Porosity
puh-ROSS-ih-tee
The way a hair fiber allows water and other substances to move into and out of its structure.
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Hair porosity describes how readily water and other substances can enter and leave the hair fiber. The cuticle, the protective outer layer of the strand, plays an important role in controlling that movement. Cuticle condition can change with weathering, heat, chemical processing, and mechanical damage, so porosity is not necessarily a fixed characteristic for life and may vary along the same strand.
In consumer hair care, porosity is commonly described as low, medium, or high. These labels can be useful for describing how hair behaves, but they should be treated as practical shorthand rather than precise clinical classifications. Instead of relying solely on popular DIY tests, Coded Coil emphasizes observable behavior: how quickly clean hair wets, how products absorb, how rapidly moisture seems to leave, and whether damaged sections behave differently.