I've done the "floating" test several times over the last couple of years. I always suspected that the test was flawed, because I couldn't believe that after all I've done to my hair, it's "low" porosity. (Although, this may be the reason why I got away with abusing my hair so much). I started researching other "symptoms" as they came up, i.e. products "foaming" like shampoo on wet hair, hair taking 10 hours to dry, glycerin causing stiffness, tangles and dryness (during low dew points), positive response to "steam". They all turned out to be characteristic of low porosity
Here's a few links that helped me:
Applying Products to Low Porosity Hair
Porosity and Curly Hair
LOW POROSITY (I copied & pasted this info. from Search Results
Hair with low porosity has a tightly bound cuticle layer with overlapping scales that lay flat. This type of hair is usually considered healthy, and is often very shiny, especially when it's dark in color. Low porosity hair repels moisture when you try to wet it and is hard to process since it resists penetration of chemicals.
Low porosity hair is also prone to build-up from protein-rich deep conditioning products, which can leave it feeling stiff and straw-like. Stick to protein-free, daily conditioners with humectants such as glycerin or honey. Use moderate heat with protein-free deep conditioning treatments to help open up the tightly bound cuticle.
Low porosity hair requires moisturizers rich in emollients such as shea butter, jojoba oil, coconut oil and mineral oil. It also benefits from humectant products, which attract and hold moisture to your hair. Choose lighter, liquid-based products such as hair milks that won't sit on your hair and leave it oily or greasy.
In hair with low porosity, the cuticle layer is more tightly closed. Hair is slower to absorb water and longer to release it, so low porosity hair holds moisture quite well. But with fewer surface openings for product to be absorbed into, build up on the hair’s surface can happen quickly. Too much conditioning and excessive stylers may coat the hair and rob it of its vitality and bounciness. Some styling products may even sit on your hair or create a white cast. And because there’s little margin for absorption on low porosity hair’s smooth surface, excessive or pure protein treatments may cause the crispy, straw-like feel of protein overload.