Unusual compound found in Rembrandt’s The Night Watch

An international team of scientists from the Rijksmuseum, the CNRS, the ESRF the European Synchrotron, the University of Amsterdam and the University of Antwerp, have discovered a rare lead compound (named lead formate) in Rembrandt’s masterpiece The Night Watch. This discovery, which is a first in the history of the scientific study of paintings, provides new insight into 17th-century painting technique and the conservation history of the masterpiece. The study is published in Angewandte Chemie – International edition.

The Night Watch, painted in 1642 and displayed today in the Rijksmuseum Amsterdam (The Netherlands), is one of Rembrandt’s most important masterpieces and largest work of art. In the framework of the 2019 Operation Night Watch, the largest research and conservation project ever undertaken for Rembrandt’s masterpiece, an international research team joined forces to study how the painting materials react chemically and with time.

The team of scientists combined multi-scale imaging methods in order to chemically study the materials used by Rembrandt in The Night Watch. A X-ray scanning instrument developed at the University of Antwerp (Belgium) was applied directly to the painting, while tiny fragments taken from the painting were studied with synchrotron micro X-ray probes, at the ESRF, the European Synchrotron (France), and PETRA-III facility (Germany). These two types of analyses revealed the presence of an unexpected organo-metallic compound: lead formates. This compound had never been detected before in historic paintings: “In paintings, lead formates have only been reported once in 2020, but in model paintings (mock-up, fresh paints). And there lies the surprise: not only do we discover lead formates, but we identify them in areas where there is no lead pigment, white, yellow. We think that probably they disappear fast, this is why they were not detected in old master paintings until now”, explains Victor Gonzalez, CNRS researcher at the Supramolecular and Macromolecular Photophysics and Photochemistry (PPSM) laboratory (CNRS/ENS Paris-Saclay) and first author of the paper.

Read more on the ESRF website

Image: The Night Watch, Rembrandt van Rijn, 1642

Credit: Rijskmuseum Amsterdam

Nanomaterial from the Middle Ages

To gild sculptures in the late Middle Ages, artists often applied ultra-thin gold foil supported by a silver base layer. For the first time, scientists at the Paul Scherrer Institute PSI have managed to produce nanoscale 3D images of this material, known as Zwischgold. The pictures show this was a highly sophisticated mediaeval production technique and demonstrate why restoring such precious gilded artefacts is so difficult.

The samples examined at the Swiss Light Source SLS using one of the most advanced microscopy methods were unusual even for the highly experienced PSI team: minute samples of materials taken from an altar and wooden statues originating from the fifteenth century. The altar is thought to have been made around 1420 in Southern Germany and stood for a long time in a mountain chapel on Alp Leiggern in the Swiss canton of Valais. Today it is on display at the Swiss National Museum (Landesmuseum Zürich). In the middle you can see Mary cradling Baby Jesus. The material sample was taken from a fold in the Virgin Mary’s robe. The tiny samples from the other two mediaeval structures were supplied by Basel Historical Museum.

The material was used to gild the sacred figures. It is not actually gold leaf, but a special double-sided foil of gold and silver where the gold can be ultra-thin because it is supported by the silver base. This material, known as Zwischgold (part-gold) was significantly cheaper than using pure gold leaf. “Although Zwischgold was frequently used in the Middle Ages, very little was known about this material up to now,” says PSI physicist Benjamin Watts: “So we wanted to investigate the samples using 3D technology which can visualise extremely fine details.” Although other microscopy techniques had been used previously to examine Zwischgold, they only provided a 2D cross-section through the material. In other words, it was only possible to view the surface of the cut segment, rather than looking inside the material.  The scientists were also worried that cutting through it may have changed the structure of the sample. The advanced microscopy imaging method used today, ptychographic tomography, provides a 3D image of Zwischgold’s exact composition for the first time.

Read more on the PSI website

Image: The altar examined is thought to have been made around 1420 in Southern Germany and for a long time stood in a mountain chapel on Alp Leiggern in the Swiss canton of Valais. Today it is on display at the Swiss National Museum (Landesmuseum Zürich).

Credit: Swiss National Museum, Landesmuseum Zürich

From conservator to researcher at the world’s brightest synchrotron

Light sources around the world are playing an increasingly important role in helping to uncover the past and protect historical objects for generations to come. Ida Fazlić is currently a PhD student at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. Her research is focusing on the use of metal catalysts that are used to speed up the drying reactions of historical and industrial paints. Ida’s project will provide valuable information to collaborator Rijksmuseum on the use or misuse of dryers throughout history and up to the current day. Also there effect on the stability and aesthetic of the painted objects.

Ida was attracted to this area of work through her valuable experience of working as a conservator and restorer at the national gallery of Bosnia and Herzegovina. This work led her to question the chemical and physical processes that caused the degradation of the painted layers that she was seeing on a daily basis. Ida decided to study the crucial and very important role of science and technology in conservation of cultural heritage objects. For Ida, the best thing about working at a light source is that, “You have endless opportunities of going as far in your research as you want to go and in any direction that you want to go because at any moment you have the world’s most powerful material investigation techniques at hand.”

