What are Hair building fibers? Hair fibers are made of organic and sometimes synthetic ingredients or both. The fact that they are organic or not, keratin or not, have no significant value. The Hair fibers are designed to help hair looking fuller and better but do not improve your own hair health, hair loss or any other problem they truly provide a cosmetic purpose. However hair fibers do not harm you in any way or decrease your hair growth. Good hair fibers will give you great natural-looking coverage for longer time without irritation and they should stay on your head not on your face and shoulders.