Technique and condition
The image is octagonal in shape; the spandrels at each corner, normally hidden by the frame, are painted brick-red. Although this paint does not extend beneath the whole painting, it is evident with microscopic inspection that it was applied before the composion was begun. No underdrawing or underpainting is visible with surface microscopy but a cross-section from the blue drapery shows a thin but opaque pale bluish grey underlayer. The main pigment in this drapery is Prussian blue, which occurs also in the sky, along with vermilion, a red organic pigment, ivory or bone black and lead white. Examination of the edges normally covered by the frame shows that the blue has faded slightly in the sky and sea. The yellow drapery contains mixtures of yellow ochres with Naples yellow and lead white.
Tests with heat on microscopic samples indicated that the binding medium in the paint is unmodified oil. Despite this or perhaps because of the final 'fat' ground layer, the painting has developed a network of fine shrinkage cracks, which have been retouched. The canvas has a glue lining, which is probably of early twentieth-century origin. The varnish and restoration are more recent, though old enough for the varnish, which looks like dammar, to have yellowed slightly.