The hair and scalp have a ph. Having the correct ph balance seals the hair cuticles making it smooth and shiny. The ph scale goes from 1-14 measuring the acidity or alkalinity, with 7 being neutral. The perfect ph for hair is 5.5-6.5, the higher the ph the wider the hair cuticles are open.
An apple cider vinegar rinse will balance the ph of the hair closing the cuticle, and will restore ph on the scalp. It is also good to get a shampoo that says ph balanced. A ph balanced shampoo that I like to use is, Avalon Organics Awapuhi Mango Moisturizing Shampoo.
I am so addicted to doing ACV rinses, I do them at least every 2 weeks, and my hair comes out so shiny and with less frizz.
For your ACV mix you will need 1/4 cup of apple cider vinegar added to 2 cups of water. This rinse will be your last step after washing your hair. I prefer to leave my ACV rinse in and not rinse it out, the smell disappears as it dries, but you can rinse it out.