Color uptake is fastest in which hair type?

• A. Fine, porous hair
• B. Coarse, non-porous hair
• C. Medium, non-porous hair
• D. Thick, porous hair

Answer: (A)

Color uptake hinges on how easily color molecules can penetrate the hair shaft, which depends on porosity and the hair’s diameter. Porous hair has a more open cuticle and a cortex that’s easier for chemicals to reach, so color can enter faster. Among porous hair types, fine hair processes the quickest because its smaller diameter creates a shorter diffusion path into the cortex and a higher surface-area-to-volume ratio, exposing more cuticle surface per strand to the color. Coarse or thick hair has a thicker shaft and a tougher cuticle, so even with porosity, the color molecules travel a longer path, slowing uptake. Non-porous hair resists penetration overall, making uptake slower regardless of thickness. So the fastest color uptake occurs in fine, porous hair.