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  THE STORY OF THE SKELETONS

  Lead is not only poisonous; it is also—when suspended in water-based media—not even particularly stable. When Cennino described this particular “brilliant” paint in his Handbook he included a warning. It should be avoided “as much as you can . . . For in the course of time it turns black.” There are many examples of when an artist has not heeded his advice and the lead carbonate has lost its oxygen and turned into black lead sulphide. But the most startling examples of lead blackening I have seen were in paintings done six hundred years before Cennino lived and an entire trade route away—in the sacred caves of Dunhuang, in western China.

  Dunhuang today is a remote town in Gansu province, an hour’s flight and about 1,800 kilometers by camel from the start of the Silk Road in Xian. If it weren’t for its famous caves, it would now be forgotten. But in the eighth century this oasis in the Gobi desert was one of the busiest towns in China, full of merchants, monks and mendicants. It was the place where the northern and southern Silk Road routes divided, and it was known for its good food, excellent markets and, most importantly, the chance it gave to buy favors with fate by becoming an art patron through sponsoring a fresco.

  The Mogao caves are 20 kilometers from Dunhuang across a desert full of graveyards. Today the Chinese government presents them as a series of art galleries, great painted treasure houses in the desert. But thirteen hundred years ago they were holy places, and Mogao was a city of shrines. At one point there were more than a thousand caves here, painted between the fifth and eleventh centuries. They were mostly paid for by people making bargains with the divine. The pacts would often be on the lines of: “if I get to Kashgar with my camels/ if I have a son/ if I win an inheritance . . . then I will sponsor a new painted cave.” Some caves, of course, were painted for more spiritual reasons. These were a celebration of the transcendent, without earthly terms and conditions, and they are probably the finest.

  As recently as the 1970s, the 492 remaining caves were visited only by the lucky few. In his book about the raids on ancient Chinese cities— Foreign Devils along the Silk Road—published in 1979, Peter Hopkirk described how occasional tour groups and scholars would traipse freely around the picturesquely rickety scaffolding. They could mostly shine their torches wherever they wanted, to discover for themselves the magical images of azure fairies swooshing energetically over the ceiling, or ancient depictions of the Buddha sacrificing his body to save starving tiger cubs.

  Today the caves are rather like a cultural motel. The exteriors have been squared up and covered with a pebble-dashed façade, each grotto accessed by a metal hotel-style door, with a room number outside. Young female guides in short turquoise skirts trip along the concrete balcony paths with torches, visiting the same ten or so caves each time. Every year the authorities sensibly change the tour itinerary, to preserve the murals. On a summer’s day, with so many humans breathing in them, the smaller ones can be like a sauna.

  The guide escorting my group was so bored that while she was waiting for us to move from one cave to the next she kept having a little snooze with her head resting against the door. But her sense of tedium was not contagious, and inside, once the nasty door had opened, the caves were full of visual treasure. It was hard not to be entranced by the ancient Buddhas painted in bright malachite greens, their haloes luminous with blue or even with real gold leaf—in the places where the fleeing White Russians didn’t scrape it off with their penknives in the 1920s. We had to stay alert to see even half of the murals: a few minutes’ chat, some quick flicks with the flashlight, and the group was ushered out blinking into the desert sunlight.

  In some caves I had to be dragged out of the grotto, the last to leave. But others were disappointing. This was among the most prized Buddhist art in China, and some of it, especially some of the paintings from the Northern Zhou period in the sixth century, looked like slightly ludicrous children’s cartoons, with harsh black outlines. In cave 428 there were pictures of enlightened beings who looked like joke skeletons in reverse. Their crudely daubed black bones, limbs and bellies contrasted curiously with the delicate folds of their headwear and robes—it looked as if a primary school student had helped with the artwork. Meanwhile cave 419 was full of holy men and Buddhist fairies whose faces were startlingly black. And, even more odd, outside cave 455 there were some frescos painted minimally in navy, black and white, looking more like an indigo textile from Nigeria than a Buddhist painting from China. What had gone wrong? Had they been overpainted by later restorers? Or was this just the style of the Northern Zhou?

