The GB/T 3921-2008 standard applies to the colour fastness test of Spinning & weaving products under soaping conditions. This standard evaluates the performance of Spinning & weaving products in soaping resistance by simulating the cleaning process in actual use. The test covers different types of Spinning & weaving products, including dyed or printed fabrics, as well as different cleaning conditions and methods. Through this standard, the colour fastness grade of Spinning & weaving products after multiple washes can be determined, helping manufacturers and consumers understand their color Stability in actual use. This information is important for guiding the design, selection and use of Spinning & Weaving products, helping to ensure that the mass and performance of the products meet the expected requirements.