The curator, along with my colleagues
in the post-1800 department of this small but remarkable display we have on in room
46 of the National Gallery, bringing together two versions of Vincent van Gogh's most famous
work, the Sunflowers; our own version here in the National Gallery, which was acquired
in 1924 thanks to the benefaction of Samuel Courtauld, and the version from the van Gogh
Museum in Amsterdam itself, which has always descended in the artist's family and is one
of the glories of that museum. The bringing together of these two pictures commemorates
15 years of particularly close friendship between the National Gallery and the van Gogh
Museum, which has seen us exchange a picture a year. Sometimes a year is 18 months but
more or less a picture a year. One of our impressionist or post-impressionist pictures
travels to Amsterdam and enriches the context in which van Gogh is shown there and a single
van Gogh comes from Amsterdam to broaden our small, very fine but small collection of van
Gogh pictures. This has been, I think we will agree, mutually beneficial and it is certainly
a great pleasure to our audiences in both places and to commemorate it, really, and
also to commemorate several years of research on van Gogh's technique, which we will be
talking about this evening. It seemed a propitious way of doing so, to do something quite simple
to bring the two pictures together, hang them side by side and let them in a funny way speak
for themselves. We're about halfway through the run now. This display has been seen by
115,000 people and we can assume that as many more will see it by the time it ends. We thought
that it would be very worthwhile to talk about some of the issues raised by the conjunction
of these two pictures and to do so we've invited our friend Ella Hendricks, the head of conservation
at the van Gogh museum who's worked for many, many years on van Gogh and his technique to
talk with Ashok Roy, the director of collections here at the National Gallery and for many
years a head of our scientific department. And in both places research into van Gogh's
technique has been intense and both Ella and Ashok will have very interesting things to
say. I will start off by simply laying in the background of the making of the pictures
and I thought I would start with this wonderful 1889 self-portrait, the brilliant view...
the brilliant blue of his smock and the brilliant blue of the background. But as in everything
with van Gogh, not everything is as it seems, even with this picture. That's right, because in fact the background
colour would have been purple originally so you would have had a contrast between the
purple and the yellow and I'm told by colleagues at the National Gallery in Washington that
when the picture was taken out of its frame you could actually see residues of the purple
where it had been protected from light. So they've managed to make a digital reconstruction
of how the picture could have looked originally. Thank you. Yes, it's interesting to know.
Let me just, as I say, fill in the background. Early in '88 Vincent van Gogh comes down from
Paris to Arles in Provence, there to paint in the brilliant sunlight of the south, there
to paint in the Japanese manner as he said and there he hoped to invite artists to come
with him. Particularly to invite Paul Gauguin to come down from Normandy... from Brittany,
excuse me, where the two would work together in what he called the studio of the south.
So much of the spring and summer saw Vincent working at a very high level of creativity
and also writing to Gauguin, inviting him over and again to come and join him in this
small and ancient city. And he began to prepare a welcome for Gauguin
in Arles by renting a small house and painting it yellow, you see... hence it's always known
as the yellow house. You see it here in this famous painting from the van Gogh Museum and
it was there in the Autumn of 1888 the two artists would live, paint, discuss art endlessly.
There were two bedrooms for the artists, which, as was his wont, Vincent painted his own bedroom.
Here you see it here again in a picture from the van Gogh Museum. Simple, straightforward,
a rather oddly shaped room with Gauguin in the room right next door to him. At a certain
point in the summer of 1888 Vincent decided that he would decorate the room of the yellow
house that would be Gauguin's bedroom, that he would decorate it by painting a series
of sunflower images; big vases of sunflowers. Why did he turn to this motif of sunflowers?
I think one reason is that he had been painting them in Paris before the descent down south.
He had had a very good response to them. Gauguin in particular had admired them and what better
way, than to welcome him than by painting a motif that he knew Gauguin would appreciate?
But there's very much more to it than that in the sense that the sunflower is a, kind
of, natural symbol, a richly valent object in nature that has had acquired, attracted
to itself many meanings over time. Certainly in French politics it's had very
specific meanings. Louis IV was the sunflower and like the sunflower... Louis IV, excuse
me, was the Sun King and like the sunflower the people of France would observe his passage
through the sky just as the sunflower follows the sun. It was also a symbol of joy, of colour,
of the sun itself. It was a symbol indeed of the loyalty that van Gogh was professing
to Gauguin. Gauguin would be the leader in their experiments in new painting and like
a sunflower, in a sense, van Gogh would follow his lead. That did not entirely turn out to
be the case. And so he began to paint a series of sunflower paintings in August of 1888,
choosing two of them then to decorate the bedroom of Gauguin,
including the London painting that you see on the screen, signed in blue so prominently,
Vincent. This great vase, an earthenware pot, vase of these magnificent flowers and one
other painting now in the Neue Pinakothek in Munich. He also symbolised the relationship
of Gauguin and himself in works like the two chairs, which would at a certain point make
another very good pairing exhibition here and in Amsterdam. Vincent's chair, simple,
rush-seated, very plain, very direct. His pipe and tobacco lying on the cane seat. Gauguin's
chair rather like Gauguin's own personality, rather more baroque, rather more ornate, rather
more artificial. And indeed the illumination in the room is an artificial gaslight. So
the two pictures become, and it's a wonderful poetic metaphor, the two pictures become,
kind of, surrogate portraits of the two artists themselves and of their relationship in terms
of inanimate... in terms of inanimate objects. They... Gauguin arrived, they painted for
several weeks in the autumn of 1888 side by side. Things went badly or began to go badly,
more and more disagreements of their approach to art entered into what they were doing.
