A hair coloring technique called "root tapping" blends new gray growth into colored hair using semi-permanent color applied only at the root, avoiding the stark line that forms between retouched hair and regrowth, according to Harper's Bazaar.
Katie Collins, a color specialist at Haug London Haus, said the technique, which she calls the "lip gloss method," can cover up to 70% of gray hair while adding shine and dimension rather than full coverage. She said the semi-permanent formula used includes Aquaxyl, an ingredient meant to help stabilize moisture levels and protect against breakage, making it an option for hair that has become thinner or more brittle.