Final answer:
Semi-permanent hair color deposits color without mixing with peroxide and gradually washes out, whereas permanent hair coloring involves oxidation dyes and chemicals like 1,4-diaminobenzene to create a lasting change.
Step-by-step explanation:
The hair color being referred to in this question is semi-permanent hair color, which does not require mixing with peroxide and simply deposits color onto the hair. Unlike permanent hair color that uses oxidation dyes involving an oxidant and chemicals like 1,4-diaminobenzene, semi-permanent dyes coat the hair surface and wash out over time, usually in four to six weeks. This type of color application is less damaging to the hair and provides a more natural look because it does not permanently alter hair pigment or structure.
During the coloring process, the final result may vary based on the original hair color and its porosity. Semi-permanent color is generally unable to lighten hair or completely cover gray or white strands. For hair that has become significantly gray or white, it may become necessary to combine semi-permanent dyes with permanent coloring techniques to achieve the desired coverage.
In contrast, permanent hair coloring requires a combination of a diamine compound, a coupler, and an oxidant to create large dye molecules that are locked inside the hair, leading to a permanent color change. This process typically takes place under basic conditions, and the color does not wash out but requires growth or cutting to be removed.