Color fastness, textile processing or use in the process is not easy to fade, poor color fastness, there will be fade, discoloration, or staining, etc., causing a lot of trouble. It can improve the color fastness of light measures. The rational use of dyes, in improving the light fastness, the choice of dye is the key.
Clothing is colorfast if its colors and dyes do not bleed or run from the clothing. If you aren't careful, you may find out that clothing is not colorfast when it's too late after you have a laundry disaster on your hands. If you wash a red non-colorfast towel with white socks, you may end up with pink socks. Sometimes clothes need to be washed a few times to make sure any remaining dye is washed out. This is especially true for bright colored linens (towels, sheets, and blankets) and for dark colored denim items. You should first test clothing for colorfastness before using any type of bleach, bleaching solution or strong cleaning product.
Even vinegar or baking soda, which are essentially mild, can damage clothing that isn't colorfast.
You can take a small swatch of the fabric in question, cover part of it with a solid material such as a piece of cardboard or similar and place the swatch in a sunny south or west-facing window for a fairly long time. Check it occasionally by removing the block and see how much the remainder of the swatch has faded compared to the covered section.
For wash fastness you can cut two swatches of fabric. Place your control swatch in a drawer. Wash the other swatch in hot water with detergent in your washer and then dry in the dryer as many times as you wish. Comparing it each time with your control swatch will show you how the colour bears up to washing.
The most effecient way is that we can check the color fastness of a fabric by running a test. The test methods that we usually use for Crocking/Rubbing are called "BS EN ISO 105 X12" and "AATCC 8". We need a Crockmeter to carry out this test and below is how it typically looks like.
