How does natural hair dyes work?
Permanent hair dyes or synthetic dyes, contain chemicals such as ammonia or its substitutes that enables the diffusion of the tint into the cortex of the hair fibre to break up the melanin (the natural dye molecule of the hair) and replaces it with a new colour. Bleaching and hair lightening works similarly to enable the diffusion of the melanin in the cortex. Natural Ingredients, such as henna are tannins similar to black tea and are acidic in nature and stain naturally. Some tannin such as Henna seems to work better at retaining a colour on hair compared to other tannins such as tea. Henna contains a dye molecule called Lawsone which is orange/red in colour. When henna is coated on the hair, lawsone is absorbed into the outer layers of the hair (keratin) and creates a colour shade that is a mixture of the natural colour of the hair (melanin) and orange/red (from lawsone). Grey hair for example, has no melanin and will result in orange/red hair if dyed using henna. The lawsone molecul
