Wash hair with a clarifying shampoo and let it air-dry without products
Place a clean strand of hair in a glass of water
If the strand floats, hair is likely low porosity
If the strand sinks slowly, hair is likely normal porosity
If the strand sinks quickly, hair is likely high porosity
Spray a small section of dry hair with water
If water beads on the surface, hair is likely low porosity
If water absorbs at a moderate rate, hair is likely normal porosity
If water absorbs very quickly, hair is likely high porosity
Run fingers up a strand from ends to roots
If the hair feels very smooth, hair is likely low porosity
If the hair feels slightly rough, hair is likely normal porosity
If the hair feels very rough or damaged, hair is likely high porosity
Check how long hair takes to dry after washing
If it dries slowly, hair is likely low porosity
If it dries at an average rate, hair is likely normal porosity
If it dries very quickly, hair is likely high porosity
Observe how well hair holds moisture and products
If products sit on top of hair, hair is likely low porosity
If products absorb evenly, hair is likely normal porosity
If hair loses moisture quickly, hair is likely high porosity