The only reliable way to check porosity is to order a test like Firefox said. The floating test is not reliable because it also depends on different factors like water temperature, strand weight and what type of products the strand is coated with. A decent way of figuring out your porosity is to see if your hair sucks up the moisture you put on it.
Density: low
Porosity: high and med
Width: fine and med

Current products:
Body shop rainforest radiance shampoo
Body shop rainforest volumising conditioner
Body shop rainforest coconut hair oil

DT: greek yoghurt and gelatine mix