Jacopo Prisco , CNN Written by

Artists in classical cultures such as Egypt, Mesopotamia, Greece and Rome were known to paint with a variety of hues -- a practice known as polychromy (from Greek, meaning "many colors.") So why do we always think of antiquities as colorless?

The myth of the white marble started during the Renaissance, when we first began unearthing ancient statues. Most of them had lost their original paint after centuries of exposure to the elements, and contemporary artists imitated their appearance by leaving their stone unpainted.

The trend continued into the 18th century as excavations brought more and more artworks to light. That's also when Johann Joachim Winckelmann , who many consider the father of art history, literally wrote the book on ancient art, framing our modern view of it. Although he was aware of the historical evidence that sculptures were once colorful (some discoveries even had some paint left on) he helped idolize whiteness.

"The whiter the body is, the more beautiful it is as well. Color contributes to beauty, but it is not beauty. Color should have a minor part in the consideration of beauty, because it is not (color) but structure that constitutes its essence," he wrote.

This statue of a lion from 350 BC is colorless now, but was almost surely painted with offsetting colors for the body and the mane. Credit: Fine Arts Museum of San Francisco

But for over a decade, " Gods in Color ," a traveling exhibition whose main findings have been collected into a book , has offered the public a chance to see these statues as the ancients would have seen them, staging precisely rendered, full-color reproductions.

"This exhibition introduces the message that sculptures were painted often with dazzling and garish colors, with reconstructions of what they might have looked like, based on the colors and pigments that were available at the time," Renee Dreyfus, a curator for the exhibition, said in a phone interview.

Looking for "paint ghosts"

The research of Vinzenz Brinkmann, an archeologist and professor at Frankfurt's Goethe University, coalesced in the original "Gods in Color" show at Munich's Glyptothek museum in 2003.

To create reproductions, Brinkmann starts by simply looking at the surface of the sculptures with a naked eye, before adding various visual aids in the form of ultraviolet of infrared lamps. The light source must come from a very low angle, nearly parallel to the surface being analyzed. That simple trick brings out details otherwise impossible to see.

Because paint acts as a coating and wears off unevenly, bits of surface that were covered in paint will stand out as they were protected from erosion.

"That can show a variety of different paints that are there or are gone, but have left a paint ghost," Dreyfus said.

This "paint ghost" can help researchers deduce the original paint patterns on the statue. It can also help in understanding what types of pigments might have been used, as more resistant ones would have lasted longer than weak ones.

"We can also grind minuscule amounts of the original pigment, where present, and determine what its color was," Dreyfus said.

Artistic impressions

Most ancient pigments were derived from minerals, some of which were toxic. (Natural cinnabar, the most popular red color in the ancient world, for example, came from mercury.) To make paint, the pigments were mixed with binders made from common items such as eggs, beeswax and gum arabic.

The paint could then be applied directly onto smooth surfaces like marble, or after a primer made of chalk or stucco used to smooth out uneven materials. A layer of polish was often the last step, applied by wrapping a wax candle in a linen cloth and rubbing it on the statue.

By reverse-engineering these steps, Brinkmann developed a technique to recreate the colors with a good level of confidence. Until recently, a cast of the original had to be created with plaster, but now a laser scan is performed and an exact copy is 3D-printed. But that doesn't mean that the reproductions are completely authentic.

"It's not at all clear if this is the way they actually looked, but there's no question that we know exactly where the pigments were, and that's a great step forward," said Dreyfus.

In the exhibition, many pieces were juxtaposed to their originals, creating a stark contrast between the whitewashed and the garishly colorful.

Luisa Ricciarini/Leemage/UIG via Getty/Courtesy Fine Arts Museum of San Francisco

"Most people have no idea that the originals were colored, and they are astounded by the reproductions," said Dreyfus.

In the end, these colored versions probably look as strange to today's museum visitors as the now-monochrome originals would look to our ancestors.