The painting under infrared light

copehagen 1000px copenhagen ir

Infrared rays allow the conservators to see a painting’s underdrawing. This can reveal whether the composition has been changed during the working process and can help identify the artist behind the painting.

Unlike X-rays, infrared (IR) radiation has a long wavelength, which allows it to penetrate the paintings in a different ways. The IR rays penetrate the colour layers and make the underdrawing beneath them visible to conservators.

Undertegningen på maleriet, som ejes af museet.

Underdrawing from the Copenhagen painting.


What is an underdrawing?

An underdrawing can be said to be a painter’s handwriting. It shows signature traits of a painter’s style. Examining the underdrawing often makes it possible to link a painting to a particular style and a particular workshop. The 16th century was a time of large workshops where the master had many apprentices. The apprentices were taught their craft in the workshop. It was not unusual for apprentices to spend 10 years copying their master before they were allowed to create their own work. It was not, then, necessarily the master who did the underdrawings. Thus it can be difficult to link a specific work to a specific artist.

A culture of copying

In the 16th century it was very common for artists to copy motifs and subjects. The practice was prompted by the great demand for specific subjects; particularly those originally created by major artists such as Bosch and Bruegel. The two artists lived around the same time, but had separate workshops. Many of the artists that came after them copied their motifs and subjects.

Undertegningen på maleriet i privateje.

The underdrawing of the privately owned painting.


Which painting came first?

If you have several almost identical paintings you can often use the underdrawings to determine which of them was the first to be created. A loosely sketched underdrawing frequently indicates that the painting in question was the first, for here the artist gradually decided on the final outline of their painting. A more detailed, firmly executed underdrawing indicates that the artist already knew exactly where the various elements would be placed.

The underdrawing becomes visible under IR light

The underdrawing becomes visible when viewed through an infrared camera that captures the radiation reflected by the painting. However, the underdrawing must be executed in materials that reflect IR – such as charcoal or black chalk – and on a base that absorbs IR – such as a white ground – in order to be visible. If, for example, the ground is dark red the underdrawing will often remain invisible under IR light.

The underdrawings of the four paintings

All four paintings have underdrawings executed in black coal against a white ground. As a result the conservators were able to see the underdrawings clearly. The Copenhagen painting has a very loose and sketch-like underdrawing, while the privately owned painting has a very precise, almost caricature-like underdrawing. The conservators do not know who created the four paintings, but it was neither Bosch nor Bruegel: dating the wood shows that Bosch would have been dead and Bruegel very old at the time these paintings were created.

Changes to the composition

The underdrawing also reveals whether the artist made changes to the composition while working. The Gallery’s own painting saw only small adjustments along the way, but the painting from the Kadriorg Art Museum in Tallinn originally featured a pig that has been painted over.

Maleriets undertegning, hvor grisen stadig ses i sækken.

The painting’s underdrawing with the pig still visible in the sack.

The final painting, where a brown sack has been painted in to cover the pig.


Updated: 22.mar.2017
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