Marguerite Tuer-Sipos
Cannon Senior Editor

Unless this paper really is your sole source of news, it is more than likely you have already heard of the recent sale of a Leonardo Da Vinci painting, Salvator Mundi, for more than 450M USD. Just to clarify, that would be more than 563M CAD. As an engineering student it could be hard to imagine why an exorbitantly priced painting is pertinent to your undergraduate degree, however without developments in engineering technology it is unlikely the painting would have ever fetched such a price. Not only was technology essential in the authentication process of the painting, it uncovered new details about Da Vinci’s creative process and aided in the piece’s restoration. With a long and sordid history, including the addition of a moustache during the 1800s, authenticating the painting as a true Da Vinci was challenging. To authenticate a piece of art there are two major components of the creative process that must be validated; the material and the technique. The materials used in the painting must be congruent with both the artist’s typical choice of pigments and the availability of those pigments during the presumed time period. The technique used in the painting must match techniques used in the rest of the artist’s body of work. While the style and subject matter can only suggest the artist’s hand, material analysis and high-level imaging can objectively confirm parallels between the piece in question and other legitimate paintings. When discussing a possible Leonardo Da Vinci painting the stakes of the authentication climb.

Determining whether Salvator Mundi was a true Da Vinci was a particularly difficult authentication due to the nature of Da Vinci as an artist. Seemingly unable to be satisfied with a painting, Da Vinci finished very few pieces in his lifetime, and those he did were created with obsessive technique defined by many alterations. To authenticate Salvator Mundi as a true Da Vinci would be to add to a list of 16 paintings created by one of the most influential artists in human history. So what convinced a group of sceptical art historians that underneath the heavily damaged painting that lay before them was a brilliant work by Leonardo Da Vinci?

Mirroring the slow and methodical process of the Leonardo himself, the researchers analyzing Salvator Mundi painstakingly combed through the painting to build an impenetrable wall of proof about the painting’s authorship. Taking macroscopic samples of the paint revealed two clues about Salvador Mundi’s origins. Christ’s blue robe was painted using a pigment called lapis lazuli, a significant discovery since this was the most expensive pigment during this time period and would have thus been available to only the most skilled painters. Even more interestingly, this is the only painting in which Da Vinci used the precious pigment, perhaps indicating how highly he himself valued this particular piece.  The care he took to create the flesh tones in Salvator Mundi echo this elevated interest. Through a cross-sectional examination of the paint fragments on Christ’s hand, the technique Da Vinci used is uncovered. A total of five layers of paint were carefully overlain to create the subtle highlights and shadows in the hands in order to emulate the warmth of real human skin. This delicate layering is emblematic of Da Vinci’s later style; a complicated technique seen only in two of his other works (Mona Lisa and St. John the Baptist), and never mastered by his students. The analysis of the painting’s materials however was only one half of the information needed to validate Salvator Mundi.

To confirm the painting was made at the hand of Da Vinci, more proof was needed. Infrared reflectography (IRR) was employed to look beneath the painting’s surface, in search for clues about what preceded the finished product. IRR is a common tool in the authentication and conservation of paintings. IRR takes advantage of the properties of paint pigment. Within the infrared wavelength range (700-2000nm), paint pigments approach transparency. While shining an infrared light on the painting, an infrared camera captures an image known as an infrared relfectogram. It is the infrared relfectogram of Salvator Mundi that cemented its status a true Da Vinci creation. By looking beneath the painting’s surface the extensive network of Da Vinci’s alterations was exposed. The infrared relfectogram revealed the initial position of Christ’s blessing hand had been more upright, and was later changed to achieve a more natural pose. Further, the angle of Christ’s left hand had been adjusted several times to best achieve the optical illusion of the crystal orb. The face of Christ contrasted this flurry of change; underdrawings visible in the relfectogram demonstrated almost no adjustments were made from Da Vinci’s initial plan. Overall the body of Christ was highly improvised while his head was carefully planned and meticulously executed. This combination, and mastery, of different techniques in one portrait was an indisputable relic of Da Vinci’s genius.

Through the analysis of microscopic paint fragments and the infrared relfectogram it was determined Salvator Mundi was the work of Leonardo Da Vinci. Without advances in technology this discovery would have never been made, and arguably one of Da Vinci’s most brilliant paintings would have remained an overpainted Jesus with a moustache.

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