, and reduce defective rates; in the circulation link, it provides quality basis for trade and avoids quality disputes; for consumers, wearing denim products that meet standards is comfortable and safe, and they can enjoy denim fashion. In short, denim testing is a solid guarantee for the stable operation of all links in the industrial chain.