Also any time you're with someone seven days a week for weeks on end nerves can get rubbed.
I think that that is certainly part of it as well. And it ended badly with their fight
right at Christmas of 1888, a bitter fight. Gauguin later would say that van Gogh pulled
a knife but it's not clear that actually happened. But Gauguin stomped off back to Paris. Vincent
had a nervous breakdown. Most famous event of that moment, he cuts off his ear, presents
it to... or a portion of the ear lobe, presents it to a prostitute in the town, has a collapse,
is hospitalised but amazingly after he... or as he is in the process of recovery he
begins again to paint sunflower pictures and returns in January of 1889 to paint sunflowers,
to paint the sunflowers that you see on the right. Now, in Amsterdam there are no sunflowers
blooming in January, of course, and so the Amsterdam picture is a copy, if you want to
use the word, of the London picture, which remained in front of him. The word that Vincent
used was repetition or in French, repetition, which in French has that implication of a
rehearsal, of redoing something in order to make it different, to make it better. An actor
in rehearsal is an actor en repetition. And that sense of something that is not static
but that is changing, that is constantly being rethought, is part of the process involved
in these two pictures. So I will turn over to Ashok to tell you some of the issues raised.
Okay, thanks very much, Chris. Those of you who have actually seen the display will notice
that in addition to the pictures we have x-rays of the two paintings on one of the walls in
the exhibition room and the reason why we thought it would be interesting for you and
the rest of the public to see these x-ray images is that it's actually the first time
that these x-rays, which have existed for some time, have been brought together. Now,
Ella and I have been working on the technique of van Gogh in these two pictures for a number
of years, rather on and off in fact, but quite curiously although x-rays were made of each
painting, one in Amsterdam and one here, we hadn't thought, perhaps
wrongly, to bring them together to make a comparison. And the opportunity of showing
the two pictures together enabled that other conjunction of a technical document to take
place. Now, perhaps slightly surprisingly I'm going to begin to say a bit about x-rays
and what they tell you by looking first at Titian. And the reason for showing you these
images is to explain that x-rays are not always at all easy to interpret. And this is a famous
case where an x-ray has given us a great deal of head-scratching as to what it actually
means. Now, Titian's Nole me Tangere painted in the early years of the 16th century has
this x-ray and it's very confused in its upper portion but what had been noted a long time
ago is that it appears that Titian painted Christ in a completely different originally,
apparently walking away from the Magdalene. Now here are his legs apparently. Now, from
later studies we understood that in fact this is a complete artefact. These are not Christ's
legs at all. In fact, it's an artefact of the application of the ground layer on the
canvas and what these objects are in fact are just curving applications of dense ground,
which just happened to look like a pair of legs pointing in the other direction. So it's
a warning when one looks at x-rays in comparison with pictures to make sure that you really
understand what you're looking at. And this is another
case of something that's slightly puzzling. This is a canvas picture by one of the Le
Nain brothers, or presumed to be, a French 17th century painting family, and at the right
you see the x-ray of the picture, which barely shows anything of the surface painting. You
can just about see this elderly woman's headdress here but underneath in fact there's a portrait
painted under the portrait [?]. So because the materials used to create that portrait
are much denser to x-rays than the surface paint in the genre scene [?] you see the image
in the x-ray dominated by the under painting, in fact. So these are all warnings about interpretation.