  Cennino warned his artists not to use lead white on frescos at all. But then he warned them not to use yellow orpiment, red vermilion, blue azurite, red lead (which is what you get when you heat white lead) or green verdigris either. So the fresco painters of Dunhuang—who used all of the above—seem to have got off remarkably lightly, considering. Most of the paintings are still almost as bright as they were 1,400 years ago. But the worst damage can be seen where white lead or red lead12 paints have come into contact with hydrogen sulphide, and have oxidized.13 Those odd figures I saw in cave 428 had once been a pale shade of pink, the lead paint just a subtle lowlight on the skin in an attempt to make the paintings more realistic.14 It was only over the years that the pink flesh turned to blackened bone: an intriguing example from 1,400 years ago of how art follows life.

  THE SACRIFICE OF THE FIVE-PIGMENT GIRL

  The local people of Dunhuang have their own version of where the pigments came from. It contains the elements of the best folk stories: a crisis, a deity who appears in a dream with a dangerous solution, and a virgin who is willing to risk everything for what she believes in. It was recorded by Chinese anthropologist Chen Yu in the 1980s, and was set in the eighth century. At the time, Mogao was attracting tens of thousands of people, who came to seek their fortune there. Among them were the widower Zhang and his teenage daughter. Zhang was one of the most talented artists in China, known for his exquisite apsaras fairy figures, which floated over turquoise skies as if the breath of the Buddha were guiding them. The most powerful warlord in the area, His Excellency Cao, had heard of the reputation of this father-daughter team, and had hired them to paint a new cave. There was one condition. They had to finish by the Buddha’s birthday on the eighth of April. Easy, thought Zhang, and said yes. They spent days balancing on scaffolding, painting the most exquisite images. But the most beautiful painting of all was their deity Guanyin, who radiated compassion throughout the cave.

  And then, disaster. They ran out of paint. They ran out of the white for the Buddha’s body, and the green for his ribbons. There was no blue for the robes of his attendants, no red ochre for his face, and no black to draw the outlines of his enlightenment. It should not have been a problem: Dunhuang was a major stopping point on the Silk Road. In a normal year there would always be merchants in the marketplace selling sachets of vermilion and malachite and orpiment and all the other precious pigments that artists needed. But this was not a normal year: hundreds of artists were staked out in the caves and in tent cities around them, painting to the same deadline. The only paints available were cut with dross to make them go farther, and were unusable.

  Zhang and his daughter knew the penalties for not finishing on time. His Excellency Cao was not a man known for his kindness and patience. They were sick with worry. Then one night the daughter dreamed she was in a high valley of the San Wei Mountain, not far from Dunhuang. In her dream she was surrounded by powdered pigments of every possible hue, but every time she tried to pick them up they would slip out of her hand. Then the Guanyin of her cave painting appeared. There were plenty of pigments in this valley, the deity said. But only if the girl had the courage to find them. She said she did, and was given instructions to go to the bottom of a well, a special well, which was hidden beneath white sand and protected by black cliffs. Only a girl could descend the well, the deity said. Only someone who was pure could find the pure colors.

&
nbsp; The next day the girl and her father and their two assistants went on an expedition to this monochrome landscape. They tied her carefully to a piece of rope and eased her down. She was only halfway into the well when the knot slipped and she tumbled to the bottom. The last thing she must have felt was the thin stone at the base as her body crashed through it, because when the grieving father looked down all he could see was a gushing new spring, from which flowed the five pigments he had prayed for. Black and red, green and blue and, of course, the precious and pure white, all flowing out in a magical waterfall of paints.

  It is of course a superbly Confucian morality tale of individuals sacrificing their lives for the good of society. But it also shows that the local people were asking the same question that art scholars would later ask: where could all those wonderful colors have come from?

