Final answer:
For clients with 80 to 100 percent gray hair, semi-permanent haircolor is the most flattering option as it offers a more natural look and makes root regrowth less noticeable. Semi-permanent dye results in subtle color variations that blend gray and white hair well. Yet, as graying increases, adding permanent highlights can help in achieving better coverage.
Step-by-step explanation:
For clients who are 80 to 100 percent gray, a haircolor within the semi-permanent range is generally most flattering. Semi-permanent color is beneficial because it washes out over a period of typically four to six weeks, which makes root regrowth less noticeable. As gray and white hair may not absorb dye the same way as pigmented hair, using a semi-permanent color can result in a more natural look with subtle variations in color. This can be less harsh than a permanent dye, which makes it more flattering for those with a high percentage of gray hair. It's important to note that as the amount of gray or white hair increases, clients may need to consider permanent highlights in addition to semi-permanent base color to achieve the desired coverage and blending.