Regarding the issue of gray fabric dyeing, please help explain what this sentence means.

There are many causes of water stains. Your description is not clear enough, so I can only give you a general explanation:

After dyeing, it needs to be washed with water to remove floating color. It is not easy for the color to fade in the hands of consumers. However, if the water hardness is too high during the washing process, the calcium and magnesium ions in the water will combine with the detergent anions to form precipitates, which will contaminate the cloth and cause white marks, which is a kind of water stain.

If the fastness of the dyeing itself is not good, color flow will be formed during washing. If this color flow is not washed thoroughly, it will also form water stains

If the cloth is processed in a rope shape Yes, scratches caused by friction when the cloth is circulated in the equipment also look similar to water stains.