What type of hair color has the largest pigment molecule?

The choice of demi-permanent hair color is related to its pigment structure and how it interacts with the hair. Demi-permanent hair colors contain larger pigment molecules than temporary and semi-permanent options. These larger molecules allow demi-permanent colors to penetrate the hair shaft more effectively than temporary colors, which typically coat the hair rather than enter it.

Demi-permanent colors are formulated with a low concentration of peroxide, which helps to enhance the color but does not lighten the hair as much as permanent color would. This method allows for a more lasting change than temporary colors, which usually wash out after one or two shampoos due to their smaller pigment molecules that lack the ability to penetrate deeply into the hair.

In addition, permanent colors contain even smaller pigment molecules that can penetrate the hair shaft entirely and bond with the hair structure, offering the most enduring color change, while semi-permanent colors sit in between, offering a more moderate longevity compared to demi-permanent but generally utilizing smaller pigments. Thus, the choice of demi-permanent hair color stands out for its unique blend of larger molecules that remain effective in coloring while still being less permanent than the standard permanent hair dye.