Leonardo da Vinci: An amazing discovery
What secrets lie underneath the surface of Leonardo’s ‘Virgin of the Rocks’?
The Virgin of the Rocks by Leonardo da VinciThe National Gallery, London
This is one of Leonardo da Vinci’s most mysterious and complex pictures 'The Virgin with the Infant Saint John the Baptist adoring the Christ Child accompanied by an Angel' ('The Virgin of the Rocks'). But what lies underneath the surface of the painting?
At the National Gallery there is a long tradition of using the most advanced analytical and imaging techniques to study how paintings were made.
Early discoveries
In 2004, a team of conservators, scientists and curators first used infrared reflectography (an imaging technique used to 'see through' layers of paint) to investigate the painting, hoping to uncover what was invisible to the human eye.
‘The Virgin of the Rocks’ by Leonardo da Vinci: infrared reflectogramThe National Gallery, London
The team discovered that numerous lines – referred to as underdrawing – had been drawn by Leonardo to lay out the composition for the painting.
In several areas Leonardo did not entirely follow these lines while painting. For example, some long, wavy locks of hair drawn around the angel’s face were never painted in.
More surprisingly, the team also found underdrawing for a completely different design which Leonardo had abandoned in favour of the composition we see in the painting today.
Just above the halo of the Virgin, we can see the underdrawing for the head of another figure.
The part of the head that is most clearly visible is the figure's right eye (almost touching the halo). If we look a little further down, around the Virgin's chin, we can also see a hand.
This is the diagram of all the lines thought, at this time, to be linked to the abandoned composition. The diagram shows that there was a larger scale female figure in the centre of the abandoned underdrawing.
The position of the female figure's head, gazing gracefully to the right, as well as her outstretched right arm and left hand suggested that she might be a Virgin adoring a Christ Child - but this could not be confirmed.
‘The Virgin of the Rocks’ being investigated by X-Ray Fluorescence (XRF) scanningThe National Gallery, London
A mystery solved
This mystery remained unsolved until 2019 when the painting was re-investigated using two cutting-edge spectroscopic imaging techniques: X-Ray Fluorescence (XRF) scanning (pictured here) and Reflectance Imaging Spectroscopy in the shortwave infrared (SWIR-RIS).
X-Ray Fluorescence (XRF) scanning
XRF scanning is used to map the distribution of chemical elements in paint, both at and below the surface of a painting. This technique provides insight into the pigments and techniques used by an artist and helps us to see any changes made during the course of painting.
‘The Virgin of the Rocks’ by Leonardo da Vinci: X-Ray Fluorescence (XRF) map of zincThe National Gallery, London
This XRF map indicates where the element zinc is present. As zinc is a fairly common impurity in the natural blue pigment azurite, we can see where this pigment has been used. For example, in the underpaint for the Virgin's robes and in the distant mountains and lake.
Unexpectedly, the underdrawing lines for Leonardo's first abandoned composition also contain zinc. The signal is quite low, but it is possible to see the profile of the larger-scale Virgin in the XRF zinc map.
Even more remarkably, the zinc map also reveals that the Virgin is looking at the Christ Child, who is supported by a front facing angel.
SWIR-RIS
Some of the lines for these figures are emphasised in images produced from the processing of data collected by another imaging technique - Reflectance Imaging Spectroscopy in the shortwave infrared (SWIR-RIS).
Combining imaging techniques
The poses of the Christ Child and angel become even clearer in this diagram that combines all the lines seen in the different technical images of the painting.
Diagram of the first abandoned composition hidden underneath ‘The Virgin of the Rocks’ (2019-20)The National Gallery, London
It took a long time to study all the different technical images, trying to identify exactly which lines belonged to Leonardo’s abandoned composition...but we now have a much better idea of what he had initially sketched on the panel.
The Virgin of the Rocks by Leonardo da VinciThe National Gallery, London
These new findings can now be compared with other paintings and drawings by Leonardo, providing exciting food for thought when trying to understand the complex genesis of this exquisite painting.
