When my dreads were past ... I duno 6 months? I used a little loose undyed felt (same kind used for crafts) on 2 of my dreads. They were small and not really locking up. I just kinda weaved it in there like you would a loose hair. It stayed. Cant see it anymore. Prolly cause my dreads eat things. They haven't gotten hard or uncomfortable in anyway. But ya, I wouldn't go over board with it.
7, I didn't use a felting needle for this experiment, but I did use one for the blue felt dread in the front of my dreads. Its really strong! I didn't find my hairs breaking though lol.