Why even the young dye

By Ethan Croft

Humans have tried to liven up drab hair with dye almost since recorded history began. The natural pigments of old – any substance that added colour – could turn grey hair blonde and make brown hair black. Henna, the pre-eminent natural dye for centuries, was easily extracted from trees in South Asia and north Africa. Until the 19th century it was the only safe way to rejuvenate your locks. Its use continues in large parts of South Asia today.

A synthetic solution was not found until 1883 when Ernst Erdmann, a German professor, discovered that instead of layering plant material on hair, a cocktail of chemicals could penetrate deep into each strand to change its colour. He patented his “new and useful improvements in Hair-Dye” in 1906.

Erdmann’s process, which persists to this day, comes in three straightforward phases. First, the hair is soaked in ammonia, opening up the protective layers of protein. Next, a mixture of colourless chemicals is applied (the choice of chemicals, and the quantity of each of them, determines the final colour). The colouring process is completed by an essential ingredient, hydrogen peroxide, which attacks the melanin that gives our hair its natural colour (as well as our skin and eyes). This last part of the process activates other chemicals present to produce a new pigment.

The fashion for stripped-out colour is the reason why, despite its cumbersome scientific name, hydrogen peroxide has entered the common language: some people pass over the middle phase for a starker look, applying only ammonia and peroxide to sap the melanin of its colour, leaving a snowy “bleach blonde” or “peroxide blonde” look. It takes 30 minutes to an hour for the necessary chemical reactions to run their course. The change is permanent – until your hair grows and your roots reveal your natural shade once again.

Despite the general mess and inconvenience of chemical dyeing, it caught on in the early 20th century and has remained popular. New home-colouring kits in 1950s America provided discretion and an affordable price tag. Today, some 60% of women in Europe say they dye their hair. In America the figure is over 70%. Despite recent warnings from scientists and politicians about potential side-effects of some chemical dyes (the European Union has to date banned 181 hair-colouring ingredients) the demand for dye persists. Hashtags such as #SaveYourRoots and #RootingForYourHairdresser circulated widely on social media when hairdressers were shut during lockdown, along with advice on how to dye at home.

Dyeing your hair has gone from a scientific marvel to become part of everyday life. Hair colour used to be an identifying feature on passports, as common as name and date of birth, but by the 1970s the governments of America and Britain had quietly dropped the category from such documents. Enter a hair salon today and you’ll find that the chemical augmentation of your locks is referred to not as dyeing, but as “colour correction”. Artificial is the new natural.■

image: getty