Now, some x-rays are very clear and you could say give you an honest view of the way in
which a picture is painted and this one is one of those paintings, a picture by a Roman
artist called Sassoferrato. And this is one of a series of paintings and so when Sassoferrato
created this image he was obviously, he knew what he was going to do precisely and so there
are no changes or adjustments and that the image in the x-ray looks very, very like the
image of the painting itself. And you see the density in the x-ray images of these areas
of white. This is painted in a pigment called lead white, which is very dense and opaque
to x-rays and that's why it registers so strongly. You can also see in fact the image of the
stretcher. Now, with modern digital technology we're able to take an x-ray and digitise it
and remove the image that interferes with the image of the paint layers, which helps
one interpret the x-ray rather better. Now, van Gogh's x-rays in the main are of the honest
kind. That is they're fairly easy to interpret in that a lot of his pictures are painted
very quickly. There are certainly adjustments made during the course of painting but they're
not always very dramatic and you see that the images of the... in the x-rays are very
close often to the paintings themselves. It's so for the National Gallery chair and it's
also so for a picture of 1889 of so-called wheat field with cypresses. And you can see
the great difference in density between the different kinds of paint. Now, what I'd like
to point out to you in this picture is that firstly the wheat field itself is very, very
dense to x-rays, so you'll see that appears white in the x-ray image, but the sky and
the clouds very much less so and the reason for that is that the pigments used for all
this beautiful tossing wheat is largely a pigment for chrome yellow and chrome yellow
is a lead-containing pigment. So like the lead white in the Sassoferrato, it's very
dense to x-rays, it blocks the passage of x-rays, and so when the x-ray's printed it
appears as light-coloured in the x-ray image. Now, you would think that you would have exactly
the same with the sky but that's not the case because the white pigment that van Gogh uses
for the sky is not lead white but another 19th century pigment called zinc white and
that happens to be less dense to x-rays and hence you see a much darker image in the sky
paint. And you can see that in a bit more detail there. And just to point out, these
lovely dabs representing poppies in the foreground are painted with a pigment called vermilion,
which is another very dense pigment to x-rays and you can see down here in this detail those
little touches of red containing vermilion. And also x-rays show not only where the paint
is present but they also show very clearly where paint is absent. So in this detail of
the chair you can see where van Gogh has designed the outlines of the chair. In fact there's
a bit of dark paint used rather like drawing to begin to make this composition. But he's
also left a space in effect where the paint is just brought up to neighbouring, adjacent
blocks of paint and as a result there's actually no paint there and hence those areas are very
dark in the x-ray image, and that's relevant to what we see in the x-rays of our two sunflowers.
Now, these are they, and one of the things that you see first of all is that if you look
in detail at how the sunflowers themselves are painted you see exactly that phenomenon
that you see in the chair, that is, there's a dark band around each bloom, here and here,
and it's so for both the National Gallery and the Amsterdam painting. And the reason
for that is that what van Gogh has done in designing these
pictures, he's begun with a sketch, possibly something like a charcoal sketch for the actual
bunch of flowers, and if you look through the microscope carefully at these spaces you
can actually see some of the black pigment of that sketch. So he's left what we would
call a reserve, a space for the bunch of flowers. And so when he's come to apply the paint he's
painted the background first and brought that up to the edge delineated by the sketch, filled
in the blooms themselves and then applied more paint in the background but still not
bringing it quite up to the point of contact with the sunflowers, and that's so for both
pictures. And it was really a new observation based on the x-rays and close observation
of the surfaces of these paintings. But there are other clues to the way these pictures
were painted from the x-ray images. Most particularly I'd ask you to look at these two hanging blooms
down here. This is the London painting, this is Amsterdam. And what you see here is that
these two flowers are light-coloured in the x-ray image and here they're dark and that
tells us definitively that the Amsterdam picture followed the painting of the London painting
because these are, as it were, an afterthought in the design of the picture. They weren't
left in reserve and so the flowers go over the
background, which means there's a lot of paint piled on there and therefore they appear light
in the x-ray. When he came to paint the Amsterdam version he'd left a reserve and so these are
dark, so we know absolutely for certain that the Amsterdam picture follows the London painting
and that he had already fixed in his mind the total design for the bunch of flowers.
The x-rays also show brushwork very clearly in ways that it's not always so clear on the
surface of the pictures. So both the London picture and the Amsterdam picture have a sort
of criss-cross basketwork like effect in the brushwork in the background. You can see that
very clearly. And you can also see the difference in the brushwork in the painting of the two
vases. Here it's sort of back and forth and horizontal and here it's vertical. So there's
a difference in the treatment of the paint in the construction of the two pictures. But
of course, although you can tell a great deal from looking at the internal structure of
a picture by using x-rays, there's no real substitute for looking closely at the actual
surface of the picture, and although you can see these details to some degree when you
peer at the paintings in the display with a little bit of magnification you can see
a great deal more, particularly features such as the way that there is actually a gap between
the parts of the paint that make up the vase here. You can certainly see this beautiful
highlight on the London picture but it's less easy to see the difference in the colour and
the texture, for example, in these two flowers, one of which is over the background, as I
explained, and the other is there left in reserve. But you can see a difference in paint
composition and colour and handling which emerges partly from looking at the x-rays
but much more clearly from looking at the surface in detail. So I shall now hand over
to Ella to talk more about colour, I think, and materials. So colour is really a very nice topic to talk
about in the context of van Gogh but particularly with the Sunflowers. And van Gogh's experiments
with colour and tone in the Sunflowers really come back to his knowledge of what are called
complementary colour contrasts. And he learnt about this through the artist, the French
artist Eugene Delacroix, who he greatly admired for his bold use of complementary colours.
