Glistening “diamonds” in The sower, grains of sand in The sea at Les Saintes-Maries-de-la-Mer, a new shade of blue that refused to catch on, recycled canvases and an insight into the artist’s social networks… With their broad sweep, our investigations have brought us a little closer to understanding what drove Van Gogh and how he worked. For example, contrary to what many people think, it seems that he did not work in complete isolation. And he employed quite standard techniques to master his craft. Our research has also answered questions about the materials he used, the shops where he bought his supplies, his workplaces – both indoors and out – the other artists he was friends with and the theories he was aware of. The result is a valuable all-round picture of Vincent van Gogh the artist, and one peppered with surprising new insights.

The research phase of the project is now at an end. Over the next few months we will be bringing together all our findings and tying up the loose ends. Behind the scenes we are already compiling new publications and working hard on preparations for the 2013 exhibition. As well as works by Van Gogh from the museum’s own collection, this will include many items loaned for the occasion. For visitors it will be like stepping inside a laboratory equipped for all the latest state-of-the-art research techniques, which they can actually observe and experience. Who knows what might still be discovered there…

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 We have already touched on the topic of complementary colours a few times on this website. But just what makes this complementary effect so special? Underlying this phenomenon is a physiological explanation. The optic nerve that translates incoming information into shapes and colours has a very distinctive property that helps it to process colour. Each colour that falls upon the retina is perceived as if it were an attack that must be weakened. The eye does this by instantly creating a matching filter in a complementary colour in order to protect the optic nerve from irritation. This filter in a complementary colour acts to somewhat neutralise the original colour.  Try the following experiment on a sunny day. Take a large sheet of clean white paper, and paint a bright red dot on it. Hold the paper in the sunlight and stare closely at the red dot for 20 seconds. If you then close your eyes, you will see an after-image of the dot; instead of red, however, it will be green, which is the complementary colour of red. The reverse is also true – a bright green dot will produce a red after-image. If you take one of the other two primary colours – blue or yellow – the after-image formed will be in their respective complementary colours, orange and violet. 

You may be asking yourself  ‘So what?’ Yet painters who understand this phenomenon, and take it into consideration in the colour composition of their paintings, can achieve interesting effects. The previously mentioned physiological phenomenon means that complementary colours have a strong effect on each other: a splash of orange on a blue plane reinforces both colours. A patch of green against a red background produces a brighter contrast than it would against a brown background. Take a good look at Van Gogh’s paintings, especially those from his time in the south of France, such as Self-Portrait with Bandaged Ear. The background in this self-portrait is made up of two main colours: orange and red. These form a powerful contrast to their complementary colours blue, used in the hat, and the green of the overcoat. This was a deliberate choice of colours by Van Gogh, as we know that the walls in his studio in Arles were white. 

Vincent van Gogh, Self-Portrait with Bandaged Ear, 1889 (private collection)

This use of contrast can also be more subtle and varied, as in pointillist paintings, a technique Van Gogh experimented with during his time in Paris. Pointillism works because when we look at a painting, we do not keep our eyes tightly fixed on one point.  Instead, our eyes roam across the image absorbing what we see, and this brings our optic nerve in a constant state of confusion. It has to continually adapt and change the filter in an instant. This produces an interesting effect that is particularly heightened in pointillist paintings, a kind of optical vibrato without actual movement. Take Van Gogh’s painting Bank of the Seine, painted in the summer of 1887, a fine example of his experimentation with painting using stippling, which in his case would evolve into a technique using stripes. In this work small dots of red light up against the green planes of the leaves, pink hues are used near to soft shades of green, stripes of orange in varying degrees of brightness have been placed alongside blue ones and so on. Every square centimetre is a symphony of colours. 

Vincent van Gogh, Bank of the Seine (detail), 1887, Van Gogh Museum, Amsterdam

This technique has many more practical applications that can be used to good effect. If, for example, a single colour – orange – is predominant in a painting of a field of wheat, then grey stripes of shadow among the wheat will be perceived as blue-violet, even if the painter has used a neutral shade of grey. This is because the optic nerve activates its blue-violet filter to compensate for the orange-yellow colour, and the grey is then seen through that filter. This is known as simultaneous contrast. So a painter who has a good understanding of this process and uses it to his advantage in choosing the colours for shadow areas can produce brilliant effects. 

Pointillists tend to work with large planes, and are able to use complementary colours and simultaneous contrast to create very interesting colour perceptions, such as a fascinating tone of grey emerging from a plane filled with carefully positioned orange and blue dots. To really see this effect at work, start by looking at the painting from a distance, and see how it changes as you get closer. 

There is much more that can be said about these physiological effects on the eye and the publications on this subject by Johannes Itten (1888-1967), artist and teacher, make fascinating reading.  Wikipedia also lists interesting links to information on different types of colour contrast. 