  THE ADVENTURES OF LANGDON WARNER

  My guide at Dunhuang was most animated in cave 16, where there were some hideous early-twentieth-century restorations, making some of the Buddhas look like Teletubbies, with unskillfully touched-up eye-dots. But it was not this that she was referring to. “One of our statues is missing,” she said ominously, waving her hands to where a Tang dynasty Buddha was waited on by an asymmetrical gathering of just three attendants rather than four. “The American stole our treasure.”

  “The American” was a young explorer-archaeologist called Langdon Warner, who had gone to Dunhuang in 1925, sponsored by Harvard. And the main reason he had been sponsored to travel so far and for so long, risking his life journeying through a country that was going through a particularly violently anti-foreigner phase,15 was because the university was anxious to learn about the pigments. Were they local colors, or were they carried for long distances? Did the colors change or did they stay the same for the six hundred years that there were artists at Dunhuang? The story of the paints was the story of the ancient trade routes, Warner’s pay-masters at Harvard had decided. And they wanted to know it.

  Of course, Harvard’s eminent scholars were also hoping for something more concrete in exchange for their sponsorship dollars. They wanted a share in the archaeological loot that Europeans had been taking out of China by the donkey-load. The Hungarian-British archaeologist Marc Aurel Stein had started the looting when he arrived in 1907 to find that a few years before a monk had accidentally discovered a secret door, that revealed a secret library room, full of ancient documents. Stein took about eight thousand of them—everything from Buddhist sutras to early Eastern Christian writings to a timelessly useful model letter to send to your host apologizing for drunken behavior the night before. He was closely followed by the polyglot Frenchman Paul Pelliot, some Russians and a number of Japanese explorers, who seemed to be working for a mysterious cult. They all took souvenirs, which nowadays are in the proud possession of various national museums, but none of them actually gouged paintings out of the walls of Dunhuang.

  Langdon Warner did. He cut out several paintings. Partly because that was the only way he knew to collect pigment samples. Partly because he was shocked at how a few years before a band of White Russian soldiers had covered the caves with graffiti, and he had the idea of saving art from vandals by becoming a vandal himself. But most of all he took the murals because he was determined that he had not gone all that way “Plodding beside my cart these weary months” to fail in his mission.

  Not only did he cut out those ugly square holes, but—and the Chinese find this the hardest to forgive—just as he left Dunhuang he caught sight of an exquisite kneeling Bodhisattva. He was so taken by its beauty that he took it too, wrapping it up in blankets, sheepskin breeches and his undergarments. “If I lacked for underwear and socks on the return journey my heart was kept warm by the thought of the service which my things were performing when they kept that fresh smooth skin and those crumbling pigments from harm,” he wrote in his account of the journey.16 The Bodhisattva is, of course, the missing attendant in cave 16, and the gap where it used to kneel is pointed out to every tour group today to explain why China considers that the nation’s “heart was broken” (as an inscription in Chinese characters at Dunhuang asserts) when the foreign archaeologists took its art in order to learn more about the colors.

  WHITER SHADES OF PALE

  Rutherford Gettens, chief chemist at the Fogg Museum when Warner’s stolen Bodhisattva arrived, called lead white “the most important pigment in the history of Western painting” and was thrilled to find it lying “thickly” on the precious sculpture.17 He was grateful to it—as many art historians are grateful—because x-radiography of old paintings depends on the artist’s generous use of lead. X rays are electromagnetic waves, just like light except they have a much smaller frequency than light and so can pass through more objects.18 Lead, however, is dense, so it shows up in x-radiographs much more than, say, ochre. So, for example, in The Death of Actaeon by the sixteenth-century Venetian artist Titian, the painting shows Diana getting her terrible revenge on a hunter whom she has caught spying on her while she was naked. She transforms Actaeon into a stag, at which point the hunter becomes the hunted. With the benefit of x-radiography we can see that Titian had some problems with painting the poor hunter. In trying to portray that critical moment of the man changing form, the artist himself made many changes to the form of his painting, and there is a swirl of painting and overpainting in white lead over Actaeon’s area of the canvas, which presumably only stopped when Titian was satisfied with the effect of a no doubt extremely penitent peeping Tom being mauled by his own dogs.19