For example, in this, what he called a brilliant sketch that he'd seen with the contrast of
the pale yellow halo of Christ with the dramatic dark blue and violet and blood-red figures
of the disciples in the boat against the emerald-green sea. So
highly emotive, charged use of colours. He'd actually read about complementary colour principles
early on in this handbook by Charles Blanc he'd read as early as 1884 when he was still
starting out as an artist in Holland. And this is the frontispiece of the book, which
was the most important book for his ideas about colour theory throughout his career
as an artist and it explains what's called the laws of simultaneous colour contrast.
So if you bear with me, I'll try to explain. So if you have two what are called primary
colours, so for example you have yellow and you have blue, and you mix them, you'll get
green. And if you place the green next to the third primary colour, which is opposite
on the colour circle, which is red, so if you place red and green next to each other
they'll act to strengthen each other, so you get a brighter and more vivid colour effect.
And you have the same if you, for example, place orange next to blue or yellow next to
violet. And this is something that van Gogh applied really very often in his paintings,
though never in a dogmatic way. Besides this so-called simultaneous colour contrast, tonal
contrast was the other important principle that he used a lot in his pictures, including
the Sunflowers, and in this early sketch he tries to explain what this involved. You can
hardly see it but there's a white thread running across here, which he's holding with his left
hand and this is the lightest part of the drawing. And van Gogh makes two splodges of
paint in the margin, which in fact represent the same white tone, the lightest tone in
the drawing, but he explains that the dots, the white dots can look darker or lighter
depending on the colour of the surroundings. So this one, for example, looks greyish because
it's in the light surroundings so it will reflect the light. Whereas this one is darker
or looks darker, it's actually the same white, because it's in a shadow surrounding. And
he plays again with this idea in the Sunflower series, placing the sunflowers against lighter
and darker backgrounds and adjusting the tones within the still life to achieve the correct
tonal relationship between the flowers and the background. This is one of the nicest objects that's come
down through the van Gogh family collection. It's a Chinese lacquerwork box with balls
of wool in different colour combinations and later the friend... van Gogh's friend and
artist Emile Bernard recalled having seen this in his studio in Paris. And so it's thought
that he used this to experiment with different colour combinations and we do find very close
parallels in the colour schemes of his pictures. And you also notice this little kingfisher,
so it's also a soft nest for this kingfisher, which I'll come back to a little bit later
since he actually painted it. So here's just some examples. These are three still lives
painted in Paris. I've put the balls of wool with the corresponding colour schemes next
to them and these are all painted very soon after each other in the same period of time.
But what we'll see is the two on the left are based on that theory of strong, simultaneous
colour contrast. So you have the green next to the red and the violet next to the yellow
in the bottom left. So he's aiming at maximal vivid colours next to each other. Suddenly
in the third still life he switches to a different approach. We call this the yellow still life,
which is in our collection. They're all in our
collection, actually. So he's now avoiding strong colour contrasts and switching to a
more tonal approach, building up the tones with different shades of the same yellow pigment,
chrome yellow. And this is reminiscent of the switch that he makes in the course of
painting this sunflower series when he does actually refer back to this yellow still life.
So these are the first three in the series, which are very much based on the idea of strong
colour contrast, particularly the one in the middle on complementary colours. I think I've
lost a text here, but in any case, so the yellow against different blue backgrounds.
And this is the one which has the most marked
use of simultaneous colour contrast. As he writes, one of the sunflowers on a royal � you
can probably read it much better than I can from here, but � on a royal blue background
has a halo. That's to say each object is surrounded by a line of colour, complementary to the
background against which it stands out. And we do see these orange contours, which is
a mixture of red and yellow. Again, the complementary colour to the deep blue background so really
creates a strong contrast to make the still life stand out more. This is a very nice reproduction
of this picture which was recently rediscovered by Martin Bailey and what's very unusual about
it is it seems to show the picture in its original frame. Van Gogh actually wrote that
the sunflower... that these sunflowers should be framed with simple lats painted with orange
lead and that seems to be what we're seeing here. And if you look carefully you can see
he's actually adjusted the colour of the frame against the colour of the background adjacent.
So here, for example, it's slightly lighter and here it's a slightly deeper orange and
at the top it's even a brighter red against the deep blue of the background. So he's looking
at the relationship, the contrast between the colour of the frame and the picture within.
In
Paris van Gogh had already hit upon the idea of painting colour borders as a cheaper substitute
for a frame to provide contrast. We know that this is the kingfisher that was in that chest.
