Exposure tests in Panel 3
The upper left corner before and after the removal of the non-original paint and varnish: the damaged areas along the edges of the panels become visible. However, a large part of the original paint under the newer coats of paint and varnish remains intact and appears in a radiant light blue. The lower half of the image was not painted over but a layer of varnish had been applied which has grayed. After the removal of the varnish the colorfulness also clearly improves. In the lower right-hand corner there is still yellowed varnish.