Shampoo bar is a collective term for solid shampoo products, but it encompasses two very different product types: saponified shampoo bars with a high pH and pH-balanced shampoo bars with mild surfactants. The difference is crucial to how your hair feels after each wash.
Interest in solid shampoo products is growing, and with it, confusion around the terminology has increased. In everyday speech, shampoo bar is used as a collective term for anything solid that washes the hair, but behind the simple format lies entirely different chemistry. This guide clarifies what you are actually looking at when making your choice.
What is the difference between a shampoo bar and a solid shampoo bar?
A saponified shampoo bar is made by saponifying oils with lye and has a high pH of around 9–10. This is far above the hair’s natural pH range of 4.5–5.5 and causes the cuticle layer to swell with every wash. A solid shampoo bar is something else: a solid formula with surfactants, whose quality varies depending on the manufacturer. A good solid shampoo bar is pH-balanced and cleanses without disturbing the cuticle layer’s natural closure. We cover all the differences in detail in our article about shampoo bar vs solid shampoo bar.
Shampoo bar vs liquid shampoo: which is best?
A high-quality solid shampoo product is more concentrated than liquid shampoo and requires no water in the formula, making it longer-lasting and easier to transport. But just as with liquid shampoo, ingredients and pH vary enormously between brands. The choice is not about the format but about what is actually in the product. You can find a complete comparison in the guide to shampoo bar vs liquid shampoo.
How do you find the best shampoo bar?
The most important thing is to choose a pH-balanced solid shampoo bar with mild surfactants and without soap salts such as Sodium Cocoate or Sodium Palmate. If you are unsure what to look for, we go through it step by step in the guide to the best shampoo bar. If you also want to understand why sulfate-free shampoo matters, or how to use the product correctly, you will find the answers in our guide to using a solid shampoo bar.
FOAM’s solid shampoo bar is pH-balanced, cleanses with a gentle, sulfate-free surfactant from coconut, and is suitable for all hair types without an adjustment period. We recommend trying our mini pack first to find your favorite.
Shampoo bars for your hair type: an overview
All hair types are different, and your shampoo choice should be adapted accordingly. Here are our guides by hair type:
- Shampoo bar for curly hair: pH and curl definition are connected.
- Shampoo bar for fine hair: gentle cleansing without weighing it down.
- Shampoo bar for a sensitive scalp: pH and mild surfactants are crucial.
If you also want to explore the solid shampoo bar perspective in greater depth, we recommend our complete guide to solid shampoo bars.