36 
MuseoMag   N°I 2025 
UNVEILING HIDDEN STORIES 
Scientific imaging reveals Jan De Bray’s artistic process 
Removing Jan De Bray’s Portrait of Andries Van Hoorn from its frame. 
© 
éric 
chenal 
One of our most fascinating jobs is the technical 
study of artworks, which can be defined as the 
physical understanding of the object. For example, a 
painting is traditionally made up of different layers; 
the support, a ground layer, an under drawing and 
the final paint layer. By examining this structure, 
we analyse the materials and techniques used to 
create these masterpieces. To access the different 
layers, we use non-destructive techniques, which 
include scientific imaging like photography in 
normal light, ultraviolet light (UV) and infrared light 
(IR). This meticulous study not only enriches our 
understanding of cultural heritage, but also provides 
valuable insights into the art-making processes of 
different time periods. 
When the Portrait of Andries Van Hoorn, by Dutch 
17th 
century painter Jan De Bray (1627-1697), arrived 
at our restoration studio, it underwent this imaging 
protocol. The findings from the infrared photographs 
were particularly revealing, offering a fascinating 
glimpse into the artist’s creative process. IR can 
detect underdrawings and other primary stages 
(the initial drawn or painted composition on the 
canvas), which are often masked by the painted 
surface. What secrets lie in the depths of this 
portrait? Join us as we delve deeper into this 
imaging technique and uncover the hidden stories it 
tells about the artwork’s creation. 
A CAPTIVATING DIVE 
Infrared light allows us to dive into materials. At 
a longer wavelength than visible light, it passes 
through paint layers until it is absorbed or reflected 
back. In practice, this technique involves pointing 
an IR light source at the painting’s front. The light is 
then absorbed by certain materials like carbon- 
based substances, often used as drawing media. A 
specialised camera captures the contrast between 
reflected and absorbed light, revealing the under- 
lying drawings. As this method did not help us 
detect any underdrawing in the Portrait of Andries 
Van Hoorn, we then used a complementary tech- 
nique called transmitted infrared photography.