When looking for the best shampoo bar, it’s worth knowing that the term covers two very different products: saponified shampoo bars with a high pH, and pH-balanced shampoo bars made with mild surfactants. What determines the results on your hair is precisely that difference, not whether the product is solid or liquid.
Interest in solid shampoo products has grown rapidly. But so has the confusion. In everyday usage, “shampoo bar” is used as an umbrella term for anything solid that washes your hair, even though the chemistry can be very different. Understanding what you’re 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 traditional soap-making process. The result is a high pH of around 9-10. That is far from the hair’s natural pH range of 4.5-5.5, and causes the cuticle to swell with every wash. Hair feels rough, dry, and frizzy, especially at first.
A shampoo bar is different from a saponified soap, but quality varies by manufacturer. A good shampoo bar is pH-balanced and formulated with mild, sulfate-free surfactants. A lower-quality 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 are found in both liquid and solid shampoos.
- pH information: Choose a shampoo bar that states it is pH-balanced. If the manufacturer doesn’t mention pH, that’s a warning sign.
- Transition period: If the manufacturer warns that your hair may feel heavy for 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 about 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.