A portrait drawn by Leonardo da Vinci in the early 1500s that is in poor condition is being evaluated by researches.
The drawing has been damaged from enduring centuries of humid storage conditions, an Applied Physics Letters news release reported.
"During the centuries, the combined actions of light, heat, moisture, metallic and acidic impurities, and pollutant gases modify the white color of ancient paper's main component: cellulose," Joanna Łojewska, a professor in the Department of Chemistry at Jagiellonian University said in the news release. "This phenomenon is known as 'yellowing,' which causes severe damage and negatively affects the aesthetic enjoyment of ancient art works on paper."
In order to determine if the red chalk drawing is still degrading or is being appropriately conserved researchers looked at light-absorbing molecules called chromophores. These molecules are what cause the "yellowing" of the paper.
"[Yellowing occurs when] chromophores within cellulose absorb the violet and blue range of visible light and largely scatter the yellow and red portions -- resulting in the characteristic yellow-brown hue," Olivia Pulci, professor in the Physics Department at the University of Rome Tor Vergata said in the news release.
The researchers created a method to" identify and quantify" the concentration of chomosphores in the drawing without further damaging it.
The team used a reflectance spectroscopy setup to look at the optical reflectance of the paper samples in the "near-infrared, visible, and near-ultraviolet wavelength ranges," the news release reported.
"Using our approach, we were able to evaluate the state of degradation of Leonardo da Vinci's self-portrait and other paper specimens from ancient books dating from the 15th century," Adriano Mosca Conte, a researcher at the University of Rome Tor Vergata said in the new release. "By comparing the results of ancient papers with those of artificially aged samples, we gained significant insights into the environmental conditions in which Leonardo da Vinci's self-portrait was stored during its lifetime."
