What the float test can tell you
Take a strand of hair, fill a glass with water and allow that strand of hair to be placed in that glass of water. Hair that floats to the top of the water for a while before sinking toward the bottom is likely to be low porosity.
Hair that floats somewhere near the middle of the glass likely has medium porosity.
Hair that sinks to the bottom of the glass fairly quickly is typically more porous. That means it has high porosity.