Rembrandt Restoration Provides Impasto Insights


A team of researchers from global coatings company AkzoNobel has recently discovered several ways of creating the “perfect impasto” as part of a years-long analysis of Rembrandt’s 17th-century masterpiece, “The Night Watch.”

Researchers and conservators at the Rijksmuseum in Amsterdam have been working to learn more about the painting for several years as the teams prepare for its first restoration in over 40 years.

Project History

Akzo Nobel and the Rijksmuseum first announced a partnership and that they’d be working on the 377-year-old painting in July 2019. Previously, The Night Watch had been hidden in a bunker within coastal dunes at the start of the second world war. The painting reportedly remained there for four centuries before being rediscovered.

“The Rijksmuseum continually monitors the condition of The Night Watch, and we’ve discovered that changes are occurring, such as blanching on the figure of the dog in the lower right of the painting,” said General Director of the Rijksmuseum, Taco Dibbits, at the time.

“To gain a better understanding of its condition as a whole, the decision has been taken to conduct a thorough examination. So, we’re extremely grateful to AkzoNobel, as the work that’s being carried out with their support is vital.”

Working encased in a glass chamber (to keep the painting displayed for the museum), the team said that it would first take about 11,400 high-resolution photographs of the painting. Then, special scanners planned to look at cracks and crevices while a laser examined the pigments. The hope is that all the images would give workers what they needed to proceed.

At the time, AkzoNobel called the undertaking “the most innovative restoration in the history of art.”

The process seeks to answer questions such as: How was the painting made? What was the original appearance of the painting intended by Rembrandt? What is the current condition of The Night Watch? What type of paint alterations have taken place and why?

In February 2020, the team released an update on the project, revealing that they had identified three key areas to focus on as the collaboration starts to gather pace.

Scientists from both parties shared the following key areas as what they planned to focus on for the next two years:

  • Recreating Rembrandt’s impastos (the technique of laying on paint so thickly that it stands out from the surface) - Understanding how Rembrandt created his famous impastos will involve gaining a better insight into the relationship between rheology (the study of the flow of matter in a liquid state or as a soft solid) and practical paint-application behavior. Three different pigmented impasto paints found in Rembrandt’s work will be selected and investigated from different perspectives.
  • Designing custom color calibration – This is to improve the photograph and digitization of the paining, which has become common issue with professional photographs of The Night Watch and other 17th century Dutch paintings. These images tend to show a consistent brightening of dark areas in the artworks, which misrepresents those paintings on photographs in museum catalogs and other publications, the entities said.
  • Improving the viewing experience – To help enhance the viewing experience of the painting, the plan is to analyze hyperspectral and spectroradiometer data and use physics-based simulations to propose changes in the local lighting that could be used to improve the visibility of the painting.

“This is an incredible opportunity for us to contribute our color expertise to an historic project,” said AkzoNobel’s Senior Color Scientist, Eric Kirchner. “The Night Watch is an iconic painting, not only in Dutch culture, but in the whole history of art. So being involved says a lot about us being the reference in the industry.”

What’s Happening Now

As outlined in previous years, AkzoNobel’s research and development manager Gerard van Ewijk has been determined to uncover the recipe used by Rembrandt in his “impasto” technique. The method, which has also been referred to as wall filler, involves layering paint thickly enough to stand out from the canvas.

The team recently discovered that the innovative, 3D effect used egg yolk in the mixture. Katrien Keune, head of science at the Rijksmuseum, shared that yolk was believed to have been mixed and boiled linseed oil and lead oxide to create a thick coating.

According to researchers from Sorbonne University in France, the tempura paint—also known as egg tempera—reigned as a supreme medium among Renaissance artists, such as Leonardo DaVinci, Raphael and Sandro Botticelli.

Before oil paints made their debut, the yolk-based paint was utilized for numerous murals in ancient China, Mycenaean Greece, Egypt and Babylonia for its durability, quick-drying properties and the ability to appear opaque and luminous.

To better understand the 15th-century coating’s molecular structure, researchers took to paint recipes recorded in a handbook called Il libro dell'arte by Italian painter Cennino Cennini, according to a French National Center for Scientific Research statement.

In the research currently underway, however, Van Ewijk pointed out that there had not been any need for the egg yolk in order to create the same effect. To that end, he shared that the 30:70 ratio of raw linseed oil and lead white creates the perfect impasto paint, offering a plausible alternative recipe to what was previously assumed to be used.

“We even questioned whether the previous analysis had been correct but we think the egg was definitely there,” Van Ewijk said. “There are multiple recipes he could have used … I think one of the outcomes is that you don’t actually need [the egg] so it is still a bit of a mystery why it is there.”

While the discovery seemed to create more questions about paint techniques rather than answers, the team of researchers also noted that they had recently delivered advances in the creation of Polycell, Dulux’s brand of wall filler sold in the United Kingdom.

“Looking at how he got such structured paint is helping us understand wall filler in a slightly different way,” Van Ewijk said, citing the new techniques used by his laboratory to examine their efforts at replicating the impasto.

As the team prepares to begin the official restoration process, they’ve shared that the first step will involve correcting a deformation in the top left-hand corner of the canvas. The damage is thought to have occurred while being housed in the Philips wing of the Rijksmuseum during the main building’s renovation between 2003 and 2013.

To prepare for these corrections, the 3.63-meter (11.91 foot) by 4.37-meter painting was removed from its 1975-era wooden stretcher and fitted to a new, non-reactive material frame.

Next steps regarding the painting’s restoration are expected to be announced in December.


Tagged categories: AkzoNobel; Asia Pacific; Coating Materials - Commercial; Coatings technology; Decorative painting; EMEA (Europe, Middle East and Africa); Fillers & surfacers; Good Technical Practice; Latin America; Maintenance + Renovation; Maintenance coating work; Museums; Museums; North America; Projects - Commercial; Research; Research and development; Restoration; Restoration; Z-Continents

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