Final answer:
Henna applied to white or light grey hair typically results in an orange to copper color, due to the pure and vibrant nature of the dye on hair lacking melanin.
Step-by-step explanation:
When henna is applied to white or very light grey hair, the resulting color is typically an orange to copper hue. This is because henna is a plant-based dye that contains lawsone, a naturally occurring substance that binds to the keratin in the hair. Different factors, like the original color and porosity of the hair, can affect the final shade.
White or very light grey hair lacks the pigmentation that would typically blend with the henna to produce different shades, so the result is a much more vibrant and pure shade of the dye. Semi-permanent colors, like henna, wash out over time and are less harsh than a permanent dye.
However, because hair's ability to absorb color decreases with age and loss of pigment, some white hairs may not absorb the henna dye at all. Therefore, the results with henna on white hair can be bright, vivid, and uniform in color compared to the more subtle variations.