Vincent van Gogh’s Sunflowers (1889) is the most famous painting in the Van Gogh Museum in Amsterdam. In fact, the still life is so beloved by the public that it has been almost impossible to remove the painting from the gallery walls to conduct an in-depth study of it for decades.

But thanks to new, portable imaging technology, experts can now bring the research lab into the gallery. A crack team of conservators and art historians has been hard at work analyzing the painting in a landmark effort. And they are finally ready to present their findings in a special exhibition titled “Van Gogh and the Sunflowers,” which runs from June 21 to September 1. 

A team led by Ella Hendriks, a professor of conservation at the University of Amsterdam, has studied every inch of the museum’s painting using a combination of microsampling and non-invasive spectroscopic techniques, including ultra-violet, infrared, visible light, and X-ray technology. Hendriks likens the work to conducting a “full-body scan” on a human. The team has also compared the painting in Amsterdam to the Sunflowers the artist painted a year earlier, in 1888, which is now at London’s National Gallery. 

Here is a summary of the most consequential findings. 

1. Van Gogh’s Fingerprints

It is not unusual for odd things to turn up in Van Gogh’s paintings. A grasshopper was even found embedded in the surface of a landscape he painted en plein air. This time, conservators have uncovered two fingerprints on the middle of the top of Sunflowers, where Van Gogh added a wooden drip in order to extend the height of the canvas. Hendriks told artnet News this was added by the artist quite late in the painting process, after he must have decided that the flowers appeared too cramped at the top.

Although they are indistinct, the conservator says it is safe to assume the finger prints are those of the artist. “We have a whole collection of fingerprints of Van Gogh from around the edge of his paintings,” Hendriks said. “These ones are probably too indistinct to compare, but the wooden addition was original, so it would be logical to conclude that they are his fingers.”

Asked whether these prints might ever be useful for authenticating Van Gogh works, Hendriks conceded that it is “certainly a possibility.” There are some forensics specialists who are looking into fingerprint analysis as a method of art authentication—but this method has never been needed for works in the museum’s collection, she notes, as their authenticity is not in question.

2. A Surprise on the Back of Van Gogh’s Canvas

The back or verso of the canvas will be displayed publicly for the first time as part of the exhibition, showing where Van Gogh nailed a wooden strip to the top of the canvas to create more space for Sunflowers.

The verso of Sunflowers (1889). Image courtesy Van Gogh Museum, Amsterdam (Vincent van Gogh Foundation).

The back of the painting “tells us an awful lot,” Hendriks said. “It tells us about what has been done to the painting in the past. There were a lot of questions in particular about the history of restoration.”

3. The Painting Looks Very Different Today Than When It Was Made

When it comes to conservation today, “less is more,” Hendricks said. Restorers in the past were more invasive. There have been several ill-advised conservation procedures carried out on Sunflowers in its 130-year history.

It is known that the Dutch restorer Jan Cornelis Traas worked on the painting in 1927 and 1961, but little was known about what he did to it because he did not keep any records of his process. After reexamining the work with new technology, the team determined that the painting was coated in a layer of varnish in 1927, which was later removed. It was then varnished twice more in 1961. Varnishing 19th-century paintings would not be done today, but it was “very typical” in the 20th century, Hendriks explains.

A conservator looks at Vincent van Gogh’s Sunflowers (1889). Courtesy of the Van Gogh Museum. Copyright Maartje Strijbis.

The “dirty and yellowed” varnish, which also cemented some later retouches to the painting, could not be removed as it has fused with the paint in some areas. “We have to accept that [the varnish] belongs to the history of the painting now,” Hendriks said, adding that she oversaw a deliberately limited retouching where conservation was needed on top of the varnish.

Worse still, in the late 1990s, the painting was given a wax resin lining to secure the paint surface. This wax, which over time had turned slightly white, was removed during the recent conservation treatment.

These later interventions, combined with the aging of the materials used, have changed the overall color scheme of the painting, so it looks very different today to how Van Gogh originally intended. In addition to the warm tone created by the varnish, certain pigments, such as the red “geranium lake,” have grown darker, and others, like the “chrome yellow,” have faded. One of the conservators has created a partial, painted reconstruction of the Sunflowers, which will be included in the exhibition, to give visitors an idea of how the painting looked when it was originally created.

4. It’s More Than Just a Straightforward Copy

The new analysis of the painting has allowed the first detailed comparison of the Van Gogh Museum’s 1889 Sunflowers painting with the artist’s 1888 version, which is in London’s National Gallery. Both paintings have now been examined using the same techniques, allowing for a detailed one-to-one examination. And it turns out the the Van Gogh Museum’s later work is not just a straightforward copy of his 1888 canvas.

Ella Hendriks studying an X-Ray of Vincent van Gogh’s Sunflowers(1889). Courtesy Van Gogh Museum © Maartje Strijbis.

“Superficially they look quite similar, but there was actually a multitude of differences,” Hendriks explained. Changes to the artist’s palette hues and differences in the way the artist mixed the colors, as well as different brushstroke techniques, indicate that Van Gogh “was seeking to achieve something different, to improve himself,” she said. 

5. Why the Painting Is Too Fragile to Travel

A few months ago, the Van Gogh Museum announced a travel ban on its most famous painting. Hendriks says that it is a “preventative measure.” While the ground and paint layers are stable, the work is extremely sensitive to vibrations and fluctuations in temperature and relative humidity.

“Due to the wax resin lining that was ironed on, there are these small holes that go through the paint and canvas, so you want to avoid any risk of vibration,” Hendriks said. The effects of vibration are cumulative, so they even avoid moving the work a short distance within the museum.

While the conservator takes a “never-say-never approach” to the possibility of the painting traveling in the future, she says that however careful you are when moving an object, “there is always a minuscule risk of something happening, and you can never account for the unexpected.”

The Amsterdam exhibition will also feature 22 further sunflower-themed works, including Van Gogh’s The Yellow House (1888), and Paul Gauguin’s Vincent van Gogh Painting Sunflowers (1888), as well as a number of rarely seen drawings by the Dutch artist.

“Van Gogh and the Sunflowers” runs June 21 to September 1 at the Van Gogh Museum in Amsterdam.