The Girl must have been young when Vermeer painted her, but just as people develop wrinkles as they get older, paintings start to show their age in the form of cracks. The network of cracks that forms on a painting over time is also known as ‘craquelure’. It can be seen as a desirable part of the ageing process: a sign that the Girl has been around for more than 350 years.
Ground-breaking research
Cracks aren’t something that conservators spend much time studying as part of a typical treatment, but the ones in the Girl were of interest to the team who restored her in 1994. Jørgen Wadum, one of the conservators, made a diagram of the different types of cracks in the Girl, and what might have caused them:
- Strong pattern of age cracks,
- Spider web pattern, caused by pressure or sudden impact,
- In the corners: when the keys in the corner of the stretcher were tapped too hard,
- Fine cracks in the ground layer, formed soon after the ground was applied.
The 1994 researchers wondered why the cracks were so wide and dark in the Girl’s face. Some of it was caused by previous restoration treatments that were supposed to help the cracking, but sometimes did more harm than good.
The 1882 restoration probably used a water-based lining adhesive that made the original canvas shrink. This caused cupping in the paint and ground, and some paint losses. When the painting was restored again in 1915, the varnish was ‘regenerated’ with materials that might have caused further harm, including a tree resin called copaiba balsam. This was detected when the 1994 researchers analysed black material in the cracks.
A new look at the cracks
During the recent Girl in the Spotlight examination, our scientific instruments revealed different aspects of the cracks. A raking light photo (see above) shows the 3-dimensional relief of the painting, including the craquelure and slight cupping of the paint.
If tiny pieces of paint and ground become detached from the canvas, fragments flake off, leaving paint losses. On the x-ray, these appear black. The losses aren’t visible to the naked eye because they were carefully filled and retouched during the 1994 treatment. (As I mentioned in the blog about conservation history, some of the detached fragments got stuck in the varnish, and were saved as paint samples.)
Colour/topography
The Colour/Topography scanner used by Mathijs van Hengstum from TU Delft collects information about the crack pattern at a microscopic level in ultra-high resolution. A projector projects fine vertical and horizontal lines onto the painting, which are captured by two cameras positioned on either side. The deviations in the lines are translated by a computer into topographical information about the painting. The Colour/Gloss/Topography scanner used by Willemijn Elkhuizen from TU Delft detects differences in gloss., as well as the colour and topography. This is especially relevant in the background of the Girl. We know that originally this background was a dark greenish-black, but the colour and gloss have changed over time, making it look greyish and patchy. The Hirox hybrid 3d digital microscope captures images of the 3D surface of the painting. The cracks are visible as peaks and valleys.
