by Ross King
Such was the regard for Perugino’s fresco that, soon after its completion, it assumed a mystical significance. The Sistine Chapel was – and still is – used for conclaves to elect a new pope, when rows of small wooden cubicles were constructed on the floor, turning the chapel into a kind of a dormitory. Inside these small cells the cardinals could eat, sleep and scheme. The cubicles were assigned by lottery a few days in advance of the conclave, and certain of them were held to be luckier than others. Particularly auspicious, was the cell beneath The Giving of the Keys to St Peter, probably because of its subject matter.1 There may have been something to the superstition, given that in the conclave beginning on 31 October 1503, the cardinal who drew the cell beneath Perugino’s fresco was Giuliano della Rovere.
Michelangelo climbed past Perugino’s masterpiece – and past scenes by Ghirlandaio, Botticelli and the rest of the team – each time he ascended the ladder to his scaffold. And one thing that must have struck him about these scenes was the brilliance of their pigments. Plenty of gold and ultramarine had been used in the frescoes, making for an array of splendid – even somewhat gaudy – colour. It was said that Sixtus IV had been so dazzled by Cosimo Rosselli’s use of these pigments that he ordered the other artists to follow his example in creating scintillating displays.
According to Vasari, Michelangelo was determined to show that ‘those who had painted there before him [i.e. in the Sistine Chapel] were destined to be vanquished by his labours’.2 Ordinarily, he had contempt for those who used great splashes of colour in their paintings, condemning ‘those simpletons, of whom the world is full, who look more at a green, a red or similar high colour than at the figures which show spirit and movement’.3 Acutely aware, however, that these same simpletons would compare his own work to that of Perugino and his team, he seems to have made a compromise, using an abundance of ravishing colour on the vault of the chapel.
This dramatic use of pigment would be especially pronounced in the case of the spandrels and lunettes, that is, the areas above and around the chapel’s windows, which are closest to the walls. With The Flood finished sometime early in 1509, Michelangelo did not yet backtrack towards the door, since he was evidently still leery of working on the more conspicuous sections of the ceiling. Instead, as would become his habit throughout the painting of the vault, after completing the central panel with its episode from Genesis he painted the scenes lateral to it.4
Michelangelo planned to illustrate the spandrels and lunettes with portraits of the Ancestors of Christ, the biblical characters listed in the opening verses of the New Testament as the descendants of Abraham and forbears of Christ. Each pictorial field would be frescoed with several figures, both male and female, adult and child, making for a series of family groups whose identities are suggested by nameplates on the lunettes. These portraits were destined to appear just inches above the spaces between the windows where Perugino and his team had frescoed portraits of thirty-two popes – one of which even wears a robe with orange polka dots – in a full spectrum of gorgeous, vivid colour. Michelangelo planned to dress the Ancestors of Christ in the same sort of bright costumes. Eager not to let his own work be overshadowed by an older generation of artists, he needed to find top-quality pigments.
An artist was, of course, only as good as his paints. Some of the best and most famous pigments came from Venice, the first port of call for ships returning from the markets of the Orient with exotic materials like cinnabar and ultramarine. Painters would sometimes arrange with their patrons to travel to Venice in order to fetch the necessary colours. Pinturicchio’s contract for the frescoes in the Piccolomini Library had set aside two hundred gold ducats for this purpose.5 The cost of travel to Venice would be offset by the fact that pigments could usually be bought more cheaply there due to reduced transport and distribution costs.
Michelangelo, however, typically chose to get his pigments from Florence. Ever the perfectionist, he fretted about their quality. Sending his father money to buy an ounce of red lake, he stipulated that the colour ‘must be of the best obtainable in Florence. If there is none of the best quality to be got, then do not get any at all.’6 This kind of quality control was essential because many expensive pigments were adulterated with cheaper ones. Anyone buying vermilion, a pigment made from cinnabar, was advised to purchase it by the lump rather than as a powder, since powdered vermilion was often cut with minium, a cheaper alternative.
