T hink of Impressionism and our minds turn to light. We marvel at the evaporative splendour of Claude Monet’s weightless water lilies and how Georges Seurat succeeded in sieving sunsets down to a dazzle of shimmering dots. Whether we think first of the glistering shadows of Camille Pissarro’s immaculate snowscapes or of the restless radiance of Pierre-Auguste Renoir’s rippling rivers, Impressionism is synonymous with ethereal epiphanies – of fleeting flashes of light eternally suspended.
But in great art, nothing is ever what it seems. Behind the language of lilting light that the Impressionists first unveiled at the inaugural exhibition of their work in Paris in April 1874, an alluring lexicon that would evolve as the movement mutated in the ensuing years into Neo-Impressionism and Post-Impressionism, is something surprisingly rough and gritty, hefty and material: colour. To create the illusion of levitating luminosity that characterises the surface resplendence of works by everyone from Alfred Sisley to Paul Cézanne, Berthe Morisot to Edgar Degas, these pioneering artists relied on a clutch of paradoxically grubby pigments – some ancient, some new – whose murky materiality is at furthest remove from the evanescence that continues to seduce our eye to this day. These pigments, from prehistoric bone black to cutting-edge cobalt violet, lethal lead white to newfangled chrome orange, bring with them contrary counter-narratives of their own – extraordinary backstories of toxic concoction by forgotten alchemists and serendipitous discovery by savvy entrepreneurs, that unsettle and invigorate the meaning of the works they describe.
"These pigments, from prehistoric bone black to cutting-edge cobalt violet, lethal lead white to newfangled chrome orange, bring with them contrary counter-narratives of their own."
Exemplary of this tension between the sublime light vibrating from a painting and the harsh substances that coax it from the canvas is Paul Signac’s eerily absorbing Saint-Tropez Le rayon vert, which the Paris-born artist, and erstwhile pioneer (along with Seurat) of Pointillism, created in 1906. The work captures an arresting moment when the embering sky at sunset dappling a bay in the south of France is suddenly slashed, severed by the relatively rare meteorological phenomenon known as a ‘green ray’ – an exhilarating flash of verdigris light that the earth’s atmosphere at sundown prises loose from the prism of dusklight.
It lasts no longer than a second or two at most. A master of luminous form and formal luminosity, Signac not only freezes the flash, he manages to translate the ephemeral refraction into something at once solid and frangible, transitory and transcendent – a glittering metaphor of our own inevitable dispersal into bright nothingness.
It somehow seems fitting that the colour Signac should reach for in order to sculpt this intangible emblem of our own brief flare into being is ‘emerald green’, a relatively new pigment discovered in 1814 coincidentally in both Bavaria and in Vienna by separate teams of entrepreneurs independently tinkering with proportions of verdigris (an ancient copper acetate), vinegar, sodium carbonate, and the highly toxic compound white arsenic.
Emerald green is a close cousin of so-called Scheele’s Green (named after the German-Swedish pharmaceutical chemist Carl Wilhelm Scheele who invented the colour in 1775) – a once-fashionable hue whose use in domestic paints and nursery wallpaper was eventually abandoned when its arsenic-laced fumes were revealed to be poisonous. That the inspiriting flash of otherworldly light that ignites Signac’s smouldering sky should be spiked with such sinister associations is both surprising and in accord with the complexity of a work that pulses with an awareness of life’s fragility and impermanence.
If that ominous glow rings a bell in the ear of your eye, you no doubt are hearing echoes from Van Gogh, who routinely returned to emerald green to inflect everything from the spectral trees through which his lovers slalom in Landscape with couple walking and crescent moon, to the quivering corona of the moon itself which troubles the corner of The Starry Night (both painted in 1889). Intensifying the edginess of the latter sky’s gloam is Van Gogh’s decision to construct the mustard moon from a pigment whose past remains murky and mysterious to this day: Indian yellow. According to legend (corroborated by forensic analysis of samples undertaken in 2019), this blistering butterscotch hue was derived from dehydrated clumps of urine collected from cows fed a diet consisting solely of mango leaves and water. Seen in such unsettling light, the psychological unrest of Van Gogh’s turbulent nightscape is subliminally amplified by traces of physical distress.
Everywhere we turn in Impressionism, the lyricism of light is haunted and enhanced by the ghosts of colour. Consider, for instance, the crisp radiance of Paul Cézanne’s Chestnut Trees at Jas De Bouffan, which captures an avenue of winter-whittled trees on his family’s estate in Aix-en-Provence in 1885. Bright bristles of green grass that dominate the foreground and the glimpses we have of a distant tree beginning to burst with fresh shoots near the centre of the canvas vibrate with the promise of spring’s imminent return.
Confounding that reassurance, however, framing it in a shatter of dark mullions, are the sombre skeletons of the chestnut trees themselves, whose leafless limbs Cézanne has accented with an ancient pigment, ‘bone black’. Among our oldest pigments, bone black can be traced back to prehistoric cave drawings, where it was derived from the pulverised remains of incinerated skeletons. Look again at Cézanne's work and the beautiful briskness of its light is emboldened, not embattled, by the deft dabs of scorched darkness that riddle the canvas and our eyes.
The Impressionists were not only adept at reinventing age-old pigments, they ingeniously deployed fresh hues that they were among the first artists to squeeze onto their palettes. Renoir, Manet, and Monet, respectively, employed the relatively new pigments of chrome orange, cobalt blue, and cobalt violet to powerful effect and in ways that would define the art of the era. According to the influential theory of colour contrasts that the French chemist Michel Eugène Chevreul proposed in 1837, ideas that significantly shaped the mindset of many of the Impressionists, orange (best paired with blue) was one colour that should be used sparingly, if at all.
But recent discoveries near Paris and near Baltimore, Maryland, of vast subterranean deposits of the crystalline mineral chromite, which suddenly made producing chrome orange feasible, proved irresistible to artists who had previously been unable to afford orange pigments – historically among the most expensive colours in the artist’s box. Boldly inflecting the outsized row boat in his painting La Yole (The Skiff) out of flaming chrome orange, Renoir ignites the centre of his canvas, as if giving us a glimpse into a fiery fissure – a deep deposit to which some part of our soul is desperate to ferry. The result is a painting emblematic of the Impressionist imagination, a work whose exquisite luminance is leant an unexpected density by the irrepressible gravities of colour.