Oooh, you know, that might be something totally different that we're talking about here. That discoloration is something totally different than what I thought you were talking about. Where do you live? This may actually be a bleaching effect, which could be the result of bleach being used to clean your washing machine or of some minerals in your water, etc. Ultimately, I don't think it is the result of the fabric, but rather the way the fabric interacts with a foreign body in your water. I've had this type of bleaching effect occur on some of my clothes, mainly on olive colors. Do you wash your clothes in a machine at home, or in a commercial/community machine? By the way, is that on the inside of the color, so that you can't see it when the collar is folded down?