By Rob Bouwman and Teio Meedendorp

Vincent van Gogh, Nude girl, seated, 1886, Van Gogh Museum, Amsterdam (Vincent van Gogh Foundation)

X-ray photograph of the painting Nude girl, seated, showing the underlying flower still life. The red lines were added.

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My research associate Teio thought it might be possible to date the work more accurately if we found out what kinds of flowers Van Gogh had painted. In the X-ray photo, the flowers appear to be bunched into racemes. They could be hyacinths, but lilacs are also a possibility. Lilacs bloom from late April to early June, while hyacinths flower from April to mid-May or even as early as January in a pot indoors. If these flowers are hyacinths, then Van Gogh could conceivably have made this painting in Antwerp, before moving to Paris. Yet that seems improbable, because the type of canvas that he used is associated with his Paris period.

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For several weeks, the painting visited our laboratory at the Cultural Heritage Agency of the Netherlands. During that time, the XRF scanner was used to measure the elements present in the paint. We scanned not only the uppermost paint layer, point by point, but also the layers of the flower still life below. This involved irradiating the paint with X-rays. In response, each element produced characteristic radiation. This showed me what elements are present, allowing me to deduce what pigments must have been used in each paint layer.

As fascinating as this may sound, the actual scanning is quite boring! The scanner took a week to cover a few dozen square centimetres of the paint surface. At least twice a day, I would stop by to check whether it was stuck. I made a back-up every day, because if the computer crashed, I certainly didn’t want to lose the results of the scan.

The XRF scanner measuring the elements present in the paint.

Checking the XRF scanner

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The scan for the element mercury revealed that the red pigment vermilion was used for the flowers. With a microscope, we had previously found traces of violet on the paint surface. This colour probably consists of ultramarine blue (which cannot be detected by an XRF scan) mixed with red (specifically, vermillion).

The scan did not provide a definite answer as to the type of flower depicted, since both hyacinths and lilacs can be violet in colour. It did give us a much clearer image of the concealed painting, however, along with a wealth of new data that will help us to answer other research questions in future.

XRF scan of copper and arsenic in the underlying flower still life

Reconstruction of the colours of the flowers in the underlying still life

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But Teio suggested that if we took a closer look at the X-ray, we might be better able to date the concealed picture, and therefore the painting of the nude girl as well. The bunched flowers are clearly emerging from the top of a tall vase. This is a more natural place for lilacs than for hyacinths, which are normally attached to a bulb planted in a pot. If these are lilacs, then Van Gogh could have painted the flower still life in the second half of April and then painted the nude girl over it in mid or late May, fairly soon after the flower painting was reasonably dry and just before leaving the Atelier Cormon.

This is exactly the kind of thing that makes my job so exciting! My area of expertise is materials research and technical examination of art, but as a chemist I have a different way of thinking from Teio’s. Through discussion, we can refine our research questions and come up with ideas for further investigation.

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You can find more information about this painting and other re-used Van Gogh canvases in the Van Gogh Museum, where the display Van Gogh’s studio practice: Canvases re-used will be on show until June 2012.

In May 1889 Van Gogh was admitted to an asylum for the mentally ill in Saint-Rémy-de-Provence, not far from Arles. He would remain there for a year. In addition to the standard cell assigned to every patient, he was allowed to use another one as a studio. There was plenty of room: about thirty cells were unoccupied.

Unlike his fellow patients, Van Gogh was allowed to continue working as usual, both inside and outside the institution. He felt it was essential to his recovery, and the physician handling his case agreed. In any case, it took his mind off his troubles.

Aerial view of the asylum Saint-Paul-de-Mausole, near Saint-Rémy-de-Provence. A: the men's wing, with an arrow marking Van Gogh's cell; B. the north wing, where Van Gogh had his studio. Both wings had views of the large, overgrown garden with pine trees, another place where Van Gogh liked to work.

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Bars

All the rooms in the asylum were barred, including Van Gogh’s studio. It is hard to imagine a sharper contrast with the studio in Arles that he had just had to leave, his beloved Yellow House. On the other hand, he had often had improvised working spaces in the past, and at least in Saint-Rémy he had a view of a lovely, overgrown garden. It was the only one of his studios of which he made an interior study, in which the bars outside the window are clearly visible.

Vincent van Gogh, Window in the studio, Van Gogh Museum, Amsterdam (Vincent van Gogh Foundation)

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Location

Although we know that Van Gogh’s studio was in the north wing, we do not know the exact cell. And although we assume that it was on the first floor (the upper level), a remark in a letter suggests otherwise. In the autumn of 1889, when Vincent wanted to send his brother Theo some paintings, he wrote that his work was ‘drying very badly because of the dampness of the studio. Here the houses have scarcely any cellar or foundations, and one feels the damp more than in the north’ . This probably was true mainly on the ground floor.

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Spectators

The asylum housed a wide variety of patients. Some had only minor problems – Van Gogh himself mostly fell into this category – while others were severely ill and could cause serious disturbances. Van Gogh described such people with compassion: ‘They all come to see when I’m working in the garden, and I can assure you are more discreet and more polite to leave me in peace than, for example, the good citizens of Arles’ . The people of Arles who had driven him out of the Yellow House and complained to the police that he was a dangerous madman who should not be allowed to roam free.

