Ancient Hair Dye Worked at Nano-Level

Oct. 2, 2006 — After re-creating a hair dye used during the Roman Empire, scientists have reported that the technique early Greeks and Romans used to color their hair had some things in common with modern nanotechnology.

The authors of a study in the current issue of the journal Nano Lettersnot only found that ancient hair dyes actually work, but that they are comparable to products, such as Grecian Formula, available today.

Since nanocrystals form within hair during the blackening, the findings also suggest quantum physicists could use hair, or hair-like fibers, to grow quantum dots — tiny controlled atoms — for use in high-tech lasers, sensors, computers and other devices.

This bridging of past and future technology began when Philippe Walter, a senior research scientist at the Research and Restoration Center of French Museums, collaborated with L’Oreal Research to study the history of cosmetic science. While researching the subject, Walter and his colleagues came across an old hair dye recipe.

"During the 2nd century A.D., Claudius Galen, the most famous doctor in the Roman Empire, precisely described the use of a mixture of lead oxide and slaked lime to dye hair black," Walter told Discovery News.

The researchers mixed these ingredients with water to form a paste. They then dyed blonde human hair with the paste mixture for three days. Each day they X-rayed the hair and magnified it using electron microscopy to see what was going on at the molecular level.

They discovered that the ingredients reacted with the protein building blocks in the hair to form sulfur, allowing the lead to penetrate hair shafts.

Analyzing the center of each strand of hair, the researchers observed the formation of tiny lead sulfide crystals, which lined up at just .00000003937 of an inch across. Since these crystals act somewhat like melanin, the natural substance that gives hair color, more crystals meant darker hair.

Walter explained that chemical engineering of such tiny structures to form quantum dots is "a current challenge in nanotechnology," and that the reaction of this ancient lead dye with hair exemplifies the sort of process that researchers are trying to develop.

In a separate study, scientists Bo Yang and Vinod Tewary at the National Institute of Standards and Technology came to similar conclusions about how self-assembling quantum dots line up, only their focus was on assemblages in semiconductor materials rather than hair.

Previously, Walter and his team studied 4,000-year-old Egyptian eye makeup housed at the Louvre Museum. They again found that lead was an important ingredient. In this case, lead chlorides and other compounds thought to confer medicinal properties, such as clearing up infections, were added to a lead sulfide base.

The Egyptians, it seems, believed a heavy application of eye makeup served double duty as both a beauty enhancer and medicine.

The 2,000-year-old Greek and Roman hair dye, however, probably was for looks only. In addition to black dye, many individuals dyed their hair red with henna and sprinkled it with gold powder and often a fresh flower or two. Hairdressing and barbershops were located in most populated regions of the ancient world.