He's actually missing a feet... missing a foot, sorry, which is why he perches rather
awkwardly since van Gogh had to invent it. And this picture was exhibited without a frame
and van Gogh added this painted red border, which would have originally been folded around
the sides of the frame to introduce again this simultaneous colour contrast between
red and green. And as for the sunflowers, for this picture too he also recommends that
it should be framed with simple lats painted with orange lead. And he calls the colours
of the picture, he compares it to a Scottish fabric, in other words a tartan, and that
the red will complete and add contrast to the dark greens and the bright blue in the
sky, for example, and compensate for the fact there's not much red in the picture itself.
Now, this is, of course, the London picture and so in the fourth version of the sunflowers
he suddenly switches to this more tonal idea of what he refers to as painting clair sur
clair, or light on light. So a yellow vase against a yellow background, a more gentle,
tonal approach rather than strong colour contrast. And he refers back to that still life that
he painted in Paris, the quinces and lemons, which is this work, which very uniquely still
has its original painted frame; it's the only example that we have. Which is painted in
similar colours to the still life. In fact the still life is painted on top of another
composition, which seems to have been a landscape. Here we look at one side of the painting and
we see a dark green layer that's been used to paint out something underneath. This is
a detail of the inside of the frame and we see paint that has been transferred from the
fresh landscape or the fresh painting that was placed in the frame before it was properly
dry. I show you this because we can now recognise this in the portrait of Pere Tanguy that van
Gogh painted. You can see that the first composition, and this is the turquoise colour that's still
left in the frame, and the frame, you notice, has a red inner edge. But when van Gogh used
the frame for the yellow still life he's actually painted over the red and also made it yellow.
You can see bits of the red peeping through, as it were. So he's drawing the colours of
the frame closer than ever towards the colours of the still life to create a more unified
ensemble. Now, van Gogh claims that for these first two sunflowers painted with yellow vases
that he used chrome yellows, yellow ochre, veronese green and nothing else. But that
nothing else should perhaps not be taken too literally since, well, we've been looking,
comparing the pigments used in the two versions over the years and in fact we've identified
13 different colours in all in the London picture but also in the Amsterdam picture
and they correspond. So in fact all these colours have been identified in both versions
of the paintings. And this is rather nice, it's a paint order that survived in the letters
when van Gogh was wishing to replenish his stock of paints having painted the first series
of sunflowers. So we might expect to find these pigments, these paints used in the pictures.
What I particularly want to point out are these three; chrome one, citron, chrome two
and chrome three, which are different shades of the chrome yellow pigment so that the lighter
shade would be one, which is a sort of lemon yellow, chrome two would be a deeper yellow
and chrome three a more orange colour. And these were ready-made tube colours that you
could purchase that had different chemical composition. So just to focus down in this
last bit on the series of yellow sunflowers. There are in fact, there's the original picture
here in London and there were two copies, one in Tokyo and the one on the right in Amsterdam.
And as you can see, the chrome yellows feature very strongly in all three pictures. To gain
an idea of the pigments used throughout the paintings and the different colour mixtures
used we were very lucky to make use of a relatively new technique, which is based... it's called
macro scanning XRF, x-ray fluorescent. So it's an x-ray based technique and what it
does is it scans the painting literally pixel by pixel, so to scan this painting took six
days and six nights, and it can detect the metallic elements in the paint layers, so
with some interpretation we can relate these to the pigments used. So just to give you
a visual impression, this is the scan for chrome and where there's increased density
of chrome, so more paint or a higher... a purer use of the pigment, it looks lighter
in the image. And as you would expect, the chrome appears pretty much throughout the
whole painting since yellow occurs throughout. But to distinguish the different types of
yellow we were fortunate through the National Gallery to engage this European-funded Charisma
project. So this is a team that travel around from Perugia with their mobile apparatus and
they were able to come to the painting and without taking any samples they could distinguish
successfully the different types of chrome yellow used on the painting on the basis of
chemical composition. Don't worry too much about the chemical composition but I just
want to give you an impression of the different shades, all three of which have been used,
for example, in this sunflower head. So you have the light yellow here, which is chemically
distinguished from this more ochre colour, which is presumably chrome yellow two, and
then you have the orange, which has been used for the hearts of the sunflower, which is
chrome yellow three. This was very successful to know this. It was information we didn't
have yet because up to now you've really had to take samples to be able to distinguish
between the different types. I think I'm missing a slide there, never mind. Sometimes he used
the chrome yellow pure but he also mixed it with different reds to create different orange
tones in the sunflower. Here is the scan for mercury, which is present in the red pigment
vermilion, mercury sulphide. And it shows you very nicely where this pigment has been
used, for example, in the red stripe along the tabletop but also particularly around
the edges of the flowers and around the edges of the hearts. That's only showing half the
slide, I'm sorry, but something got lost in translation. These bright spots really correspond
to these very tiny marks with vermilion that are brushed around the edges of the petals
into the background to draw the two together. He also mixed the yellow with minium, which
is the orange lead he referred to also for colouring the frame, for example. You can
see these rather lumpy pigment particles mixed with the yellow in this tiny paint sample
or cross-section, and you can actually see the same effect on the painting in this greatly
enlarged detail. This is one of the petals of the sunflower heads. So here just to summarise,
we have the chrome yellow which was mixed with these different red pigments, vermilion
or minium, to give these orange shades, but also with emerald green to give a greenish
tint, and if you mix all these together you get these, sort of, brownish colours. And
if we hold this next to the painting I think you'll agree that it does give a very close
comparison to the different shades of yellow, orange, green, which van Gogh has used to
model in great detail the sunflower heads with these brushstrokes on top of each other.
