Shine Vinegar should be applied after having carried out your entire hair washing routine (shampoo and hair care). It should be used before rinsing hair once last time. It helps to eliminate any residue that dull the hair fiber and that could have been left on hair during washing. Rinsing one last time with water will help to wash out the vinegar (since the hair has been treated with the vinegar just before, residue won't be able to rest on hair).