Apply slowly to dry hair, distributing evenly from root to tip. Work No.0 into small sections by squeezing the liquid into the hair to be fully absorbed as you go. Lightly saturate from root to tip. Hair should be damp, not drenched. Let process for 10 minutes. Do not rinse. 
 
For the complete treatment, apply No.3 Hair Perfector over hair with No.0 applied to it, combing through as needed. Let process for a minimum of 10 minutes. Rinse, shampoo and condition.  For best results, use No.4 Shampoo and No.5 Conditioner.
 
No.0 bottle should last 3-6 applications, based on hair length and density.