What colour result can I expect, especially on grey or white hair? — Natural indigo henna 100% 3*20 grams - BIO VITAL

The powder contains indigo as the primary colouring agent, which on its own gives a blue-black tone. In traditional two-step or blended herbal dyeing, henna (lawsone) provides an orange-red base that indigo then shifts toward brown, dark brown, or black depending on the ratio and your starting shade. On pigmented hair, the effect is a cool, deep enrichment. On grey or white hair — which lacks the underlying melanin to blend with — the indigo can appear more vivid, sometimes showing a bluish or greenish cast initially that usually settles after 24–48 hours as the pigment oxidises in air. Because every head of hair has a different percentage of grey, porosity, and previous colour history, the exact shade cannot be predicted from a chart. The source material explicitly recommends a strand test on a hidden section before full application, especially if your hair is very light, heavily processed, or recently chemically coloured.