Notice the distinctly different layers in this cross-section of a painting under visible OM.The layers that comprised the pictorial film can be distinguished from the varnish, the underdrawing, and the ground layer.What might this tell you about the painting’s history?Cross-sections have traditionally been prepared by hand.A scanning electron microscope is also used to collect a so-called backscattered electron image of a cross-section.This image shows differences in elemental composition: areas with high average atomic number (such as the lead-containing ground layer) appear light in the images, whereas areas with low average atomic number (such as the organic layers surrounding the bright red layer) appear dark. You can see that Degas reworked this painting many times, because the composition differs between the two images.While microscopy is more invasive than photography or radiography, once a sample of the painting is embedded in a resin it can be analyzed with a number of instruments.
This fragment is mounted and the layers are exposed through sanding and polishing.Find out how many times Degas rearranged the composition of this painting. Next, look at the OM cross-section of the painting on the top right. Now that you know how many layers of paint he used, you can further explore the painting through an SEM back scattering image of the same cross-section (bottom right), where you will learn about the actual pigments that he used.Examine this Edgar Degas painting, The Milliners (top left), using 3 different types of technology. Experts know that Degas rearranged compositions and reworked paintings, but how could they prove it?An optical microscope makes fast analysis of surfaces possible.
In order to obtain information about the composition of the individual pigment layers in a cross-section, the samples may be analyzed with a scanning electron microscope.
Myth or fact: Impressionists – especially Monet – painted quickly, freely, and intuitively.