  As Michael Skalka at the National Gallery of Art in Washington explained, conservators today rarely see a painting that is five hundred years old that hasn’t been damaged or had some restoration performed on it. “People who worked on paintings in the past had very little training—and there was no code of ethics to give them rules about the right things to do,” he said. They felt they had the right to do anything—scrub the paint, change garments or hat styles—which is very different from current practice, where conservators work on securing and preserving the original paints and supports, without adding anything new of their own. With techniques like x-radiography, art experts now have a “road map” of the past of a painting. For example, a sixteenth-century painting in the National Gallery collection titled The Feast of the Gods has been worked on by three artists. It was painted by Bellini and then altered by the court artist Dosso Dossi, and later by Titian, who added a dramatic mountain landscape to the left of the canvas, covering Bellini’s original band of trees. It is possible to see many of these stages of the painting’s development by looking at the x-radiographs, as well as making cross-sections and doing pigment analysis. “It’s like a geology of layers,” Skalka said, “and you need to use science to excavate it.”

  It is undeniably useful for conservators, but if white lead did so much damage, why did so many artists use it? Certainly not to make it easier on future art historians. The simple answer is that there was very little else. In fact, in Europe at least, there was nothing else very promising in the white line for watercolors until the 1780s—and nothing to replace white lead in oils until just before World War I when titanium paint was invented.20

  There was bone white (from burned lamb bones) but artists found it gritty and gray. Then there were the “shell” paints, made of seashells, eggshells, oysters, chalk21 and even pearls. The Japanese and Chinese liked these whites, and they can be found on many woodblocks and paintings, even though they often believed the best white was the paper, unpainted. European artists often used chalky whites on frescos. In the early nineteenth century the English chemist Sir Humphry Davy travelled to Italy to examine the wall paintings at Pompeii. Most of the visitors (who had been including Pompeii on their Grand Tour of Europe since the site was opened in 1748) were full of wonder at the subject matter of the frescos that covered the walls of almost every wealthy home in that doomed Roman town. They showed beautiful objects, languorous gods, luscious gardens, and plenty of erotica. But Dav
y was more interested in the pigments they used, and he was disappointed to find that all the whites were made of chalk, not lead, even though “we know from Theophrastus, Vitruvius and Pliny that [lead] was a popular color.” But the ancients had been right in their choices: chalks and limes didn’t alter, and unlike lead white they could even be used safely with yellow orpiment. Those were the advantages. The disadvantages were that chalk whites look very transparent—anemic even—in oils, and don’t have the texture and shine of lead.22

  In 1780 two Frenchmen started trying to find a good white that did not have corruption at its heart. Monsieur Courtois was a science demonstrator at the Academy of Dijon and Louis-Bernard Guyton de Morveau was a magistrate who would later be better known as one of France’s most innovative chemists. A spirit of social activism was raging through Europe in the wake of America’s Declaration of Independence (and nine years later both men would support the French Revolution, with Guyton de Morveau rapidly dropping his “de Morveau”) and this activism extended into paint. Lead white was made by the poor and it poisoned the poor. Was it not time to find an alternative?

  They experimented for two years. The newly discovered element barium, when combined with sulphur (to make barium sulphate), made a non-poisonous paint that was reasonably permanent; indeed in 1924 it would be given the name “blanc fixe.” But barium was rare, and artists didn’t much like it as an oil paint as it was too transparent. So they turned to zinc oxide, a substance that the Greeks had used as an antiseptic. The first findings were promising: artists pronounced the color good and the absorption excellent. But the issue was cash: lead paint cost less than two francs a pound; zinc white was four times this amount. Nobody wanted to buy it.