A low porosity strand will always float on top/ near the top of the water. If you try to force the strand under the water, you'll find it will float back up to the top every single time. This is because the strong structure of the strand prevents the hair from taking in much water at all, causing it to float! In comparison, high porosity hair is more porous which allows the strand to take in more water. As it takes in more water, the strand sinks further to the bottom of the bowl. You might find if you leave a high porosity hair in water for a very long time, the hair starts to float. This is because the strand has soaked up all the water it needed. Therefore, be sure to check your results for the porosity test within the first few minutes of putting the hair in the bowl as that will give you the most accurate reading of what your porosity is!