Final answer:
The process of evening out porosity and depositing a base color is designed to create a uniform color base in the hair, ensuring even color absorption and coverage across the head, which is particularly important when covering gray hair or moving from semi-permanent to permanent color.
Step-by-step explanation:
The process of evening out porosity and depositing a base color serves to create a uniform color base for the hair. It allows the hair to achieve a more consistent shade across all strands by initially mitigating variations in hair porosity, which can affect how the hair absorbs and retains dye. Moreover, this base helps to cover grays and provides a foundation for the color that follows, whether it be permanent or semi-permanent, promoting a more natural and even hair color after the application.
Permanent hair coloring alters the hair's structure and typically involves a three-step oxidation process that removes the natural color and replaces it with a synthetic one. A semi-permanent color, on the other hand, washes out after several weeks and tends to have less uniformity in coloration due to varying porosity and natural hair color, which can be remedied by using it as a base before applying permanent color.