In 2014, French optical engineer Pascal Cotte published the results of a three-year technical investigation into Leonardo da Vinci's Renaissance art portrait Lady with an Ermine. Using a technique he developed called the Layer Amplification Method (LAM), Cotte projected intense multi-spectral light onto the walnut panel at the Czartoryski Museum in Kraków and measured the reflections across 240,000 wavelengths. By analyzing how light penetrated successive layers of paint, Cotte was able to reconstruct the sequence of brushstrokes beneath the visible surface without taking a single micro-sample from the work.
Three Drafts on a Single Walnut Panel
The multispectral data showed that Leonardo did not execute the portrait in a single continuous campaign. Instead, the composition evolved across three distinct physical phases.
In Stage 1, Leonardo painted sixteen-year-old Cecilia Gallerani alone. Her posture, red velvet dress, and coiled hair were already established, but her hands were folded quietly across her waist with no animal present. The portrait functioned as a conventional court likeness of Ludovico Sforza's favorite mistress, painted shortly after her arrival at the Milanese court in 1489.
In Stage 2, Leonardo revised the composition by adding a small, slender animal with grey fur. The creature rested across Gallerani's forearm, but its proportions were modest and its muscular structure lacked definition. Cotte's scan revealed that Leonardo had altered the sleeves of Gallerani's dress to accommodate the new figure, adjusting the folds of yellow and blue fabric.
In Stage 3, Leonardo painted over the grey animal, replacing it with the large, muscular white creature seen today in modern reproductions and canvas art prints. He expanded the torso, deepened the chest, and reshaped the head, giving the animal a formidable, heraldic posture, creating a striking centerpiece among animals wall art depictions. Leonardo also repainted Gallerani's right hand, elongating the fingers and accentuating the tendon structure to convey a firm, protective grip on the animal's back.
Symbolic Puns and Court Politics in Milan
The evolution from an unadorned portrait to the final composition aligns with political and heraldic developments at the Sforza court in Milan between 1489 and 1491.
The ermine carried dual symbolic weight. In classical Greek, the word for ermine is galē, creating an intentional visual pun on Cecilia Gallerani's family name. At the same time, Ludovico Sforza had been inducted into the prestigious Order of the Ermine by King Ferdinand I of Naples in 1488, subsequently adopting the white ermine as his personal heraldic badge and nickname, L'Ermellino.
Art historian Martin Kemp of Oxford University noted that Cotte's technical findings demonstrate how Leonardo negotiated the shifting demands of his patron. By adding the white ermine in Stage 3, Leonardo transformed a private portrait of his patron's mistress into a sophisticated political emblem, visually uniting Cecilia Gallerani with Ludovico Sforza just as Sforza was preparing for his dynastic marriage to Beatrice d'Este in January 1491.
The Lost Atmospheric Background
Cotte's multispectral scans also resolved a long-standing debate regarding the flat dark background surrounding Gallerani, a motif often echoed in modern black wall art framing. Technical analysis confirmed that Leonardo originally painted a luminous, modeled background in shades of bluish-grey, establishing spatial depth behind the sitter's shoulder.
Cross-sectional examinations indicated that the solid black overpaint was applied centuries later, likely during the 18th century after Prince Adam Jerzy Czartoryski purchased the painting in Italy around 1800. The overpainting removed Leonardo's subtle atmospheric shadows and obscured a window or doorway opening that originally occupied the upper left corner of the panel.
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