First step towards restoration: the Passion Retable under the microscope

First step towards restoration

the Passion Retable under the microscope

In the Middle Ages, almost every church in Leuven had several altarpieces or retables. Many of these have been lost, but a beautifully carved 16th-century example can be seen in the ‘Collection of M’: the Passion Retable.

Stijn Lenaerts is conservator of polychromed artefacts at the restoration and conservation company IPARC. Over the past few months, he has thoroughly examined the altarpiece in the exhibition space. Visitors were able to follow the process step by step.

Stijn: “The altarpiece depicts Jesus’ suffering and death, or the Passion. Underneath are scenes from his childhood. We believe it was made in Antwerp and dates from around 1520. It was first hung in the chapel of the Augustinian convent on what is now the Hertogensite. Over the centuries, however, it made quite a journey through Leuven before reaching M’s predecessor, the Stedelijk Museum Vanderkelen-Mertens. We’re investigating the work with a view to restoration. Museum curators are carrying out art-historical research in archives and related sources, while I’m conducting material-technical research on the actual altarpiece.”

“The first step was to take highly detailed photographs with a special camera. Using natural and ultraviolet light, we made two sets of images. These revealed a thick layer covering the entire surface. It dates back to the late 1960s when Jan Crab, the former curator of the Vanderkelen-Mertens Museum, restored the altarpiece. He removed centuries-old overpainting, amongst other things, before applying a layer of wax to the surviving, original colours. This was common practice at the time. It is both a blessing and a curse: the wax does its job well, but it also attracts dust. Consequently, the figures and the cabinet now look rather dull.”

Detailfoto van het Passieretabel in museum M Leuven — © IPARC

Colour codes

“The remainder of the investigation consists of a thorough visual inspection. We examine all parts of the altarpiece and check for damage, for new pieces of wood that have been inserted, for traces of overpainting, and for missing elements. We input the information into a computer programme and all the findings are colour-coded and marked on the photographs. It’s painstaking work.”

“This kind of material-technical research is important in its own right, but it is also essential for the restoration. Experts determine how to proceed based on the results.”

Onderzoeker bij het passieretabel van museum M Leuven — © Elias Derboven voor M Leuven

“My research is mainly visual. However, I am also conducting cleaning tests on several fragments. This will enable us to determine which method is most suitable for the actual restoration. It will also allow us to establish what remains of the original polychromy beneath the overpainting. To this end, I have removed two scenes from the altarpiece and studied them under a microscope. We will need to dismantle them all during the restoration. It will augment our understanding of the altarpiece.”

Het Passieretabel in museum M Leuven — © Elias Derboven voor M Leuven

The Passion retable in museum Leuven — © Elias Derboven for M Leuven

Passion for altarpieces

Through their contributions in 2025, our M-cenas members are continuing to make the Passion Retable restoration and research project possible. We also look forward to involving them in this initiative over the coming years.

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