How do volumizing hair care products work?

TP asks…What makes our hair have the potential to be voluminous and what is the science behind volumizing hair care products?

The Beauty Brains respond:

There are four key factors that determine the volume of your hair.

Why does hair have volume?

1. The number of hairs per square inch of scalp
More hairs equals greater volume.

2. The thickness of each hair
The greater the diameter of each hair fiber, the more overall volume your hair will have.

3. The flexibility of the hair fibers (known as the bending modulus)
This is essentially a measurement of the stiffness of each hair fiber. Fibers that are stiffer will stand up more on their own contributing to greater volume. Fibers with a low bending modulus will tend to be floppy and limp.

4. The interaction between hair fibers
Friction between hair fibers can increase volume because the hair fibers will rub against each other more and sort of lock into the position. This is why the old trick of back combing or teasing your hair works so well to add volume. It lifts the cuticles and creates a rough surface so the hairs snag against each other to create a more voluminous network of fibers.

What is the science behind those formulas that ensure voluminous hair?

Unfortunately haircare products can do nothing to address the first factor. (Unless of course you’re using a drug like Minoxidil which can help grow more hair.)

Some products claim to “plump up” or even double the thickness of hair fibers but this is just marketing hype. The only ingredient we’ve seen capable of increasing hair diameter even slightly is a high amount of Pro-vitamin B5. Of course you can always use a damaging chemical treatment like hair color to swell the fiber but such processes also cause damage. This is why most women feel they get a volume boost from their dye job.

Haircare products can improve hair stiffness. Polymers can provide a temporary coating that give the hair more rigidity. This is how volumizing styling products like mousses work.

Dry shampoos do a good job of increasing interaction between hair fibers because they deposit powder. The tiny particles of starch and talc rub against each other increasing friction and therefore improving volume. Some styling products do this as well.

Does shampoo even matter since you condition after?

Volumizing shampoos help in two ways: They should remove residue form stylers and conditioners that can rob your hair of volume. They can also deposit small amounts of stiffening polmyers that help give the hair more body. They are more effective if you don’t over-condition your hair after shampooing.