Reflectography

Test images with new IRr camera

In the painting restoration studio at the Kröller Muller Museum, a new device for Near Infrared Reflectography was recently used to take the first test images in the Netherlands of a number of paintings. Measuring only 8 cm3, the XS Infrared camera (320 x 256 pixels) by Xenics is the smallest of its kind. It covers a wavelength range of 0.9 – 1.7 μm (with extension ring). The only other attributes needed to take reflectograms are a computer (laptop) and a halogen lamp.The paintings selected for the trial were already known to have hidden images beneath the upper, visible paint layer.


The painting The Mill (1854) by Paul Gabriël depicts calm water in the foreground.

With the naked eye however, a different shape is faintly discernible underneath the paint layer of the water. Test images using IRr showed for the first time that Gabriël initially painted a boat here, which he later painted over. On the boat are two men and two cows.

Left: the framed painting with the XS-infrared camera in front
Right: an infrared reflectogram, with the boat and the men and cows dimly visible in the centre foreground

Two overlapping infrared reflectograms of the foreground showing the over-painted scene. The boat that Gabriël painted over is clearly visible. Men with broad-rimmed hats are seen pushing the boat along using long sticks. On the boat are two cows with their horns to the right.

In the case of Still life in a closet - a painting by an unknown Belgian artist - the naked eye can see that the artist drew a grid before he started to paint. Such so-called ‘square grids’ served as a traditional aid in copying examples. The grid showed up even clearer on the infrared reflectogram. Further evidence of pre-studies also became visible, such as shadings and other details. It emerged that the entire still life was based on detailed preliminary sketches that were subsequently painted over without any alterations or ‘pentimento’.


Left: Still life in a closet (normal, symmetrically lit)
Right: infrared reflectogram

Details to illustrate:
Left: the candle left under centre
Right: infrared reflectogram of same candle with a vertical and horizontal gridline and shadings and shadow lines in background

Furthermore, IRr reveals that the work was painted in a different year than hitherto assumed. The first two sentences on the piece of paper remain indecipherable, except for the year 1558. Up till now, this still life was dated 1538.


Left: microscopic photo
Right: infrared reflectogram

The Infrared Reflectograms were made by Frans Dam, thermographer at EMAD B.V.and Piet van Riel of Xenics nv led by Luuk van der Loeff of the Kröller Muller Museum.