If we look at the series of the three yellow still lives, one of the main differences that
you'll notice also if you look at the two next to each other in the gallery is that
the background colour of the London picture is much lighter. There's an almost imperceptible
veil of yellow on a creamy colour. In the Tokyo the background has become much more
greenish, more saturated. And the Amsterdam picture shows a combination of both, so it
consists of a green layer on top of a light yellow layer. The green is applied with this
very nice basketwork brushstroke that Ashok described, but you can see this brighter yellow
pocking through in between underneath, so really two layers. So in the coppice the background
has a slightly darker, more saturated colour compared to the London picture and accordingly
he's adjusted... he's lightened the green colours within the still life to maintain
a contrast with the background. This is a scan which shows in which areas he's used
what he would call... what he refers to in the
orders as a veronese green, which contains copper and arsenic. It's not a pigment that's
used today because of the arsenic; highly toxic. But it shows very nicely, it maps out
the, sort of, areas of the stalks and the leaves where this particular colour was used.
And if we compare the London picture with the Amsterdam with this heart in the middle,
I think you'll agree this looks darker but it's also much more thickly built up, whereas
in the Amsterdam picture it gets an almost abstract quality. It's just a very thin, single
layer of bright, emerald green mixed with zinc white to lighten it and a little yellow.
And in fact Gauguin later referred to these as green eyes, so it had a very mysterious
quality. Another difference between the two, van Gogh has added a little colour accent
in the copy, in the Amsterdam picture, this blue. But if we look very closely in fact
we see the blue was mixed originally with a little red lake, which you just see a bit
where it was not completely mixed with the white paint. You can see it here. And this
red lake pigment has faded. It's been identified as a geranium lake, which was a synthetic-based
pigment, a relatively new pigment invented in 1873 and van Gogh was well aware that this
was not a light-fast pigment. He actually ranks it amongst the unstable colours brought
into fashion by the Impressionists. But it didn't stop him using it because he's ordered
something like 38 tubes in the period 1888 up to his death in 1890. So often it's led
to colour change in his paintings. Now, even when the colour is gone on the painting the
nice thing with this technique is that we can still sometimes see where it's been used
because of the bromine that it contains, if it's been used in a high enough concentration.
In fact this bright white spot corresponds to that detail I showed you in the heart.
And you can see the same pigment's also been used for this quite colourful heart of this
sunflower as well, and note also along the line of the tabletop. Now, this is a beautiful
cross-section that Ashok prepared and I think just to give you some idea of the strong intensity
of the colour, this is a tiny sample from the line along the tabletop that was taken
in the early nineties, and you can see the very intense colour towards the surface where
it's applied in a, sort of, very pure technique. Another difference between the London picture
and the Amsterdam picture is that the vase has now taken on a pinkish colour rather than
yellow and possibly this was to draw it closer towards another copy, which is now in the
Philadelphia Museum, which has a purplish vase. Since around this time, as I think Christopher
is going to come back on, there was some idea of hanging these two pictures side by side
as part of a triptych, so it would have perhaps drawn them more together. He's also replaced
the blue contour of the table in the London picture with this red, which again agrees
more closely with this version. So here we see the London vase on the left, Amsterdam
on the right, and they both have these blue contours with blue signatures. But again if
you look very closely at the signature we can see in this detail, looking with the microscope,
this is a microscope that magnifies very strongly so it's about 800 times magnification and
it shows this little detail in the N where there is actually red lake mixed with the
red, which has again been identified as the geranium lake. So this signature too would
originally have been more purplish, in contrast with the yellow. And this is a tiny paint
sample that also proves that from the blue line on the pot. And I admit it's not very
much but a single particle with geranium lake you can still see at the surface of the paint,
proving that the blue was mixed with the red. And indeed van Gogh quite often added signatures
to provide a strong colour contrast, as in this picture that he painted soon before,
where he talks about the outrageous signature because I wanted a red note in the green.
