Like most I cut up old tshirts for shop use - cleaning, applying abrasive paste, buffing, etc. I grabbed an old faded red cotton tshirt recently that was many years old and had been washed countless times. Soft and seemed OK to use. I used it to apply abrasive paste and when I grabbed a white cloth to do final cleanup I got a good bit of red stain on my cloth. Not fibers but color. Fortunately it was a dark piece so didn't impact the wood color and cleaned off OK but surprised that it would still impart some color. Guess the abrasive action worked it out of the cloth. Lesson learned, stick with white cloth.