The artist’s fingers: The secret of 18th-century brushes

In the 18th century, a brush was not something bought ready-made from a shop. It was an extension of the artist’s hand, shaped with the same care as a violin for a musician. Each master had their secrets: the length of the bristles, the type of glue, the shape of the ferrule. These details, now forgotten, made the difference between a stroke of genius and an awkward line. What if we lifted the veil on these vanished gestures, to understand how a simple tool could give birth to masterpieces?

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The studio as laboratory: when the artist becomes craftsman

In the narrow streets of Paris or Venice, painters’ studios resembled alchemists’ laboratories. There were pots of pigments, marble mortars, vials of linseed oil—and, of course, piles of animal hairs, meticulously sorted. For making a brush was as much a science as an art. Apprentices spent hours washing the hairs in soapy water, smoothing them with ash, aligning them one by one like the strings of an instrument. A poor sort, and the brush lost its suppleness; a badly measured glue, and the bristles fell out at the first stroke.

Take François Boucher, for example. For his rosy nudes and silken draperies, he used badger-hair brushes, prized for their softness and their ability to hold paint. But these hairs were not easy to come by: they came from badgers hunted in the forests of northern Europe, and their preparation demanded infinite patience. Boucher soaked them in linseed oil for days before mounting them, so they would keep their elasticity. The result? Strokes so fluid they seem to flow across the canvas, as in The Toilet of Venus, where every fold of the gown appears caressed by an invisible breeze.

At the other end of the spectrum, Jean-Siméon Chardin preferred hog bristles, stiffer, for his still lifes. These brushes, which he made himself, allowed him to layer paint with surgical precision. Look at The Olive Jar: the texture of the porcelain, the reflection of light on the glass, the deep shadows of the fruit—all this was made possible by brushes capable of laying down paint thickly, without smudging. Chardin often said that "painting is something you touch as much as you see." His brushes were proof of that.

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The hunt for hair: a quest worthy of great explorers

Behind every brush lay a story of trade, travel, and sometimes even espionage. The best hairs came from far away: the Siberian kolinsky sable, the badger from Scandinavian forests, the squirrel from the Swiss mountains. Artists depended on merchants who crisscrossed Europe to bring back these treasures, often at a king’s ransom. A sable brush could cost the equivalent of a month’s rent for a Parisian craftsman.

Watteau, always on the lookout for new techniques, had befriended a Venetian merchant who supplied him with "special" sable hairs, supposedly treated according to a secret method. These hairs, more supple and resilient than others, allowed him to create the translucent effects that give his fêtes galantes their magic. But this dependence on exotic materials came at a price: in 1719, a shortage of Siberian sable nearly paralyzed his work. He had to improvise with polecat hairs, cheaper but less reliable, and his last works bear the mark—strokes a little more hesitant, as if the brush refused to obey.

English artists had their own suppliers. Thomas Gainsborough, who painted landscapes in vaporous tones, used squirrel-hair brushes imported from Russia. These hairs, longer and softer than sable, allowed him to blend colors with unmatched delicacy. But again, quality came at a cost: Gainsborough spent fortunes on brushes, to the point that his patrons complained. One day, one of them asked why he didn’t settle for ordinary brushes. His answer? "A violinist wouldn’t play on a shoddy instrument. Why should a painter?"

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The secret of ferrules: when metal becomes magic

If the hairs were the heart of the brush, the ferrule was its soul. This metal ring, which held the bristles in place, was far more than a simple accessory: its shape, thickness, and material determined the precision of the stroke. 18th-century artists knew this well, and they chose their ferrules with as much care as their pigments.

Brass ferrules, for example, were prized for their durability. Jacques-Louis David, who painted draperies with geometric folds in The Oath of the Horatii, used brushes with thick ferrules, capable of withstanding the pressure of his firm strokes. Watteau, on the other hand, preferred thin, almost fragile ferrules, which allowed him to vary the pressure for wider or narrower lines. One day, a visitor to his studio marveled at the delicacy of his tools. Watteau replied with a smile: "A brush must be like a bird’s feather—strong enough to fly, light enough not to weigh down the wing."

But ferrules weren’t always made of metal. In modest studios, rings of goose quill or wood were used, cheaper but less durable. These "poor" brushes were often reserved for sketches or backgrounds, while quality tools were used for details. A hierarchy thus emerged in the studio, mirroring that of society: masters worked with silver or ivory ferrules, while apprentices made do with more rudimentary versions.

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Glue and mystery: when chemistry comes into play

Behind the making of a brush lay another science, quieter but just as crucial: that of glue. Without it, the hairs would fall out, and the brush would be useless. 18th-century artists had their secret recipes, passed from master to pupil like alchemical formulas.

Rabbit-skin glue was the most common. Made by boiling skins in water, it was strong and flexible. But it had one drawback: it attracted insects. To ward off this scourge, some artists added garlic or vinegar to their mixture—a trick said to come from Rembrandt. Others preferred fish glue, more resilient but harder to prepare. Chardin, ever meticulous, used a glue made from pig bladders, which he simmered for hours to achieve the perfect texture.

But glue wasn’t just about strength. It also influenced how the brush behaved. Glue that was too thick made the bristles stiff; glue that was too thin made them sag. Masters spent hours adjusting their recipes, testing each new version on practice canvases. One day, a student of David’s asked why he devoted so much time to this step. The master replied: "A poorly glued brush is like a soldier without armor. It may hold for a while, but it will eventually fall."

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The brushes that made history: when the tool becomes legend

Some brushes have crossed the centuries, becoming almost sacred relics. Watteau’s, for example, was preserved by his friend the engraver Jean de Jullienne, who considered it a talisman. Today, it rests in the reserves of the Louvre, its sable hairs still supple despite the three hundred years since their maker. Experts who have examined it were astonished: despite its age, it retains remarkable elasticity, as if waiting for the next stroke.

Other brushes have had more eventful fates. David’s, for instance, were scattered after his death, some sold at auction, others passed on to his students. One of them, a short, thick brush used for The Death of Marat, was found in the 1950s in a Parisian antique shop. It still bore traces of red paint—the revolutionary’s blood, frozen in time.

But perhaps the most fascinating is Gainsborough’s brush, kept at the Victoria & Albert Museum. Made with squirrel hairs and a silver ferrule, it was used to paint some of the most beautiful landscapes in English art. In 2015, an X-ray analysis revealed a surprising detail: the ferrule contained traces of gold. Gainsborough, ever the perfectionist, had gilded the inside of his brush so the hairs would glide better. A devotion to detail that speaks volumes about his obsession with quality.

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The lost legacy: why these gestures disappeared

With the Industrial Revolution, everything changed. In the 19th century, brushes became standardized products, mass-produced in factories. Artists stopped making them themselves, preferring to buy them from merchants like Lefranc or Winsor & Newton. This evolution democratized access to art, but it also erased a unique know-how.

Yet some contemporary artists are trying to revive these techniques. The German painter Marlene Dumas, for instance, still uses sable brushes, which she prepares herself according to old methods. "An industrial brush can’t convey the same emotion as a handmade tool," she explains. "It’s like comparing a Stradivarius to a factory-made instrument."

Others, like Julie Mehretu, experiment with hybrid brushes, mixing natural hairs and synthetic fibers. But the gesture remains the same: that of an artist seeking to master the material, to coax emotion from a single stroke. Perhaps this is the most valuable lesson of the 18th century: a brush is not just a tool. It is a bridge between hand and soul, between technique and genius. And today, when a painter dips their brush into paint, they unknowingly perpetuate a ritual three hundred years old.