So called "Egyptian blue" gives color to the night sky in paintings on the walls of Ancient Egyptians’ tombs. Its first use could be as early as 3200 B.C. making it possibly the first artificial pigment. The Romans and Greeks then borrowed the color, using it for example to paint the messenger goddess Iris in the Parthenon. But by the Middle Ages, the technique to make Egyptian blue was presumably lost, because it no longer appeared in paintings.
Now, research shows that the pigment perhaps first took a back seat before its disappearance, writes Greg Watry for R&D Magazine.
Egyptian blue was once thought to be reserved for painters looking to make something truly blue — it imitates the richness of the rare and more expensive pigment lapis lazuli. But researchers have found Egyptian blue lurking hidden in paintings that blend Greco-Roman and Egyptian styles. The pigment, far from being featured for its hue, was used for the underdrawings.
Researchers used near-infrared luminescence imaging to identify the pigments in the paintings from the second century A.D. The organic and inorganic compounds give off distinct signatures using this method. "This technique is very sensitive to the detection of Egyptian blue, even in amounts too small to be observed with the naked eye," the research team writes in their study, published in Applied Physics A.
The color blue isn’t visible, but the pigment is there. The artists could have been using the pigments glistening properties to modulate the colors they lay on top. However, perhaps the shift away from prizing the blue for its blueness caused the fabrication of Egyptian blue to fall to the wayside. Red, yellow and black became far more popular colors. When the Roman empire collapsed, Egyptian blue disappeared.
The story doesn’t end there, however. The same glistening properties that consigned the color to the background could make the pigment suitable for security inks or other applications. Egyptian blue could rise again.