It was natural that Michelangelo should have looked to his home town rather than Venice, where he had few, if any, contacts. There were some forty painters’ workshops in Florence7 and, to feed them with pigments, numerous monasteries and apothecaries. The most famous makers of pigments were, of course, the Gesuati friars. But a visit to San Giusto alle Mura was not always necessary to find colours. Painters in Florence were members of the Arte dei Speziali e Medici, the Guild of Apothecaries and Doctors. The logic behind putting artists in this particular guild was that apothecaries sold the ingredients for numerous pigments and fixatives, since many of them doubled as medicines. Gum tragacanth, for instance, was prescribed by doctors for coughs, hoarseness and weals on the eyelids, but it was also widely used by painters to suspend their pigments. And besides its use in red lake, the root of the madder plant was also promoted as a cure for sciatica. A comical overlap between pigments and medicines is found in an anecdote about the Paduan artist Dario Varatori, who was once painting a fresco while being under the care of his doctor. Taking his draught of medicine to work, Varatori sniffed the concoction, then promptly dipped his brush into the bottle and began slathering the solution on to the wall – apparently without harming either the fresco or his health.8
The manufacture of pigments was a tricky and highly specialised business. For example, one of the colours produced by the Gesuati friars – and used by Michelangelo for the sky and waters of The Flood – was smaltino, a pigment made from pulverising glass tinted with cobalt. Making smaltino was messy and even dangerous, since cobalt was both corrosive and, because it contained arsenic, poisonous. (Such was its toxicity that one of its other uses was as an insecticide.) However, the Gesuati friars, whose stained glass was famous throughout Europe, were skilled in handling cobalt. They would roast the ore in a furnace (hence the name smaltino, or ‘smelt’) and then add the resulting cobalt oxide to molten glass. Having coloured the glass, the friars would crush it to make pigment. This powdered glass is visible if a work painted with smaltino is examined in cross-section under a microscope. Even a fairly low magnification reveals both splinters of glass and tiny air bubbles.
Purchased by artists in an unrefined state, pigments such as smaltino needed to be specially prepared in the studio before they could be added to the intonaco. Condivi’s declaration that Michelangelo ground his pigments himself is extremely dubious, since preparing pigments was a task that always called for several hands. In Michelangelo’s case, it also called for the advice and expertise of his assistants. Like most of his helpers, he had learned these tricks of the trade at the feet of Ghirlandaio. But as almost twenty years had passed since he had used many of the pigments needed for the Sistine ceiling, the experience of men like Granacci was essential.
The type of preparation varied for each pigment. Some were pulverised into fine powders, others left in coarser grains, still others heated, dissolved in vinegar, or repeatedly washed and sieved. Since the tone of the pigment depended, like the taste of coffee, on the grind, it was vital to find the right consistency. For example, if smaltino was coarsely ground it produced a dark blue, while a finer grind yielded a much paler tone. Moreover, if left coarse-grained, the smaltino needed to be added while the plaster was still wet and therefore adhesive. For this reason it was always the first colour applied, though a second coat might be added a few hours later to darken it. Such tricks could spell the difference between the success or failure of a fresco. Not having used smaltino in his only recent encounter with a paintbrush, his Holy Family, Michelangelo must have leaned heavily
on his assistants when the time came to prepare it.
