Research into preliminary sketches

An initial useful application of the technique is research into preliminary sketches. IRR makes it possible to look underneath the coats of paint at the initial drawing which the painter made before applying the paint.

Infrared light is largely invisible for the human eye and penetrates more deeply through some materials than ordinary light. The rays go through the coats of paint on the painting and are reflected by a primer. A special camera detects those reflected rays, since they are white on the image, the so called ‘infrared reflectogram’. Materials which contain carbon, such as pencil or charcoal, absorb infrared rays. Those zones are therefore darker on the ‘infrared reflectogram’.

Most painters from the 15th and 16th centuries made preliminary sketches on a panel or canvas prepared with a white primer. Therefore, works from that period can often be well researched using infrared reflectography.

The results can give an impression on how the artist set about the work. For instance, you can see what the artist’s drawing style looked like, whether he or she applied changes or corrections, or whether he or she used auxiliaries such as perspective lines or stencils.

Insight into the coats of paint

Infrared reflectography also gives information about coats of paint. Indeed, various pigments or types of paint react differently to infrared rays by absorbing or reflecting them to a greater or lesser degree. This method often also reveals restored zones clearly.

Aim of the research

The technique is deployed within the research centre to examine its own collection in preparation for an exhibition or a restoration, but also for systematic documentation.

Moreover, the acquired knowledge is made available to national and international partners. On the one hand, the Flemish Research Centre for the arts in the Burgundian Netherlands conducts research for external parties or it facilitates external researchers within Musea Brugge. On the other hand, it contributes actively to external art history research projects, such as, for instance, the VERONA project of the Royal Institute for Cultural Heritage (KIK-IRPA).