Leonardo da Vinci: after the Salvator Mundi a ‘new’ San Girolamo resurfaces

Gianluca Poldi

Leonardo da Vinci’s Salvator Mundi was in a bad shape. The same goes for his drawing representing San Girolamo. Scientists have brought them back to life.

Just when you thought there was nothing more to discover about the over-studied Leonardo da Vinci, proper scientific research proves exactly the contrary. This is what recently happened to me after the analysis of some drawings by Leonardo and his assistants from the end of the 15th century/beginning of the 16th, belonging to the collection of the Veneranda Biblioteca Ambrosiana and including a few from the Codex Atlanticus. These drawings are currently on display at the Pinacoteca Ambrosiana, in the context of an exhibition curated by Benedetta Spadaccini, which featured 80 plus drawings by artists from the school of Leonardo (Boltraffio, Marco d’Oggiono, Bernardino Luini, Agostino da Lodi among others) and focused on the drawing techniques and styles taught at the master’s studio.

A new drawing by Leonardo da Vinci

Among the most important discoveries in the exhibition are worn out sheets, especially a small picture of San Girolamo (47×42 mm) that sheds light on how Leonardo da Vinci approached the subject beside what can be concluded from the fantastic yet unfinished panel at the Vatican Museums. UV Fluorescence images of this small pen drawing of the kneeling saint, sketched with iron gall ink reveal how the body is portrayed: the left arm stretches to reach for the thin cross, while the saint hits his own chest with a rock held with the other hand.

Leonardo da Vinci, Saint Jerome in penitence, Pinacoteca Ambrosiana, inv. F274 inf. n. 34c. Visible light and UV Fluorescence image. © Biblioteca Ambrosiana and Gianluca Poldi.

Another remarkable piece in the exhibition is the drawing of a woman’s head by the Maestro della Pala Sforzesca, somewhat of a late Gothic painter that nonetheless mastered drawing under the influence of his teacher Leonardo. Despite the fact that this work on beige coated paper is almost entirely lost today, UV images of it show the artist’s great chiaroscuro skills, with shades that were probably realised directly with his finger or a sponge.

Maestro della pala sforzesca, Study of female head, Pinacoteca Ambrosiana,
inv. F263 inf. n. 63. UV Fluorescence b/w image. © Biblioteca
Ambrosiana and Gianluca Poldi.

The Bruker M6 Jetstream XRF scanner

The Bruker M6 Jetstream XRF scanner and spectrometer is but one of the instruments that allowed a clear visualisation of how the chemical elements were distributed on the support of the artwork, revealing some otherwise unreadable graphic characteristics and the types of inks used. Perhaps employed to scan drawings of this age for the first time, this machine and its remarkable precision (approx 10 micron, that is hundredths of a millimeter) was crucial in the investigation of the thinnest metal-point marks on paper.

Undoubtedly, Leonardo da Vinci’s metal-point drawing skills were unmatched. He used gold and silver-point (a copper alloy) for the most refined sheets, or lead and tin point for rougher, quicker sketches. The analysis of his pictures of some detailed man’s heads has shown that he especially favoured lead-point and black marks for the basic preparation of more complex drawings, which were eventually completed with a pen.

Leonardo da Vinci, Man with a hat, Pinacoteca Ambrosiana, inv. F263 inf. n. 87. Visible light and IR-Reflectography. © Biblioteca Ambrosiana e Gianluca Poldi.
Leonardo da Vinci, Man with a hat, Pinacoteca Ambrosiana, inv. F263 inf. n. 87. XRF map. The two images on the left show the use of iron gall ink containing zinc; the two images on the right show some lines drawn with lead-point under the main drawing. © Gianluca Poldi.

Metal-point drawing requires the paper to be coated in order for the tool to leave a mark on the surface. These marks can range from grey or brownish/grey to black for lead-point, with white, blue, red, rose, and sometimes beige paper coats.

When it comes to drawing, Leonardo da Vinci was a tireless experimenter. He not only put all that came to his vivid mind onto paper through sketches and writings, but he also challenged himself with all the drawing techniques available at the time, as well as inventing his own. For example, he was the first to use red pencil on red coated paper, subtly playing with those hues to make the figures emerge. This delicate technique would sometimes require a second passage with a pen to reinforce the outlines, allowing the artist to go back to the same work for a different reading after some time had passed.

Drawing at Leonardo da Vinci workshop

Leonardo’s use of pastel colours was possibly inspired by the work of Frenchman Jean Perréal, also known as Jean de Paris and mentioned by Leonardo in the Codex Atlanticus in the passage dubbed Memorandum Ligny (also on display in the exhibition at Pinacoteca Ambrosiana). Leonardo was able to perfect the technique of pastels to the point where many 16th century artists would adopt it thanks to him, including the skilled Giovanni Antonio Boltraffio, who was one of his most gifted pupils and allegedly his closest collaborator in the realisation of the popular Salvator Mundi. 

