Shine Vinegar should be applied after having carried out your entire hair washing routine (shampoo and treatments/conditioners). It should be used before the last rinse and helps to eliminate any residues that dull the hair fiber and that could have been left on the hair during washing. The last rinse with water will help to wash out the vinegar (as the hair has been treated with the vinegar just before, the residue won't be able to sit on the hair).