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Attacks

During his stay in Saint-Rémy, Van Gogh had a number of severe attacks, all of which took place outside the asylum. After each attack, he returned to working exclusively in his studio for a while before he dared or was allowed to go outside again. Most of the attacks were short and intense, but the last one, which began in late February 1890, lasted almost two months before he finally felt better. While recovering his strength, he was allowed to work in his studio, and he produced a few small paintings based on drawings and memories: landscapes with farmers and huts, which he described as ‘reminiscences of the north’.  In the meantime, Theo had found a place for him in the northern French village of Auvers-sur-Oise on the outskirts of Paris, where Vincent moved in May 1890.

Vincent van Gogh, Recollection of Brabant, 1890, Van Gogh Museum, Amsterdam (Vincent van Gogh Foundation)

A shop selling artists’ supplies in Montmartre was the setting for a similar encounter in 1887. Vincent van Gogh bought his canvas from the roll there, as did many other leading artists. But we could never find out who it was who came into the shop before him or after him.

Until now, that is: in an extraordinary research project the fabrics of artists’ canvases have been meticulously compared. This has revealed canvases from the same roll and it has emerged that the young artist Émile Bernard worked with exactly the same canvas as Van Gogh during the few months he spent in Paris. The two resulting paintings are now linked together for eternity – the perfect match.

Counting the threads 

Simply put, the computer is able to precisely count the number of threads that run near-vertically and horizontally across each square centimetre of a painting canvas. Usually the automated thread counting is performed on a digital X-ray image, which reveals the canvas weave structure of a painting.

Detail of an x-ray of a painting revealing the canvas weave structure, with overlaid counting grid.

Weave maps

Slight fluctuations in the spacing of the threads across a piece of canvas emerge, a natural consequence of the weaving process. These variations appear as colour-coded stripes in ‘weave maps’, forming a distinctive pattern for each canvas. When the pattern of stripes in the weave map of one painting exactly aligns with the pattern of stripes in the weave map of another painting, we can conclude a ‘weave match’ i.e. that the two canvases were cut in alignment from the same piece of woven cloth.

A match

We were quite excited when the computer turned up a weave match between two pictures painted in Paris in 1887, one by Van Gogh and the other by Emile Bernard, his younger friend and colleague in the period.

Reconstruction of how the two painting canvases were cut from the roll. Emile Bernard’s Portrait of his Grandmother was turned 90˚ in alignment with Vincent van Gogh’s Plaster cast of a woman’s torso.

Weave map illustrating a match in the pattern of warp threads running through both canvases down the length of the roll.

An intimate link

It appeared that the canvases used by both painters had been cut from a single piece, not by the painters themselves, but by a commercial manufacturer. The reverse of both pictures is now covered up by an added support canvas. Yet a figure ‘6’ stamped onto the back of  the original canvas used for Plaster cast of a woman’s torso shines through the backing canvas. This confirms that the canvas was commercially prepared and sold ready-stretched on a standard-sized frame, in this case corresponding to a Landscape 6 size ( 41 x 27 cm).

So it is likely that Van Gogh and Bernard visited the same artist supplies shop in Montmartre to purchase their ready-made canvases. Surely one cannot imagine a more intimate link between the practice of two painters than a shared shopping venue.

Not having enough (affordable) models, Vincent van Gogh also used to portray himself in various different poses. As an artist in one painting, and a well-dressed middle-class dandy in another, or a serious man-with-pipe. Or as a free-and-easy country lad wearing a straw hat. Funnily enough he did some of the sketches for these portraits on the backs of other paintings. That saved money for new canvases and meant he could keep both sides, as opposed to when he used to paint over an existing work.

This enabled him to maintain a high production rate during his labour-intensive Paris period. Despite their sketchy nature, the portraits were certainly not without merit. After all, the best ideas are conceived on the back of a beer mat… or on the back of a painting.

Ella Hendriks, Senior Conservator at the Van Gogh Museum,  closes in to focus on five self-portraits made on the backs of paintings  from the Nuenen period.

When artists in the past visited Drenthe to gather inspiration, they used to single out the wild northern part of the province. However, in the autumn of 1883, Van Gogh found himself among the southern peat moors instead. These wet, sodden fenland areas have little to offer that is of interest, apart from peat that is. And during his stay, from September to December, we can safely assume that the weather was not always fair.

In this early stage of his career as an artist – he had just seriously taken up painting in addition to drawing – he experimented with effects of light and darkness. Through his painting of a ploughed field in Drenthe, Van Gogh tells us a story, which researchers at the Van Gogh Museum were able to reconstruct. He played around with the composition and the figures in the picture, but was able to hide his preparatory work effectively. And so you see, there is more going on in the peat bogs than you might think.

Spot the differences.