Most of the other pigments used on the Sistine ceiling were somewhat simpler to prepare.9 Many were concocted from clays and other earths excavated in various parts of Italy. Tuscany was particularly rich in this regard. The variety of colours found in its soil was described by Cennino Cennini in Il Libro dell’arte, a handbook for painters written in the 1390s. As a boy, Cennini was taken by his father to the bottom of a hill in the Val d’Elsa, near Siena, where, ‘scraping the steep with a spade’, he later wrote, ‘I beheld seams of many kinds of colour: ochre, dark and light sinoper, blue and white … In this place there was also a seam of black colour. And these colours showed up in this earth just the way a wrinkle shows in the face of a man or woman.’10
Generations of pigment-makers had learned where to find these clays and then how to turn them into pigments. From the hills around Siena came an iron-rich clay, terra di Siena, that produced a yellowish-brown pigment. Heated in a furnace, the clay yielded burnt sienna, which was reddish-brown. Raw umber, darker in tone, came from earth rich in manganese dioxide, while red ochre was manufactured from another variety of ruddy clay excavated among the Tuscan hills. Bianco Sangiovanni, or St John’s white, was a white pigment that came from Florence itself, and was named after the city’s patron saint. It was made from quicklime that had been slaked and then buried in a pit for several weeks until it turned into a thick paste that was then exposed to the sun to cake.
Other pigments came from further afield. Terra verde was manufactured from a greyish-green mineral (glauconite) quarried near Verona, a hundred miles to the north of Florence. A much more remote source provided ultramarine. As the name azzurro oltramarino indicates, ultramarine was a blue that came from ‘beyond the sea’, that is, from Afghanistan, where lapis lazuli was quarried. The Gesuati friars made this expensive pigment by grinding the blue stone in a bronze mortar, mixing it with waxes, resins and oils, then melting everything together in an earthenware pot. The pasty mixture would be wrapped in linen and kneaded like bread dough in a solution of warm lye. Once saturated with colour, the lye was poured into a glazed bowl, after which more lye was added to the squelchy mass, saturated with blue and emptied into a second bowl – and so on, until the mush no longer coloured the lye. The lye was then drained from each of the bowls, leaving the blue residue behind.
This method produced several grades of ultramarine. The largest and bluest particles came from the first press, after which grades of diminishing quality were collected. It was likely a blue from this first press that Michelangelo wanted when he asked Fra Jacopo di Francesco for a ‘certain amount of fine quality azure’. If so, the pigment would not have come cheaply. Ultramarine was almost as valuable as gold, costing as much as eight ducats per ounce – thirty times more than azurite, the next most expensive blue, and more than half the annual rent of a good-sized studio in Florence.11 Ultramarine was so valuable, in fact, that when Perugino frescoed the cloisters of San Giusto alle Mura, the prior insisted on being present whenever the pigment was used in case the artist should be tempted to pinch some. Perugino was an honest man, but the prior had good reason to safeguard his ultramarine, since unscrupulous artists would substitute azurite for ultramarine and pocket the difference in price, a fraud outlawed by the guilds in Florence, Siena and Perugia.
Ultramarine was almost always added a secco, that is, with the aid of a fixative once the intonaco had dried. There were precedents, however, for using ultramarine in buon fresco, most notably that of Ghirlandaio in the Tornabuoni Chapel. Michelangelo may have chosen his Florentine assistants, among other reasons, because as pupils of Ghirlandaio they were trained in the buon fresco application of bright colours like ultramarine. Still, he seems not to have used a great deal of ultramarine on the vault.12 This was no doubt partly for economic reasons, since he would later boast to Condivi that he spent no more than twenty or twenty-five ducats on pigments for the Sistine Chapel13 – barely enough to buy three ounces of ultramarine, let alone any of the other colours. Nor did he use very much, if any, of the other mineral-based pigments – azurite, vermilion, malachite – that were traditionally added a secco. Following their problems with mildew on The Flood, he and his assistants worked primarily in the more impregnable, but also more difficult, buon fresco style, albeit with occasional secco touches.14 Remarkably, the Ancestors of Christ would be painted almost exclusively in buon fresco.
