Soap and Curly/Wavy Hair: A Guide

Sulfates get a bad reputation, but soap is likely far worse for your hair. Soap is a type of surfactant made from fatty acids and alkali, and are chemically quite different from most surfactants used in shampoos. It used to be rare that soap was used on hair, but the increasing interest in more eco-friendly products like shampoo bars has changed that.

Why is soap bad for curly/wavy hair?

Most shampoos are carefully pH balanced to not disrupt the scalp and hair. Soap not so much. Soaps tend to have an alkaline pH around 9-10, compared to 6-7 for shampoo (which is closer to the pH of skin/hair).

Then there is the soap scum. If you have hard water, soap will chemically will react with the minerals in the water and create something called “soap scum.” It’s about the worst type of buildup there is and you do not want that in your hair. To contrast, shampoos are formulated to work well in hard water.

Finally, soap as a surfactant is usually much much harsher than surfactants like sulfates.

Soap is more natural than shampoos, but natural is not always better.

Is there a curly/wavy friendly shampoo bar?

Luckily, more and more shampoo bars are made with shampoo ingredients rather than soap. From a cosmetics formulation standpoint these are called “syndets” (short for synthetic detergents). They can be made from mild surfactants.

Here are a few that we’ve found:

• HiBAR - Maintain Solid Shampoo Bar
• Aspen Kay Naturals - Solid Shampoo Bar
• Refig Lemongrass Solid Shampoo Bar
• Vida Soothe Solid Shampoo Bar for Curly Hair