Organic hair dyes from plants, such as henna, were commonly used for human hair, and have been used up to modern times. However, some unusual formulas using lead compounds were also used to dye hair and wool black. Technology for permanently coloring hair has not attracted the attention of researchers and companies, but remains as the prime need of every old people.
Study
Recently, studies of scientists in France on the use of lead salts for hair darkening have shown that lead sulfide nanocrystals form inside a hair during the dyeing procedure. These lead sulfide crystals that form are 5 nanometers in diameter and appaear to be very similar to the lead sulfide quantum dots that are being synthesized by modern scientists. However, unlike modern technology, the dyeing process uses basic chemistry methods and low-cost natural materials. By studying this process of synthetic nanoscale biomineralization in hair, scientists have better understood how to grow and organize nanoparticles for other uses.
Most permanent hair coloring technology is based on an old approach that uses p-phenylenediamine (PPD), a chemical that produces darker, browner shades when exposed to air. Concern over the safety of PPD and other hair dye ingredients, and demand for more convenient hair dyeing methods, has fostered an upswing in research on new dyes and alternative hair coloring technologies.
Future techniques
Future hair coloring techniques include nano-sized colorants which will penetrate the hair and remain trapped inside for longer-lasting hair coloration. Scientists also are developing substances that stimulate the genes to produce the melanin pigment that colors hair. These substances promise to produce a wider range of more natural-looking colors, from blond to dark brown and black without toxicity but with more natural results.
Natural herbal hair dye
A commercial natural herbal hair dye (nanotech Chinese knotweed extract) has a special formula to protect hair, time-efficient, and is easy to use. It does not contain ammonia, odorless, and has no side effects. With natural pigment extracted from Chinese knotweed directly from the plant, the hair dye offers natural and appealing color. Other ingredients are Henna powder, tea leaves, p-Phenylenediamine, and lemon essential.