Cold water closes the pores and prevents dirt from entering and accumulating on the scalp. Not only does it close the pores, it also closes the hair cuticle, sealing in moisture from the conditioner that you applied to your hair. Whereas hot water can remove the moisture from your hair, cold water retains the moisture and the natural sebum that’s so beneficial. Don’t forget, more moisture means less frizz. Cold water retains your hair’s moisture, and adds luster to your locks.