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How Prussian blue changed everything

Born in a chemical accident in a Berlin laboratory, the highly coveted pigment has inspired some of the greatest art in history, from Turner’s seascapes to Hokusai’s waves and the paintings of Picasso’s Blue Period. By Holly Black

Discovered in the early 18th century, Prussian Blue revolutionised an art industry starved of a stable blue pigment to rival the prohibitively expensive ultramarine.

The creation of Prussian blue was the result of a simple error by two German alchemists, Jacob Diesbach and Johann Konrad Dippel. While mixing a batch of cochineal red, Diesbach was alarmed to discover that his concoction had turned a deep blue. After much investigation, he determined that this was the result of a chemical reaction caused by animal blood found in contaminated potash provided by Dippel. The world’s first synthetic pigment was born. 

In the art world, the introduction of Prussian blue ‘had a real impact’, says Kassia St Clair, author of The Secret Lives of Colour. The high price of ultramarine — produced by grinding down lapis lazuli mined from the mountains of Afghanistan — meant that blue was generally reserved for religious pictures, particularly depictions of the Virgin Mary. ‘There’s an irony in the fact that Prussian blue was tainted with blood and discovered by a couple of charlatans,’ says St Clair. ‘Suddenly the meaning of colours and the importance attached to them changed.’

Jean-Antoine Watteau’s Pilgrimage to Cythera  from 1717 is one of the earliest known paintings in which Prussian blue was used. Photo Louvre, Paris, France  Bridgeman Images

Jean-Antoine Watteau’s Pilgrimage to Cythera  from 1717 is one of the earliest known paintings in which Prussian blue was used. Photo: Louvre, Paris, France / Bridgeman Images

Non-toxic, affordable and stable, the new blue spread rapidly throughout Europe, its dense tint making it ideal for rich Rococo scenes. Prussian blue is present in Antoine Watteau’s 1717 painting Pilgrimage to Cythera, ‘one of the earliest known appearances of the pigment,’ says Alan Wintermute, Old Masters and Early British Painting specialist at Christie’s in New York. Recent analysis of works in the Louvre by Watteau’s principal followers Jean-Baptiste Pater and Nicolas Lancret reveal its presence in their paintings from the 1720s, Wintermute adds.

‘Picasso used Prussian blue to cast a melancholy shade on his works. Many view the Blue Period as a pivotal moment in his artistic journey’ — Allegra Bettini

The popularity of Prussian blue hadn’t waned by the time J.M.W. Turner began painting his turbulent seascapes in the late 18th century. According to Annabel Kishor, specialist in British Drawings and Watercolours at Christie’s in London, Turner ‘was extremely experimental when it came to pigments. He was using more than 30 different varieties when many of his peers were only using eight or nine.’

Thomas Gainsborough, Mr and Mrs Andrews, circa 1748-49. Photo National Gallery, London, UK  Bridgeman Images
Thomas Gainsborough, Mr and Mrs Andrews, circa 1748-49. Photo: National Gallery, London, UK / Bridgeman Images

Prussian blue was not a perfect pigment, however: concerns about discolouration were raised soon after it came into production. ‘Prussian blue has a high tint power,’ explains Michael Harding, a master paint-maker and an expert on oil paints. Because of this, an artist would ‘need to use only a minute amount when painting a sky, for example.’ Diluting a pigment in this way ‘makes it much more vulnerable to UV light.’ 

Discolouration has been identified in the paintings of Thomas Gainsborough, another great fan of Prussian blue. ‘Restoration was undertaken on Gainsborough’s Mr and Mrs Andrews  by the National Gallery,’ says Harding. ‘When they removed the frame it was clear that there had been a lot of fading.’ 

Still, Prussian blue remained one of the most durable pigments on the market, with most artists being willing to forgo the risk in order to achieve the cool intensity it offered. Its popularity was such that it even permeated Japan’s closed borders, proving a major inspiration for Katsushika Hokusai. In his iconic seascape The Great Wave off Kanagawa, the artist mixed it with traditional indigo to produce subtle gradations in the roaring waters.

‘I supplied Damien Hirst with 29 litres of Prussian blue some years ago, enough to paint a battleship. I don’t know what he ended up using it for’ — Michael Harding

Many artists turned to Prussian blue to convey deeper emotions. In works painted between 1901 and 1904 — his so-called ‘Blue Period’ — Pablo Picasso used Prussian blue, in addition to green and grey pigments, ‘to cast a melancholy shade on his works,’ says Christie’s Impressionist and Modern Art specialist Allegra Bettini. ‘Many view this period, in which he began to set himself apart from his contemporaries, as a pivotal moment in Picasso’s artistic journey.’   

The distinct qualities of Prussian blue make it particularly attractive for an artist looking to work in a restricted chromatic palette without sacrificing intensity. ‘It’s a very roomy colour,’ explains Kassia St Clair. ‘You can use it as a glaze over other colours, and it is generally very versatile.’

For Harding, Prussian blue is one of the most intense pigments an artist can use: ‘If you don’t know how to handle it, the colour will creep into just about everything on your palette. It can be like painting with a nuclear weapon,’ he says.

Harding continues to see a hunger for the pigment in the contemporary market, despite a greater variety of alternatives. ‘I supplied Damien Hirst with 29 litres of Prussian blue some years ago — enough to paint a battleship. I don’t know what he ended up using it for. It’s a puzzle because if you’re taking 29 litres of Prussian blue you’re going to want more of other colours, too, but he didn’t.’

Harding notes that there is great demand for the colour in other sectors as well: industrial printers around the world ‘use several thousands of tonnes a year,’ he says. ‘Without that need, it would be much harder for specialists like me to get hold of it.’

Other uses of the pigment have been revolutionary in their own right. Appreciating its light-sensitive properties, 19th century astronomer John Herschel used Prussian blue to produce the world’s first blueprints, enabling the simple and effective reproduction of diagrams and plans. Also in the 19th century, Anna Atkins, arguably the first recognised female photographer, used the pigment to create her groundbreaking plant cyanotypes. 

Today it is even used as a chemical treatment for radiation poisoning — demonstrating that the power of Prussian blue extends well beyond the art world.