Myth: The Float Test Measures Porosity
A strand in a glass of water is not a measurement.
Last reviewed by the Hairavie editorial team on September 1, 2026.
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Why it doesn't work
- Product residue on the strand changes how it behaves in water
- Surface tension can hold a strand up regardless of its condition
- Strand thickness and length affect the result
- Water temperature and how the strand was dropped both matter
- One strand doesn't represent your whole head
What's more informative
How your hair behaves is a better signal than a glass of water: how quickly it wets in the shower, how long it takes to dry, and whether products absorb or sit on the surface.
Hairavie estimates porosity from behaviour and always shows a confidence level rather than asserting certainty.
How Hairavie knows this
Hairavie cites peer-reviewed research, scientific reviews, reference textbooks, dermatology organisations and government health resources. Beauty blogs are never used as scientific authority.
- Reference textbookRobbins, C. R. (2012). Chemical and Physical Behavior of Human Hair (5th ed.). Springer
- Scientific reviewGavazzoni Dias, M. F. R. (2015). Hair cosmetics: an overview. International Journal of Trichology
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