Q: What is the best water to wash your hair with: cold, warm or as hot as possible?
A: For the average person, who simply wants to shampoo his or her moderately-soiled hair, warm water is the way to go. Warm water allows the shampoo to most effectively remove the dirt and oils in the hair, and
helps the conditioner smooth the hair and rinse away cleanly.
However, there are cases where hot or cold water can have an added benefit. When the hair is heavily soiled with build-up of products or waxy substances, using hot water provides
a better clean from the shampoo used. The heat and moisture help to expand the cuticle layer somewhat and can help conditioners to penetrate more deeply when applied to hair warmed by hot water. In these cases, the
conditioner should be rinsed using tepid or cooler water.
Cold water rinses after shampooing and conditioning help to tighten up the cuticle layer and can be beneficial for those who have problems with oily scalp and hair. The cold water
helps to tighten pores and slow down oil production in the skin for a period of time following the rinsing.