What technique is used in "foil highlighting"?

Foil highlighting is a technique that involves applying dye to specific sections of hair and wrapping those sections in foil. This method serves several purposes: it helps to isolate the hair that is being highlighted from the rest of the hair, preventing the color from bleeding into other sections, and it also allows for precise control over the coloring process. The foil reflects heat back to the hair, which can enhance the lightening or coloring process, leading to more vibrant and defined highlights.

This technique is particularly popular because it can create a dimensional look with bright highlights that stand out against the base color of the hair. By isolating each section, stylists can achieve different levels of lightness or color intensity, allowing for a customized result.

In contrast, the other options describe different coloring methods that do not involve the use of foil and do not provide the same level of precision and vibrancy in highlights. For example, coloring the entire head without separation refers to a more uniform application that does not create highlights or dimension, while coloring by hand without tools lacks the control offered by foiling. Using a comb to distribute color evenly might apply in certain techniques, but it does not encapsulate the focused approach that foil highlighting entails.