Investigation
Under Ultra Violet (UV) radiation:
UV radiation would show up any additions that were not original to the work. Paint pigments affixed during the same period would emit the same fluorescence under UV. In this case, the signature was genuine in that it did not have a different fluorescence.
Under Infrared radiation (IR) radiation:
IR can tell us about the technique used by the artist. Under IR radiation, preliminary sketches done in pencil or charcoal were detected.
1. Notice the wavy lines under the face of the gentleman. Conservators believe that the artist could have started sketching something very different before deciding to paint the portrait over it.
2. Irregular short lines were found around the eyes, nose and ear. These could have been guidelines for the artist to define the areas of shading on the cheeks.
3. Notice the brushstrokes on the background under UV. It looks as though the artist had applied paint freely onto the canvas.
