Hi! I'm a newbie here, and I have a question! I knit a pair of socks recently on #1 Addi Pro needles and used cotton sock-weight yarn. I noticed a ridge of grayish discoloration along the one sock which hasn't come out with regular washing.
My daughter is knitting on #000 needles and 100 % cotton crochet thread, and I'm noticing a similar thing happening with her project.
Does anyone know what this is, and how to prevent/remove it?