Conservator, Michael Duffy: Even in a simple graphic image such as this, he's using a variety of painting techniques and methods. The white that forms the highlight on the white of the eye is in zinc. So it's a cooler white than the lead white used in the clouds, which are softer and warmer. And we can actually distinguish these in x-ray images that we have of the painting, where you can see the different densities of the paints.
Before cleaning, the pupil was very shiny and glossy and reflective. Once the varnish was removed, the black became very soft and deep. So it really does become the focus of the painting. You could also see more details in the clouds and the sky. Also, details, like the highlights in the corner of the eye, became much more apparent and visceral.