What characteristic of hair is analyzed to determine its porosity?

The characteristic of hair that is analyzed to determine its porosity is cuticle health. Porosity refers to the hair's ability to absorb and retain moisture, which is largely influenced by the condition of the cuticle, the outermost layer of the hair shaft. A healthy cuticle lies flat and provides a protective barrier, allowing for moderate moisture retention. When the cuticle is damaged or raised, it can lead to high porosity, meaning the hair can absorb moisture quickly but also lose it just as easily, resulting in dryness and brittleness.

In contrast, thickness relates to the diameter of the hair strands, and while it may affect overall hair health and styling decisions, it does not directly indicate porosity. Length, while relevant to styling and care needs, similarly does not provide insights into porosity levels. Color can affect appearance and may correlate with certain treatments, but it is not a determining factor for porosity, as coloring processes can change the cuticle's condition, impacting porosity indirectly. Thus, analyzing cuticle health provides the most direct assessment of hair porosity.