Leonardo would also extensively enjoy the silverpoint drawing technique, often combining it with blue coated paper. The use of this expensive instrument, sometimes referred to as the “scratch,” is documented by the artist himself in a note about the theft of the tool from Boltraffio’s studio by the young apprentice Gian Giacomo Caprotti da Oreno, also known as Il Salai:

On April 2, having left his silver scratch worth 24 coins on top of a drawing, Gian Antonio [Boltraffio] was robbed of it by Giacomo

Gian Giacomo Caprotti da Oreno was a recidivist apprentice indeed, as Il Salai had stolen another silverpoint from Marco d’Oggiorno just a few months earlier.


Salvator Mundi by Leonardo da Vinci: is it a restoration masterpiece?

The work of a restorer has never been rated as much as in the case of Leonardo Salvator Mundi, sold at Christie’s on 15th November 2017. Lets assume it makes sense to calculate the price of a work of art per square meter. Paying 450.3 millions dollar – auction house fees included – for a painted wooden board measuring 65.5 x 45.1 cm means that every squared centimeter of that painting costs you $154.000. The price of course embeds the “not Leonardo” parts, hence the parts retouched by Dianne Dwyer Modestini, who masterly restored the piece.

Leonardo da Vinci
Leonardo da Vinci, Salvator Mundi, c.1500, oil on walnut, 45.4 × 65.6 cm.

The authenticity issue

We are not questioning the painting’s authenticity: stylistically and technically speaking this Salvator Mundi is coherent with Leonardo da Vinci’s practice, nevertheless we can’t exclude some of his best pupils played a role in the making of it – someone suggested Boltraffio. Luke Syson, who curated the smashing exhibition dedicated to Leonardo at the London National Gallery in 2011, personally described the work in the exhibition’s catalogue attributing it to he master. Pietro Marani, a distinguished expert on Leonardo, confirms that The Salvator Mundi, now in the property of the Government of the United Arab Emirates, is an autograph painting by Leonardo da Vinci, even if he points out the work is not in a perfect state of preservation. Precisely Syson wrote that the “re-emergence of this picture, cleaned and restored to reveal an autograph work by Leonardo, […] comes as an extraordinary surprise”. But in the above mentioned catalogue he also wrote that the “reasons for such abundant over-paint are also clear: though both hands are well preserved, elsewhere the picture has suffered” and “it has also been aggressively over-cleaned, with some abrasion of the whole picture surface and especially in the face and hair of Christ”.

Leonardo Salvator Mundi
Leonardo da Vinci, Salvator Mundi, c.1500, oil on walnut, 45.4 × 65.6 cm. Detail.
Leonardo da Vinci
Leonardo da Vinci, Salvator Mundi, c.1500, oil on walnut, 45.4 × 65.6 cm. Detail.

What scientific analysis say

As proved by the image published in the ‘vanity catalogue’ dedicated by Christie’s to the fabulous lot (apparently they were expecting to sell it in the area of 100 millions), the recent cleaning revealed a long vertical crack and other evident losses of painted surface. They probably were due to the movement of the wood occurred during the centuries. The painting’ state of conservation is clarified by the technical images carried out by Art Analysis & Research, who produced Infra-Red Reflectography and X-Rays Radiography.

Leonardo Salvator Mundi
Leonardo Da Vinci, Salvator Mundi, Infra-Red Reflectography.
Leonardo Salvator Mundi
Leonardo Da Vinci, Salvator Mundi, after cleaning.

As many other works by the master, Leonardo da Vinci’s Salvator Mundi was painted on a walnut support; and not on a poplar one, generally employed by Italian artists at that time. IRR shows the lack of painting in many areas and also some small changes. There’s a little shift in the right hand thumb and some variations in the border of the cross-band on the chest and on the central decoration. Technically, we may affirm that the attribution to Leonardo is coherent with the results of the scientific analysis; but this coherency doesn’t rely on the use of high quality natural ultramarine (lapis lazuli), as someone stated; it is known that many other masters at that time were using the same kind of pigment. Rather, the painting is to be attributed to Leonardo on account of: a) under-drawing; b) the peculiar layering of pigments; c) the type and quality of the brushstrokes, which are perfectly fused together in the original and better preserved areas.

Leonardo da Vinci
Leonardo da Vinci, Salvator Mundi, c.1500, oil on walnut, 45.4 × 65.6 cm. Detail.

The role played by Dianne Dwyer Modestini

Having said so, would it be possible to account how much of lost painted surface was retouched during the restoration? According to the images available, we may estimate that more than 10% of the original painted surface of Christ’s face, neck, hair, dress and black background is by the hand of the restorer. Leonardo and the previous owner of the painting thank Dianne Dwyer Modestini. She had an impressive ability in recreating Leonardo’s ‘sfumato’ where needed, cleverly ‘interpreting’ what survived of the original image. The face of Leonardo Salvator Salvator was surely more simple to integrate than the Christ’s head of the Last Supper in Milan, whose interpretation of the shadows and of the whole head is still not convincing. But now that question is, what would be the price of the retouched parts of this extraordinary painting? Or, to put it in another way, how much would you pay for a 10% of a Leonardo by a distinguished restorer such as Dianne Dwyer Modestini?

Dianne Dwyer Modestini.
Dianne Dwyer Modestini.

January 18, 2020