The Ghent Altarpiece

The museum and collection

The Ghent Altarpiece (or the Adoration of the Mystic Lamb, Dutch: Het Lam Gods) is a very large and complex 15th-century Early Flemish polyptych altarpiece in St Bavo’s Cathedral, attributed to the brothers Hubert and Jan van Eyck. It is considered a masterpiece of European art and one of the world’s treasures. The restoration of The Ghent Altarpiece started at MSK Ghent in October 2012, where it was executed by the Royal Institute for Art Patrimony (KIK) in the very heart of the museum. After the restauration was completed, the altarpiece returned to St Bavo’s Cathedral.

The assignment

The display case for the Mystic Lamb was designed as a robust climate chamber for the polyptych. The display case, 6 m high and 100 m3 in size, is installed in the Chapel of the Blessed Sacrament. This is the largest, easternmost chapel in the ambulatory of St Bavo’s Cathedral in Ghent and is part of the tour in the new visitor centre.

In the display case, the altarpiece stands on an altar. It is suspended from a steel support structure, which is pneumatically controlled to allow the movement of the side panels without the sexton entering the display case. Every morning and evening, the side panels are slowly opened and closed, a magical moment that medieval people rarely got to experience. There are large burglar-proof doors that allow for easy evacuation of the wooden panels in the event of an emergency.

The project: challenges & results

The design was a lengthy multi-disciplinary process to find the right balance between the comfort of the visitors, the climate requirements, the heritage aspects, the religious context and the preconditions of the designers and builders of the showcase. The Flemish Council of Masterpieces watches over the good preservation conditions and formulated the preconditions for the tight climate conditions for the conservation.

The cathedral is not heated and the temperature can drop to 2°C in winter. Sunlight enters the Blessed Sacrament Chapel through the beautiful coloured stained-glass windows. It is quite a challenge to meet the climate requirements of the Top Council under these non-museum conditions. The bright light through the stained-glass windows can be screened by curtains, so that visitors can enjoy all the details of the artwork under ideal conditions.
The colour fastness of the burglarproof glazing ensures a true colour perception.

It is also these heated glass panels that bring the display case to the desired temperature. The high colour render index of the lighting contributes to the impressive experience of the masterpiece in the religious context of the cathedral. An innovative passive temperature and humidity buffering system has been installed in the display case, which also dampens climate fluctuations in the case of failure of the active climate system.