Conservation boost for 500-year-old shipwreck

The ESRF has allowed scientists to discover nanoparticles that could lead to degradation in a 500-year-old shipwreck: the Mary Rose, an English warship.

Almost 40 years ago, a salvage operation brought to the surface the Mary Rose warship, which used to be Henry VIII’s favourite warship and sank in 1545. Throughout these years, scientists have been using conservation treatments to preserve it. Unfortunately, the remains of the ship are vulnerable to degradation after spending more than 400 years at the bottom of the sea, where harmful deposits collected inside the ship’s wooden hull.

A team of researchers, led by the University of Sheffield, has used ctPDF, an x-ray technique developed at the European Synchrotron Radiation Facility (ESRF) and Columbia University, to obtain vital information on the nanostructure of substances lodged within the ship’s wood and that could lead to the Mary Rose degrading. 

Researchers were previously unable to obtain information on the nature and structure of these deposits, as they are incredibly diverse and exist on such a small scale. The fragility of the remains also hindered efforts to find out more about the substances.

ctPDF has enabled researchers to identify the harmful deposits for the first time and in a non-destructive way. Serena Cussen, Chair in Functional Nanomaterials at the University of Sheffield and corresponding author of the publication, explains: “This project has brought together researchers from around the world to uncover the nature of potentially harmful deposits lodged within the wooden hull of the Mary Rose. These deposits, when exposed to air, can act to degrade the wood. By understanding their structure, we might understand better these degradation pathways, as well as develop treatments that target their removal”.

Read more on the ESRF website

Image: The hull of the Mary Rose

Credit: The Mary Rose Trust

Unravelling the history of 15th Century Chinese porcelains

Researchers from French and Spanish Institutions used the combination of two synchrotron light characterization techniques to study Chinese blue-and-white Ming porcelains. They were able to identify the firing temperature by determining the porcelain’s pigments and the reduction-oxidation media conditions during their production. The approach they used can also be applied on a broad range of modern and archaeological ceramics to elucidate their production technology.

Pottery is found at the majority of archaeological sites dating from the Neolithic period, when first human settings appear, onwards. Which makes it a major focus of study in archaeological science.  The study of style and production of ceramics is central to the historical reconstruction of a site, region and period.

More specifically, ceramic technological studies look to reconstruct the production technology of ceramics, by determining the selection and preparation of the raw materials, the formation of ceramics, treatment and decoration of the ware’s surface and the firing atmosphere. All of this is possible thanks to the scientific techniques available nowadays.

In a recent publication, researchers from French and Spanish Institutions used the combination of two synchrotron light characterization techniques to study Chinese blue-and-white Ming porcelains. These characteristic porcelains, whose production flourished around the 14th century, are decorated under the glaze with Cobalt-based blue pigments that provided their distinctive blue decorations and produced during a one-step firing at high temperatures.

They were able to identify the firing temperature by determining the porcelain’s pigments and the reduction-oxidation media conditions during their production. The approach they used can also be applied on a broad range of modern and archaeological ceramics to elucidate their production technology.

Read more on the ALBA website

Image: Porcelain Jar with cobalt blue under a transparent glaze (Jingdezhen ware). Mid-15th century

Credit: Metropolitan Museum of Art.

“Invisible ink” on antique Nile papyrus revealed by multiple methods

Researchers from the Egyptian Museum and Papyrus Collection, Berlin universities and Helmholtz-Zentrum Berlin studied a small piece of papyrus that was excavated on the island of Elephantine on the River Nile a little over 100 years ago.

The team used serval methods including non-destructive techniques at BESSY II. The researchers’ work, reported in the Journal of Cultural Heritage, blazes a trail for further analyses of the papyrus collection in Berlin.

The first thing that catches an archaeologist’s eye on the small piece of papyrus from Elephantine Island on the Nile is the apparently blank patch. Researchers from the Egyptian Museum, Berlin universities and Helmholtz-Zentrum Berlin have now used the synchrotron radiation from BESSY II to unveil its secret. This pushes the door wide open for analysing the giant Berlin papyrus collection and many more.

>Read more on the BESSY II at HZB website

Illustration: A team of researchers examined an ancient papyrus with a supposed empty spot. With the help of several methods, they discovered which signs once stood in this place and which ink was used.
Credit: © HZB

Diamond’s light illuminates our Anglo-Saxon heritage

Oakington is a small, village seven miles north-west of Cambridge. Archaeological finds in the area suggest that there may have been a settlement here in the Stone Age. In 1926, horticulturalist Alan Bloom was digging at his new nursery in Oakington when he uncovered three early Anglo-Saxon burials. In the 1990s, Cambridge County Council’s Archaeological Field Unit uncovered 24 more burials, which had been discovered during the construction of a children’s playground.
Wondering what else was hidden under the Fens, archaeologists from Oxford Archaeology East (then known as CAMARC) found 17 more burials in 2006/7. And in 2010/11, a further 27 burials were found in new trenches around the playground, including the remains of children, which are rare finds from this period. The most recent excavations were part of the ‘Bones without Barriers’ project, which encourages community communication and participation.