I'm familiar with a number of different colors of thread locker and the strength/usage guidelines. I've never heard of "hardening" vs. "non-hardening" until today though.
The front sprocket installation guide for my Katana specifically requires "non-hardening thread locker" while totally leaving out any mention of strength. If I'd not seen that line, I would have just used blue... Now though I'm wondering as I have no idea if blue is hardening or not. Spec sheets and Google have been no help either.