There is a toxic secret behind da Vinci’s Mona Lisa and Last Supper

Many paintings in the sixteenth century, like Mona Lisa, were painted on wood panels. This meant that there was a requirement of a thick “ground layer” of paint to be laid down before artwork could be added. Most artists used a white paint mixture known as “gesso.” But the new study published in the journal, Journal of the American Chemical Society, revealed that Da Vinci laid down thick layers of lead white pigment and an orange pigment that was made by infusing oil with lead oxide.

Leonardo Da Vinci’s Last Supper. (Wikimedia commons)

Da Vinci seemed to have used a similar technique on the wall under the “Last Supper.” Even this is a departure from the traditional techniques of the time.

The researchers performed advanced chemical analyses on a small “microsample” obtained from a hidden corner of the Mona Lisa and also 17 microsamples obtained from the surface of the Last Supper. Not only did they find oil and lead white, but they also found a very rare lead compound—plumbonacrite. This material has not been found in contemporary Italian Renaissance paintings before. Interestingly, it has been found in paintings made by Rembrandt in the 17th century.

According to the American Chemical Society, painters have been known to add lead oxide to pigments to help them dry in the past. But this is the first time that it has been proven experimentally that da Vinci used the toxic substance.

Consumption of lead oxide can cause abdominal pain, nausea, and vomiting in the short term while long-term exposure can have effects on blood, bone marrow, the central nervous system, peripheral nervous system and kidneys, according to the World Health Organisation. These effects could be anaemia, encephalopathy (for example, convulsions), peripheral nerve disease, abdominal cramps and kidney impairment.