Unveiling Rembrandt's "The Night Watch"

© https://www.rijksmuseum.nl/en/press/press-releases/operation-night-watch-to-start-at-the-rijksmuseum

"Operation Night Watch" is the name of a huge research and conservation project that started in Amsterdam's Rijksmuseum on July 8, 2019. The goal of the project is to understand Rembrandt's painting process of his famous "The Night Watch" and apply the findings to the long-term preservation of this 17th century work of art.

This challenging project has taken Bruker's M6 JETSTREAM into a mobile working platform directly in front of the unframed painting. The painting and the instrument are surrounded by transparent walls, creating a glass laboratory in the Gallery of Honor and keeping the work of art available to the public during the analysis. A digital platform allows that not only the visitors on site, but viewers from all over the globe can follow online how the painting is being scanned millimeter by millimeter with an X-ray beam. The scans of the entire canvas reveal the chemical elements that Rembrandt used in his paints more than 375 years ago. Due to the enormous dimensions of the painting, 56 scans were needed. Each of the scan takes 24 hours.

Non-invasive Elemental Analysis

The M6 JETSTREAM is a micro X-ray fluorescence (Micro-XRF) spectrometer specially developed for the non-invasive on-site analysis of large format objects. The working principle is based on the detection of the fluorescence induced after irradiation of a sample with X-rays. Since this fluorescence radiation is element-specific, its analysis allows to determine the chemical composition of a sample. XRF is widely applied in the field of Art & Conservation, because it does not require sample taking and does not touch the valuable objects.

M6 JETSTREAM's innovative design enables the analysis of a huge painting such as Rembrandt's masterpiece "The Night Watch" directly at the exhibition place and minimizes therefore safety risks and costs associated to the transport of valuable paintings. The spectrometer integrates a unique measure head positioning kinematic, a polycapillary lens for focusing X-rays onto a small spot and high-performance detectors. The small spot size can be adapted in five steps without significant loss of excitation intensity to match the structure of the painting's surface and the desired spatial resolution.

Analysis of Pigment Distributions

During the analysis, the X-ray beam penetrates all layers of the painting, and the emitted from different depths of the painting is detected depending on its energy. For each element, two-dimensional element distribution maps are created. They detect compositional variations in the painting and help understand Rembrandt's working process, even revealing corrections made by the painter. It is already known today that Rembrandt lengthened lances or changed the positioning of figures in the picture.

The information on element composition and distribution is crucial for the multidisciplinary data evaluation. It helps art historians, conservation specialists and material scientists find answers to questions like what type of pigments were used, how they might have degraded and which changes were made during or after the painting was created.