From the museum website
Two paintings by Jan Cornelisz Vermeyen (approx. 1500-1559) were recently restored and subjected to an intensive examination in the Frans Hals Museum. These were Cardinal Érard de la Marck (owned by the Rijksmuseum in Amsterdam) and The Holy Family (owned by Instituut Collectie Nederland, a Dutch heritage organisation, on loan to the Frans Hals Museum since 1948).
For some time it had been thought that these two paintings once formed a pair or even a diptych. This is suggested by the matching composition of the two paintings. For instance, the angel in the top right corner of the portrait of the cardinal points to the Holy Family in the other painting, and both panels are illuminated from the same source in the middle. In addition the green drape in The Holy Family is continued in the background of the cardinal’s portrait.
The restoration uncovered much of the original layer of paint used by Vermeyen. A visual analysis and a technical study of the paintings produced new arguments to support the hypothesis that the two currently separated panels once formed a pair.
Unfortunately there is no firm evidence, but the suggestion is so strong that it has now been decided to display the paintings together from now on.
This presentation describes the art historical and technical research as well as the practical aspects of the restoration.
Maastricht, Bonnefantenmuseum, exhibition Érard de la Marck en de Heilige Familie: twee panelen, een tweeluik? Onderzoek en restauratie van twee schilderijen van Jan Cornelisz. Vermeyen (Érard de la Marck and the Holy Family: two panels, a diptych? Research into and restoration of two paintings by Jan Cornelisz. Vermeyen) 27 January-30 May 2008)