I currently have unbleachable hairline knots in my new system. I find this sometimes happens on hair systems with SFS front but thinskin or ilace base - not sure why, perhaps it's the hair used in the skins.

I've left the knots in bleach for about 50 minutes, and only a few of them got bleached. The rest stayed totally original colour. I've had this issue before with an ilace piece, and after 3 bleach attempts I gave up.

With SFS and #64 systems, I've never had this problem.

I'm currentl wearing my system with unbleached hairline knots, and it actually looks fine because it's quite a thick hairline... but I wouldn't mind getting some of the bleached, perhaps there is some way?