The back of the panel
(reversed)
hold information. Here, the bevels
on the right and lower edges look fresh
compared to the top one. This indicates
that the portrait was cut down
at the right as well as at the bottom.
This X-radiograph shows a single dowel in the top part of the join between the boards. A second dowel must have been removed when the panel was cut down. The join shows up as a light area in the X-radiograph because the boards had come apart, probably when the panel was cut down, and were glued together using an adhesive mixed with lead white. Damage at the lower edge might have been the reason for cropping the panel; the X-radiograph reveals an old repair in the lower left corner.
Visible Ultraviolet Infrared X-ray Verso