So that's just gone through some of the differences between the London and the Amsterdam version,
and as Christopher was talking about in repetition, it was not literally a copy but there were
subtle modifications made searching for colour and tonal unity within the individual pictures.
So it was not... he was not aiming to make a naturalistic rendition of the colours that
he actually saw but he felt that the colour expressed something in itself and that you
should be led by the colours on your palette. As Ella said, in 1889 Vincent had a further
idea of what he could do with these pictures. We have seen how formally inventive he was,
how formally experimental in the way that he went about painting and the, always thinking
about the ways he could achieve effects in his canvasses, but he was not a formalist.
His paintings always had meaning, he wanted them to express things. He wanted them in
a very real sense to help people. And one of the most poetic ways in which he did this
emerges in 1889 with his paintings of sunflowers. Having gone through this crisis of the fight
with Gauguin, his own breakdown, he returns to painting sunflowers. He paints Amsterdam
as a repetition of the London painting. He paints Philadelphia with its bluish background
as a repetition of the Munich picture and then he decides that he could form a triptych
of those two pictures and in the middle one of his portraits of the wife of the postmaster
Roulin La Berceuse, the nursemaid. You see in her hand she has a rope and it's actually
attached to a cradle and as she pulls the cradle... pulls the rope, the cradle with
her baby in it will rock. And wonderfully, as I say, poetically, van Gogh decided that
this triptych would be helpful for fisherman off Iceland; on their boat in this rough and
rugged sea this image of sunshine, of hope, of all those things the sunflowers meant would
correspond to this image of their mother rocking the cradle and so even the rocking of the
boat on the sea would become like their mother rocking them in entire safety. As I say, it
is a wonderful invention, never realised, but always reminding us the ways in which
van Gogh wanted his work in a quite literal way to help us. So we'll stop now, having
looked at a very great deal of information, a very great deal of it quite new that many
of us are hearing for the first time, and invite questions from the floor. If I may
start with my own question to ask Ella; you've referred a number of times to alterations
in colour. Do we have any sense of how much alteration we're looking at when we look at
these pictures in 2014? That's a topic of ongoing research, as they
say. We know that, well, I talked a little bit about the geranium lake. We know that
a lot of van Gogh's pictures in the period 1888 to 1890 have been affected by discolouration.
We have a picture, Vincent's bedroom, in our own collection where we were able to put together
bits of evidence of preserved colour in paint cross-sections on the picture and we made,
working together with a colour scientist we were able to make a digital reconstruction.
And quite frankly it was really an eye-opener because the background walls are now blue
but originally they were,as he described in the letter, they were violet and this had
a very strong impact upon the composition. So with the violet background it was much
flatter, more like a Japanese print, as he actually described in the letter, for example.
The other question is with the chrome yellows that painters in that period knew, were very
aware of the fact that some types of chrome yellow could darken under light exposure,
and Delacroix actually writes about this. He talks about the chrome yellows turning
green or gold over time and van Gogh had read this and he also talks about the dreadful
chrome yellows but still wants to use them because of the beautiful colour effects that
Delacroix can get with them mixed with Prussian blue, for example. And that question, to what
extent those have darkened, we've done a lot of research and we now know which particular
type of chrome yellow, it tends to be the light shades that are more light-sensitive.
But we're still relating this experimental data, which is done with paint reconstructions
and artificial ageing, so they thrash [?] paint out, so they bombard it with high doses of
light and ultraviolet to induce this ageing effect. And it might not be exactly the same
as what actually happens in real life on paintings with different colour mixtures. So we're at
the stage that we're trying to relate this to what we see on the paintings. So I can't
give you a clear-cut answer as yet. But if I'm not speaking out of turn, I understand
that you at the van Gogh Museum are very much thinking about showing your collection in
much lower levels of light than we are used to. Yes, I think that's the point of doing all
this research, that we do have strong indications that some of the pigments that van Gogh, not
just van Gogh but his contemporaries because they were using often the same types of tube
paints that could be bought anywhere, and some of these colours are known to be very
fugitive and equivalent to, for example, watercolours. And we're all used to seeing watercolours
exhibited at much lower levels of illumination but that's not yet a tradition for 19th century
oil paintings which contain these sensitive pigments. But we know enough that we have
to start taking measures if we want to keep these colours, preserve them for the future,
that we are implementing lower lighting conditions. Can I ask for any questions from the floor?
Yes, please. Let me repeat that, in the long-term is this use of heavy impasto a detriment to...? In terms of colour? Well, of course, he actually
talks about, for example, the geranium lake, applying it extra boldly, so extra thickly
to compensate for the effects of colour change. So in terms of colour change it will help
because when the surface of the paint � of course, it gets exposed to the most light
� discolours you'll still have a thick body of paint underneath that has that colour intact.
