Since this arrangement is typical for southern rather than northern Europe, the altarpiece was probably commissioned by a patron in Italy or Spain, where Netherlandish painting was extremely popular.
No master would have completed such a large commission alone.
Today, new scientific techniques, especially infrared reflectography, which makes it possible to see the underdrawing hidden beneath the paint, are helping to discern the participation of workshop assistants.
Here the basic composition in all three panels was drawn with sketchy parallel strokes, probably with charcoal or black chalk.
In the central panel only there is additional underdrawing in ink or paint.
This provides more detailed instructions and could indicate that David’s assistants, who would have needed more guidance than the master himself, were responsible for the center panel.
Presumably David painted much of the two wings himself.
Notice how the underdrawing shows through the folds in Anne’s robe as blue-gray hatching.
The focus exhibition (26 January - 10 May 1992) featured 3 panels and 6 smaller panels.
Also on view were photographs of hypothetical reconstructions of the panels, and infrared reflectography of the underdrawings of those in the NGA.
The panels of the triptych were restored prior to the exhibition by Cathy A. Metzger, conservator for the systematic catalogue, NGA.
The exhibition curator was John Hand, curator of northern Renaissance paintings at the NGA.