The science behind shampoo bars: Why solid shampoos work better
There is a widespread misconception about solid shampoos: that they are an environmentally friendly alternative that compromises on results. That people choose them for the planet, not for their hair.
That is not true. And science explains why. Want to see immediately which shampoo bar suits your hair? Read our guide to the best shampoo bar.
Surfactants, what actually cleans
All shampoos clean with the help of surfactants, molecules that bind to both oil and water and lift dirt and sebum from the scalp. The difference between a conventional shampoo and a shampoo bar lies in which surfactants are used.
Conventional shampoos often use sulfates such as Sodium Lauryl Sulfate or Sodium Laureth Sulfate. They are effective cleansing agents, but they are also harsh—harsh enough to disrupt the scalp's natural pH balance and strip the outermost lipid layer from the hair shaft.
FOAM's shampoo bars are formulated with Sodium Cocoyl Isethionate, a mild surfactant naturally derived from coconut. It cleans effectively without triggering the scalp to overproduce sebum or drying out the lengths. Read more about how to build a hair care routine with a shampoo bar that makes full use of this.
Concentration, more of what matters
A conventional shampoo bottle consists largely of water, up to 80 percent in many products. The water is not active; it is a carrier for the active ingredients and a way to make the product liquid.
A shampoo bar is pure concentrate. Without water as a filler, each gram of the bar contains a higher proportion of active ingredients, natural oils, plant extracts and surfactants that actually do something for your hair.
The Editor's Note: A 60-gram shampoo bar is equivalent to approximately two to three bottles of liquid shampoo. It is not only better for the environment, it is also better value and gives you better hair per pound spent.
Natural oils and butters, moisture that stays put
Without water as a carrier, the shampoo bar can be formulated with a higher proportion of natural oils and butters. Coconut oil penetrates the hair shaft's outermost layer and delivers moisture from within. Grapeseed oil provides shine without weighing the hair down. Blueberry seed oil repairs oxidative stress in damaged hair.
These ingredients do not merely leave a superficial film of shine; they work deep within the hair's protein structure. This is especially important for dry hair and coloured hair that needs extra protection.
Without preservatives
Liquid products require preservatives to remain stable. Solid products do not, because without water there is no environment for bacteria and mould to grow in. This means a cleaner ingredient list and a product that lasts longer without additives.
The shampoo bar is not a compromise. It is a better choice—for your hair, your scalp and sustainability.