Not believing that Dan Brown has unlocked the ultimate secret of the Mona Lisa, French researchers used X-ray fluorescence spectroscopy to study the famous painting and discovered something amazing:
Da Vinci used a renaissance painting technique called "sfumato," mixing thin layers of pigment, glaze and oil intricately to yield the appearance of lifelike shadows and light. The technique is well known and has been employed by other artists over the years. But only now have scientists been able to analyze just how intricate da Vinci's layers are.
They believe da Vinci used up to 30 layers of paint on his works. But altogether they only add up to a thickness of less than 40 micrometers of paint -- about half the width of a human hair.