Employed especially when more than one color is to be applied, this method ensures that only the desired hair strands are colored, and the rest spared.
The modern trend is to use several colors to produce streaks or gradations, but not all work on top of a single base color. Hair color was traditionally applied to the hair as one overall color. Hair dyeing is now a multibillion-dollar industry that involves the use of both plant-derived and synthetic dyes. In 1947 the German cosmetics firm Schwarzkopf launched the first home color product, "Poly Color". Eugène Schueller, the founder of L'Oréal, is recognized for creating the first synthetic hair dye in 1907.
The development of synthetic dyes for hair is traced to the 1860s discovery of the reactivity of para-phenylenediamine (PPD) with air. In the 1661 book Eighteen Books of the Secrets of Art & Nature, various methods of coloring hair black, gold, green, red, yellow, and white are explained. Others include katam ( buxus dioica), black walnut hulls, red ochre and leeks. Some of the most well known are henna ( Lawsonia inermis), indigo dye, Cassia obovata, senna, turmeric and amla. In ancient times, the dyes were obtained from plants. The dyeing of hair is an ancient art that involves treatment of the hair with various chemical compounds. Lafayette in 1830, aged 73, with pitch-black hair (painting by Louise-Adéone Drölling). Some of them are clean-shaven, but others-especially those of high rank-shave their cheeks but leave a moustache that covers the whole mouth.". They look like wood-demons, their hair thick and shaggy like a horse's mane. Their hair is blond, but not naturally so: they bleach it, to this day, artificially, washing it in lime and combing it back from their foreheads. They are very tall in stature, with rippling muscles under clear white skin. Diodorus Siculus, a Greek historian, described in detail how Celtic people dyed their hair blonde: