GENTLE HAIR COLOUR

Frequent colouring can damage hair and has been linked to health risks from potentially cancer-causing dye components. Now, researchers from Northwestern University have developed a process to dye hair with synthetic melanin under milder conditions than traditional hair dyes. Melanin is a group of natural pigments that give hair and skin their colour. With ageing, melanin disappears from hair fibres, leading to colour loss and greying. Most permanent hair dyes use ammonia, hydrogen peroxide and other ingredients to penetrate the cuticle of the hair and deposit colouring. Along with being damaging to hair, these substances could cause allergic reactions or other health problems.

Recently, scientists have explored using synthetic melanin to colour human hair, but the process required relatively high concentrations of potentially toxic heavy metals. The new research out of Northwestern used small amounts of ammonium hydroxide and heat instead of the heavy metals to deposit the synthetic melanin on hair, creating conditions similar or milder than those used for commercially available hair dyes. The colouring is also deposited on the hair shaft, rather than penetrating the cuticle, making it less likely to cause damage, more gentle on the hair shaft and lasting at least 18 washes.