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A blank canvas

Imagine a miraculous plant, which produces two important materials that are found in the Girl with a Pearl Earring. The fibres that made the canvas and the oil that binds the paint both came from the same plant: flax.

Flax plant, illustration from Frans Eugen Köhler (1897) Köhler’s Medizinal-Pflanzen. Source: Wikipedia

In Vermeer’s time, cities around the Netherlands – especially Leiden, Haarlem and Amsterdam – were important centres for weaving and trading fabrics. Some flax was produced in the Holland, but most was imported from other parts of Europe, where it was cultivated for both its seeds and fibres. Linseeds were pressed to produce oil, which could be used to make oil paint (something I’ll talk about in a later blog entry). Flax fibres were taken from the skin of the plant stem. The coarse flax fibres were used to make rope and twine, while the longer ones were spun to make fine threads. These threads were woven on a loom to produce canvas fabric, which would then be sold as pieces, bolts, or rolls. Recent research by the Counting Vermeer project found that several pairs of Vermeer’s paintings came from the same roll of canvas, but unfortunately, the Girl with a Pearl Earring hasn’t yet found a ‘roll-mate’. Perhaps, in someone’s attic, there lies an undiscovered masterpiece.

X-ray by René Gerritsen

The canvas that Vermeer used as a painting support was made of linen, woven on a loom in a plain weave pattern: one thread over, one thread under. If you zoom into the x-ray of The Girl, you can see a very fine grid: the horizontal and vertical threads of the canvas. As part of the Girl in the Spotlight project, Rob Erdmann scanned the x-rays at high resolution and used computer-assisted thread-level canvas analysis to determine that the canvas has an average of 14.66 horizontal by 14.5 vertical threads per centimetre. The thread count of The Girl is consistent with other paintings by Vermeer.  The data from thread-level canvas analysis can also be visualised as two kinds of ‘maps’, for both the horizontal and vertical directions.  

Thread angle maps (horizontal and vertical). Computer-assisted canvas analysis: Rob Erdmann.

The thread spacing maps (fig. 7c) show how the density of the threads varies across the canvas. This means that when the number of threads per centimetre deviates from the average, it is given a specific colour. This creates a kind of ‘barcode’ pattern for the painting. As I mentioned earlier, this pattern of lines has helped match the canvas of pairs of Vermeer paintings that were cut from the same roll of fabric. 

Thread spacing maps (horizontal and vertical). Computer-assisted canvas analysis: Rob Erdmann.

The weave angle maps show deviations in the angle of the threads, for instance, if the threads have a curve or distortion. In both maps, there are ‘waves’ around the edges, which we call cusping. Cusps form at the points where the canvas was pulled to attach it to a wooden stretcher or strainer. Tomorrow, I’ll explain how the cusping around the edges of The Girl’s canvas came about.



  • X-rays made by: René Gerritsen Art & Research Photography (René Gerritsen Kunst en Onderzoeksfotografie)
  • Thread level canvas analysis and curtain viewer: Rob Erdmann, Senior Scientist at the Rijksmuseum and Professor of Conservation Science at the University of Amsterdam

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