Why do temporary color pigment molecules not penetrate the hair?

The correct answer indicates that temporary color pigment molecules do not penetrate the hair because they are too large. Temporary color products are designed to coat the outer layer of the hair shaft rather than penetrate it. This lack of penetration is important as it allows for the color to be easily washed out, making temporary colors a flexible option for clients who want to change their hair color without a long-term commitment.

In contrast, smaller pigment molecules found in semi-permanent and permanent color can penetrate the hair cuticle and enter the cortex, resulting in more lasting color changes. Temporary colors rely on larger pigments that adhere to the surface, which is why they do not affect the internal structure of the hair.

This understanding highlights why temporary colors are often used for quick applications for special occasions, allowing clients to try out different shades without the commitment of more permanent options.