How is a hair porosity test typically performed?

A hair porosity test is typically performed by soaking a strand of hair in water. This method assesses how well the hair absorbs moisture, which is a key indicator of its porosity level. When hair is soaked, those with high porosity will absorb water quickly and may even become saturated, while low porosity hair will resist absorption and may float on the surface for a longer time. This test helps in understanding the hair's health and how it will react to various treatments and products.

Brushing the hair or backcombing it do not provide valuable information regarding porosity, as these techniques primarily affect the hair's surface rather than its ability to absorb moisture. Additionally, using a specific chemical solution is not a standard method for testing porosity and could alter the hair's condition rather than assess its natural state. The soaking method is a straightforward and effective way to gauge porosity, making it the most relevant choice.