Though small in size, the spandrels projecting above the windows on either side of The Flood were not easy to paint, offering curved, triangular surfaces on to which Michelangelo had to project his figures.15 Still, work seems to have progressed fairly swiftly. While The Flood consumed the better part of two months, the first two spandrels took only eight days each to paint.16 Michelangelo and his team transferred the cartoon for the first one, that on the north side, by means of a combination of spolvero and incision. Evidently growing more confident, for the one on the south side, whose nameplate reads IOSIAS IECHONIAS SALATHIEL,17 Michelangelo used spolvero to transfer the designs of the faces but then abandoned his cartoon altogether and painted freehand on the plaster. This was a bold move considering that mistakes made in painting The Flood had entailed removing the plaster and starting again. Yet it seems to have worked, since neither pentimenti nor secco touches were needed. A small scene that occupies an unobtrusive spot on the ceiling, this spandrel – which shows a trio of people slumped on the ground – nevertheless marks an important stage. After several months of work, Michelangelo finally seemed to be finding his feet.
With these two scenes completed, Michelangelo moved down a few steps on the scaffold to the level of the lunettes, always the last segments in these latitudinal bands to be painted. He found them much easier than the scenes on the vault fifteen or twenty feet above. Unlike these loftier panels, which forced him to bend over backwards and raise his brush above his head, the lunettes offered a flat, vertical surface. Painting the lunettes proved so simple, in fact, that he continued the unusual practice of dispensing with cartoons altogether and worked freehand on the plaster.
Not having to spend time preparing cartoons in the workshop and transferring them to the wall allowed Michelangelo to work much faster. The first lunette was dispatched in only three days: one giornata was spent on the square, gold-trimmed nameplate, a second on the figures to the left of the window, a third on those to the right. Given that the figures in this lunette are seven feet high, Michelangelo was working at a frantic pace, even by the rapid standards of fresco painting. And while the nameplates were executed by assistants using rulers and string, there is no doubt that all of the figures were painted by Michelangelo himself.
Eager to start work, Michelangelo sometimes began painting while the plaster was still too wet, abrading its surface with his paintbrush and tearing the fragile membrane on which the frescoist worked. Because the lime in the intonaco destroyed miniver brushes, which were made from the fur of squirrels or stoats, he almost always used brushes made from hogs’ bristles. Sometimes he worked so frenetically that bristles from his brush were left in the plaster.
On the lunettes, Michelangelo first sketched the outlines of the Ancestors on to the intonaco with a dark pigment on a narrow brush, making reference to small drawings executed earlier. Next, switching to a wider brush, he painted the backgrounds surrounding the Ancestors with a purplish-pink pigment known as morellone. This pigment, iron sesquioxide, was produced by combining vitriol with alum and then heating the mixture in an oven until it turned a light purple. It was a substance well known to alchemists, who called it caput mortuum, or ‘dead head’, their name for the residue left at the bottom of the beaker.
Having completed the background, Michelangelo returned to the figures themselves, using colour to shape them, starting with the shadows, moving on to the middle tones, then finishing with highlights. Frescoists were usually taught to charge their brushes with pigment, then squeeze the bristles between the thumb and index finger to rem
ove the excess water. But Michelangelo painted the lunettes with a wet brush, applying colour in such thin, watery coats that in places he created a translucent effect akin to watercolour.
Bright yellows, pinks, plums, reds, oranges and greens – Michelangelo charged his brush with the brightest colours in the frescoist’s palette as he painted the spandrels and lunettes, using them in startling combinations that in places imitated the effect of shot silk. One of the spandrels beneath The Flood, for example, shows an orange-haired woman in a shimmering pink-and-orange dress sitting beside her elderly husband, who sports a robe of brilliant scarlet. The full tone of these dazzling colours has only recently been rediscovered. Layers of unsaturated fat from five hundred years’ worth of candles and oil lamps, together with thick layers of glue and linseed-oil varnishes slathered across the fresco during multiple incompetent restorations, served to give the spandrels and lunettes such a sombre and muddied appearance that in 1945 the greatest Michelangelo scholar of the twentieth century, the Hungarian-born Charles de Tolnay, christened them ‘the Sphere of Shadow and Death’.18 Only when more expert conservation work undertaken by the Vatican in the 1980s stripped these layers of grime from the surface of the fresco did Michelangelo’s true colours reveal themselves.