So it will still look as if it's quite bright. He himself was worried about the thickness
of his brushstrokes not adhering to the poor quality of the canvasses, these thin canvasses
he talks about. I think that's a hard question to answer because most of these pictures have
already been treated in the early 20th century, certainly in Holland and
certainly in our collection they've been wax resin lined so all the paint has been firmly
stuck to the canvas and encased in this wax resin. So whether it was really necessary,
whether... is now difficult to answer I think. Yes, please.
[Inaudible]. The only addition that we've been able to
make is that we've done further research on the canvas using, I don't know if you're aware,
these new computer techniques that you can actually very precisely characterise canvas
weave and this has confirmed what we already said in that paper, that it's cut from the
same roll, that the canvas used for this picture is cut from the same roll of jute. But unfortunately
the owners of that painting have not given permission to do a full technical research
so we've not brought it further than what we've already published. In our paper it's
not debatable, that's our opinion. [Inaudible]. Of course, that's everybody's right. Can I add, actually, that there's an x-ray
of the Tokyo picture and for what that's worth, I mean, that makes it look very like the way
van Gogh applies paint and you can't really falsify that, in a sense. If you look at the
internal structure of a picture, you might be able to make the surface look convincing
but it's very hard to make the, sort of, whole skeleton of the object look like the work
of another painter. So I think that is some evidence for its authenticity. And the fact
that it's on a jute canvas and apparently of the same weave I think is also quite strong,
yes, quite strong evidence. And I would just add that what is now the
Tokyo picture hung on our wall upstairs beside our picture for ten years and no-one ever
questioned it. It's only when they were 5,000 miles apart that anyone began to question
it. Yes, please. The use of this yellow and sunflowers in relation to his emotional state
at the time? Certainly as I said at the beginning, he formed the studio of the south, he says,
where he would paint in the Japanese manner and more and more information about Japanese
art was available to artists who were curious about it, like van Gogh and his circle in
Paris and even further afield. So it would strike me as very possible that he would have
learned of and have been quite fascinated by, if you will, Japanese iconography and
how they would have used the colour and it would be just the sort of thing he would want
to incorporate into what he saw as his revival of painting in that mode. Yes, at the very
back. The question is about whether an x-ray image
which reveals another image underneath is simply to do with modification of a picture
or it's to do with reusing a canvas. Well, you get both situations when pictures are
painted. In the case of the Titian, although those apparent legs were not part of the original
composition we would call them an artefact in the image. They're not really part of the
image that was being painted. There are other changes in the work by Titian which are completely
intentional. They are to do with evolving of composition and you can see in which the
way in which the composition has evolved in the x-ray in that case. So although you can't
with an x-ray tell at what stage a particular modification takes place because the image
is the superimposed image of all the paint layers and there's no way of knowing at what
level in the paint structure any particular layer exists and at what point in the evolution
of the composition in particular the change was made. However, you certainly see a lot
of intentional modifications in a picture like that. Whereas the picture by one of the
Le Nain brothers is apparently just a complete reuse of a canvas. A portrait was painted,
it was then recycled. The picture was turned into landscape format and another picture
put on top. Now, it's very common and this is not a very uncommon thing to see in early
pictures. It's usually the case that a painter who's going to do that obliterates the earlier
image with a new priming, because you can imagine if you're going to paint on top of
another image it's very disturbing to have that image disappearing, as it were, as you
create the new image. But there are painters, in fact, who don't necessarily prime over
an earlier image to carry on painting and we've got a very well known case in the gallery.
There's a picture that has sometimes been attributed to Goya. It's a painting of a sitter
called Dona Isabel de Porcel, and she is painted over an image of a male portrait and there's
no priming between the two. And the person who painted this picture, I think it's not
any longer thought to be by Goya, or the picture underneath may be but the surface painting
probably isn't, whoever did the surface painting didn't even turn the picture upside down in
order to do it, which is a very extraordinary thing to do. And if you go and peer at this
picture in the gallery over time oil paint becomes slightly more transparent so you can
begin to see something of the under layer sometimes through the surface of the paint.
And in a very, sort of, sinister way you can just about see the eye of the male portrait
appearing through the neck of Dona Isabel. So it's a very extraordinary, sort of, phenomenon
in this case. But there is a case again of an image being recycled. Good, one last question. I think very much
so and I think the title of Martin Bailey's recent book assessing the whole sunflower
phenomenon, The Sunflowers Are Mine, suggests that this was indeed something that Vincent
recognised as a motif that he could really do something with and indeed people like Gauguin
were telling him how important this was for him. And I think any artist is very keen to
find something that is particularly expressive for them. Good, so, well, thank you all very
much for coming, and I thank Ella and Ashok for this wonderful new information we are
receiving. Thank you.
