The dye in henna infuses skin, hair, and porous surfaces but does not permanently or chemically alter them. The 'strength' of the stain is affected by numerous factors including skin type, temperature, hormone levels, and stress. After the dried paste is removed from skin, the stain will darken over the next 48-72 hours. The dye stains the outermost layer of the skin and will initially appear as light/dark orange and darken to a red brown. Henna appears darkest on hands and feet because they have thicker skin than other parts of the body.