National Gallery of Canada

Varnish
Varnish is a solution of resin, which dries to form a transparent film or protective coating over the paint.

Challenge

As previously mentioned the varnish had become hazy and brown.The old varnish and later additions needed to be removed. It appears that the nineteen year old artist had, initially, intended a smaller work but expanded the image by unfolding more of the herringbone canvas, extending first the lower edge, then the left side and then the lower edge again.

There are other signs that the painting was not finished to the usual degree, such as the obvious pentimento head between the patrons at the top right.

Click the forward arrow to see the "before and after" effect of this restoration project.

Pentimento
The visible evidence of an alteration to a painting that suggests a change of mind or concealed mistake. Over time, the covering paint layer may become transparent, revealing the artist's first statement.

Christ's Robe
The purpose of the microscopic analysis is to document the materials and techniques used by the artist as well as to compare them with those of other paintings by the same artist or other artists of the same era.

Man's Robe
Notice the discoloured retouching of the old tear

Head Shadow
Notice that the head had been painted over.

Infra-red Photography

Infra-red radiation is similar to visible light, but is slightly too long in wavelength for the eye to see; however, it can be photographed. In conventional infra-red photography, an image is recorded using film in an ordinary camera.

An infra-red photograph shows layers just below the visible surface of a painting; pentimenti and underdrawings done in carbon black on a white ground show up particularly well.

Play the transition then click on the head area to see more detail.

Ultra-violet Fluorescence

This photographic technique uses special filters over the light source and the lens of the camera, allowing only ultra-violet rays to reach the painting. These excite the surface layer in a characteristic way, indicating the type of varnish, the extent of its discolouration due to aging and how it was applied.

Ultra-violet photography can also reveal later interferences with the varnish and paint layers.

X-Radiography

This is a form of radiation that passes through solid objects, but is obstructed to differing degrees by different materials. In an X-ray image (known as a radiograph) of a painting, areas of paint containing lead pigment will appear almost white, while areas containing lighter materials will appear an intermediate grey or dark.