Q: I want to go sulfate-free and try shampoo bars, but I've seen mixed reviews. Will they work for my hair?
A: To answer this question, let's examine the ingredients list of two popular shampoo bars...
Shampoo Bar 1: purified water, glycerin, sodium stearate and sodium oleate, sorbitol, stearic acid, lauric acid, African black soap, cocoa butter, cetyl alcohol, coconut oil, lavender, tea tree and citrus essential oils
Shampoo Bar 2: purified water, saponified olive, coconut and safflower oils, jojoba oil, shikakai & amla herbs, apple cider vinegar and panthenol
The two shampoo bars are made with slightly different recipes, but the cleansing ingredient in both of them is soap. Scientifically speaking, the "sodium stearate and sodium oleate" in Shampoo Bar 1 are the same as the "saponified olive, coconut and safflower oils" in Shampoo Bar 2. The first bar lists the scientific name for soap, while the other used more laymen terms. Soap is made by mixing water, fat from an oil or butter, and lye (sodium hydroxide). In the "sodium oleate" listed in Shampoo Bar 1, the "sodium" comes from sodium hydroxide and the "oleate" means the fat used was from olive oil.
There are two major problems with using soap to wash your hair:
Problem #1: It is impossible to make a pH balanced soap bar. As we know, sodium hydroxide has a high pH and the resulting soap usually has a pH around 10. Skin and hair are made of keratin proteins and all types of protein are sensitive to pH. Our skin and hair can better maintain their natural strength when they are kept at acidic pH values between 4.5 and 6.5 during cleansing. An expert soap maker can make a soap bar as low as pH 8, but attempting to lower the pH below 8 will make the soap look more like a creamy liquid (not a solid bar anymore). Some hair types aren't affected by high pH, but coils and curls are more sensitive because of their naturally raised cuticles. Raised cuticles cause dry, tangle prone hair. A shampoo with a pH between 4.5 and 6.5 will cleanse your hair without causing more tangles.
Problem #2: Soap causes soap scum in hard water. When you use a shampoo bar in tap water that contains a lot of calcium, the calcium ions will attach to the saponified olive oil/sodium oleate and form scum that settles on your hair (and leaves stains in the tub). The calcium residue will make your hair more prone to tangles and knots. Hard tap water is common in Southern California, the Mid West, and Texas. If you have hard water, your hair will feel and look better if you avoid soap. Most shampoos contain natural chelating ingredients like Phytic Acid or Disodium EDTA that counteract the effects of hard water.
My recommendation is that you choose a shampoo made with more gentle cleansing ingredients like "Sodium Cocoyl Isethionate" , "Sodium Methyl Taurate" and "Disodium Cocoamphodipropionate". Those are sulfate-free detergents that are used in pH balanced shampoos. If you choose to wash your hair with a shampoo bar or any other soap, you can rinse off any calcium residue that may be on your hair at the end of your shower using 1 cup Apple Cider Vinegar mixed with 1 cup purified water.