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The mystery of Hubert van Eyck and the Ghent Altarpiece solved ‒ Interdisciplinary study of the research data of the second restoration phase

In collaboration with the University of Antwerp, our interdisciplinary team conducted an in-depth study of the evidence gathered during the restoration of the lower register of the opened Ghent Altarpiece (2016-2019). They succeeded in uncovering one of the greatest mysteries in art history: the precise contribution of Jan van Eyck and his illustrious older brother Hubert van Eyck to the creation of the Ghent Altarpiece.

University of Antwerp
Fondation Périer-D'Ieteren

In 2012, the Royal Institute for Cultural Heritage initiated a large-scale restoration campaign of one of the world's most iconic works of art: the Ghent Altarpiece by the Van Eyck brothers (1432), which was created for Saint Bavo's Cathedral in Ghent and is still kept there. The last two phases of treatment - of the closed polyptych (2012-2016) and the lower panel of the opened polyptych (2012-2019) - have already resulted in several unexpected discoveries, including the revelation of the original painting by Jan van Eyck. This stunning painting had been hidden for centuries under overpainting from the 16th century. Today, you can admire it once again. Moreover, the team was able to demonstrate the authenticity of the famous quatrain on the frame and reveal the original polychromy.

The first two stages of the restoration campaign were funded by the Flemish Government and the Fonds Baillet Latour and carried out by the Royal Institute for Cultural Heritage in a room at the Museum of Fine Arts (MSK) in Ghent. A committee of international experts supervised these stages. The research, with contributions from the universities of Ghent and Antwerp, was supported by the Gieskes-Strijbis Fund (Amsterdam).

The quatrain and the mystery of Hubert van Eyck (†1426)

In 1823, beneath an over-painting, a verse was found that contains crucial information on the origin of the masterpiece. The Latin text says: "The painter Hubert van Eyck, a greater man than whom cannot be found, began this work. Jan, his brother, second in art, completed the weighty task at the request of Joos Vijd. He invites you with this verse, on the sixth of May [1432], to look at what has been done." Since then, the figure of Hubert van Eyck has captured the imagination of many generations of art scholars.

In the past two centuries, the quatrain gave rise to numerous hypotheses about the creation of the Adoration of the Mystic Lamb and the precise contribution of both brothers. We know that Hubert died in 1426, probably during the creation of the Ghent Altarpiece. However, no other paintings by him are known, and his precise contribution remained a great mystery.

In 2020, authors who dismissed the quatrain as an unreliable late addition were proved wrong: our restoration team demonstrated that the inscription is authentic. This discovery was a new impulsion to unravel the precise contribution of Hubert and Jan van Eyck to the Mystic Lamb. The current breakthrough is based on intense interdisciplinary cooperation and a thorough analysis of considerable data. For years, the restorers were in close daily contact with the paintings and recorded numerous detailed observations, including under a stereoscopic microscope. They could also rely on new scans with infrared reflectography and, thanks to the contribution of the University of Antwerp, also with macro X-ray fluorescence (MA-XRF). These were created after the 16th-century overpainting had been removed, allowing us to look deeper into the underlying paint layers. Other cornerstones of the research are high-tech lab analyses of paint samples, art-historical studies and comparative stylistic examinations.

That Hubert van Eyck painted parts of the Adoration of the Mystic Lamb is thus, for the first time, demonstrated based on stylistic studies and scientific data. Therefore, his contribution was not merely limited to the planning and the design, as was frequently suggested.

It is with great pride that I have discovered these stunning new results, along with all lovers of the Ghent Altarpiece. I warmly encourage everyone to come and admire this splendid work in Saint Bavo's Cathedral or on the Closer to Van Eyck website.

Thomas Dermine, State Secretary for Science Policy

Who painted what?

A relatively elaborate underlying painting was found on the central panel with the Altarpiece, which, thanks to the quatrain, can be attributed to Hubert van Eyck. He painted the sky, a hilly landscape with fewer buildings, cities on the horizon and a meadow. The altar with the Lamb and Angels and some of the central figures are already present in that first painting. A natural spring was painted in the meadow in front of the altar.

In a second phase, probably painted after Hubert's death in 1426, we have distinguished the hand of Jan van Eyck. He completed and overpainted a large part of his brother's work but left some pieces untouched. The central motif of the natural spring was painted over with the monumental fountain we see today. Jan meticulously painted around some of Hubert's central figures, retouched some, and added others.

Jan van Eyck also painted over the landscape, adding more details and the unprecedented variety of vegetation visible today. He added one layer of azure blue in the sky and the colourful halo. Jan also reworked Hubert's first composition depicting cities on the horizon. He added, among other things, the motifs in which one recognises the tower of Utrecht Cathedral, the former St Bavo's Abbey and the Church of Our Lady in Bruges.

A third intervention

Finally, the investigation showed that a number of details were added in a third stage. It was then that the gilded rays were applied, and the dove of the Holy Spirit was enlarged. Details were added or reworked in the vegetation, the buildings, and some figures. Although we cannot rule out the possibility that this was the work of one or more assistants, these adjustments were probably only made after the death of Jan van Eyck (in 1440), but still before the large overpainting from the middle of the 16th century.

Pigments and techniques of the Van Eycks unravelled

Our Polychrome Artefacts Lab set up a parallel research project, which analysed the paint with a wide range of high-tech techniques (HPLC, SEM-EDX, Raman and infrared spectroscopy). They even had some samples studied using synchrotron (ESRF, Grenoble). The AXIS research group (University of Antwerp) also contributed to MA-XRF and MA-XRPD scans. The combination of all these results led, among other things, to the discovery of surprising dye additives such as finely ground colourless glass. Moreover, Van Eycks' use of zinc sulphate as a drying agent, as mentioned in 15th-century recipe books, was confirmed in numerous layers and zones in the painting.

New perspectives

The current discoveries open the door to a new chapter in the study of the Flemish Primitives: the search for other paintings by Hubert van Eyck. He possibly forms the 'missing link' between pre-Eyckian painting and the radically innovative Ars Nova of his younger brother Jan van Eyck. After all, Jan's mastery appears as if from nowhere with the Ghent Altarpiece.

Meanwhile, it is a fresh starting point for studying the Altarpiece paintings that have not yet been restored or analysed using new research techniques. The cathedral church council is launching a public auction for this third and final phase. Funding has already been pledged by the Vlaamse Departement Cultuur, Jeugd en Media and the Flanders Heritage Agency (80%) and the Fonds Baillet Latour (20%). The restoration will get underway in 2022.

The book

All discoveries and the progress of the restoration of the lower register of the opened Ghent Altarpiece are described in the book The Ghent Altarpiece. Research and Conservation of the Interior: The Lower Register. The restoration team, the labs and image specialists of the Institute (KIK-IRPA), together with the scientists of the AXIS and ARCHES research groups (University of Antwerp), are responsible for this richly illustrated scientific publication. It was produced with the support of the Fondation Périer-D'Ieteren.

Seeing the Ghent Altarpiece in Saint Bavo's and online

In the visitors' centre of St Bavo's Cathedral, you can admire the restored panels of The Adoration of the Mystic Lamb and various other authentic art treasures in all their splendour. With the help of augmented reality glasses, you can travel deep into the past in the cathedral's crypt and experience the eventful history of the Altarpiece and Ghent Cathedral as if you were there. The masterpiece and the imposing building come to life in all their glory.

More info and tickets

On the website Closer to Van Eyck, you can zoom in on high-resolution images of the Ghent Altarpiece and of other paintings by Jan van Eyck and his studio.

Source images: Sint-Baafskathedraal Gent,, photos KIK-IRPA

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