ISO, ASTM, and GB are three commonly used standards for evaluating fabric colorfastness. While these standards share some similarities, there are also important differences between them.

1. ISO Standards: The International Organization for Standardization (ISO) has developed a series of standards for evaluating colorfastness in textiles, including ISO 105-X12, which covers colorfastness to rubbing. ISO standards are widely recognized and used around the world, and they provide a common language and methodology for evaluating colorfastness. ISO standards typically include detailed specifications for test methods, sample preparation, and evaluation criteria.

2. ASTM Standards: The American Society for Testing and Materials (ASTM) has developed a series of standards for evaluating colorfastness, including ASTM D2054, which covers colorfastness to rubbing. ASTM standards are widely used in the United States and other countries, and they are designed to provide a comprehensive approach to evaluating colorfastness. ASTM standards typically include detailed procedures for sample preparation, test methods, and evaluation criteria.

3. GB Standards: The Chinese National Standards (GB) are a series of standards developed by the Standardization Administration of China (SAC) for the evaluation of textile materials, including colorfastness. GB/T 3920-2013 is the standard for evaluating colorfastness to rubbing. GB standards are widely used in China, and they provide a systematic approach to evaluating colorfastness. GB standards typically include detailed procedures for sample preparation, test methods, and evaluation criteria.

While these standards have some similarities in terms of their approach to evaluating colorfastness, there are also some important differences. For example, the ISO and ASTM standards tend to be more widely recognized and used globally, while the GB standards are primarily used in China. The specific test methods, sample preparation, and evaluation criteria may also differ between these standards, which can affect the results obtained from testing. Therefore, it is important to carefully select the appropriate standard and test method based on the specific requirements of the application and the geographic region where the product will be used.