How well does this dye cover grey hair and how long does the black shade stay intense?

This is a permanent cream dye formulated for clear grey coverage and a deep, even black (shade 1.0). The rice protein in the color cream forms a light film on the hair surface that helps reduce rapid loss of dye molecules, so the shade stays visually intense longer than many temporary or semi-permanent alternatives. Because it is permanent, new growth at the roots will be visible as your hair grows — typically every 4–6 weeks depending on growth speed — so plan touch-ups accordingly. For the most uniform result from roots to ends, apply the mixture methodically using the creamy texture to distribute it evenly through all lengths. The included fixing balm, applied after rinsing the color, adds keratin to smooth the cuticle and a vitamin complex that helps the finished shade look sleeker and the hair feel softer, which also supports color retention by keeping the hair surface in better condition.