1. Test items
Fiber composition: Determine the proportion of cotton in cotton cloth to prevent unscrupulous merchants from mixing other cheap fibers to pass off as good ones. Accurately identify by observing the fiber morphology under a microscope and chemical dissolution methods to ensure the purity of the ingredients.

Strength performance: includes tensile strength and tear strength. Tensile strength measures the bearing capacity of cotton cloth under longitudinal tension, and tear strength reflects its tear resistance, which is directly related to the wearing life of clothing. Work clothes and denim require high strength and high test values.

Color fastness: such as color fastness to washing and color fastness to friction. Color fastness to washing is related to whether the color fades after washing, and color fastness to friction involves the color stability of clothing during daily wear and friction. Severe fading not only affects the appearance, but may also stain other items.

Shrinkage rate: Due to the characteristics of cotton fibers, cotton cloth is easy to shrink. Detecting its warp and weft shrinkage rates can reserve sizes for clothing cutting and home textile production to avoid the finished product being ill-fitting after washing.

2. Testing methods
Physical performance testing: Strength testing uses a strength machine to stretch the fabric sample at a uniform speed until it breaks, and record the tensile force value. Shrinkage testing is to cut a fixed size fabric sample, wash it, and dry it to measure the size change and calculate it.

Chemical analysis method: Fiber composition testing, using the difference in fiber dissolution characteristics of different chemical reagents, observing the dissolution situation to determine the composition.

Color fastness testing: Simulating actual use, water washing color fastness sews the fabric sample with the standard adjacent fabric, and evaluates the discoloration and staining level after washing and drying according to regulations; friction color fastness uses a friction meter to simulate dry and wet friction, and compares the color card rating.

3. Testing standards
Domestic standards include GB/T 406-2018 "Cotton Natural Fabric", etc., which stipulate cotton fabric specifications, technical requirements, and test methods; international standards such as ISO 139-2005 "Textiles Standard Atmosphere for Humidification and Testing" standardize the testing environment temperature and humidity, and unified standards provide a basis for global cotton fabric trade quality judgment and encourage enterprises to produce in compliance.

4. Significance of testing
Ensure that consumers wear comfortable, safe and durable cotton clothing to avoid skin allergies and other problems. For enterprises, quality control can enhance brand reputation, reduce after-sales disputes, help the industry develop healthily, and promote fine control of cotton fabrics from raw materials to finished products, so that this traditional fabric continues to shine.