When searching for the best shampoo bar, it is worth knowing that the term encompasses two very different products: saponified shampoo bars with a high pH, and pH-balanced shampoo bars with mild surfactants. What determines the result on your hair is precisely this difference, not whether the product is solid or liquid.
Interest in solid shampoo products has grown rapidly. But so has the confusion. In everyday speech, shampoo bar is used as a collective term for anything solid that washes the hair, even though the chemical differences are significant. Understanding what you are actually looking at in the store can save you from costly mistakes and disappointment.
Two types of solid shampoo – very different results
A saponified shampoo bar is made by reacting oils with lye, a classic soapmaking process. The result is a high pH of around 9–10. This is far from the hair’s natural pH environment of 4.5–5.5 and causes the cuticle layer to swell with every wash. The hair feels coarse, dry and frizzy, especially at first.
A shampoo bar is something different from a saponified soap, but quality varies depending on the manufacturer. A good shampoo bar is pH-balanced and formulated with mild, sulfate-free surfactants. A poorer one may have a high pH or contain sulfates such as SLS, just like conventional liquid shampoo. Read more about the difference in our guide to shampoo bars vs shampoo bars.
What to look for in the store
- Ingredient list: Soap salts such as Sodium Cocoate or Sodium Palmate = a saponified product with a high pH. Also avoid sulfates such as SLS and SLES, which occur in both liquid and solid shampoos.
- pH information: Choose a shampoo bar that states that it is pH-balanced. If the manufacturer does not mention pH, that is a warning sign.
- Adjustment period: If the manufacturer warns that your hair may feel heavy during the first few weeks, this is due to a high pH, not because your hair is “getting used to it”.
Want to compare it with liquid shampoo? Read our article on shampoo bars vs liquid shampoo.
Tip from foam.nu: Have you tried a solid shampoo product and been disappointed? You probably tried a saponified shampoo bar, or a shampoo bar with sulfates or a high pH. Not all solid shampoos are created equal.
Ready to find the right one? Read our complete guide to shampoo bars and see which option best suits your hair type.