Painters obsess over pigments, and sometimes they become the downfall of their work.
Before it could be made artificially, ultramarine cost more than gold, and was often the major determinant of the cost of a painting. But for all its cost, ultramarine has proved to be one of the most reliable of natural pigments. Indian yellow is more of a mystery: while used in Asian painting, particularly that of the Indian sub-continent, it was claimed to be extracted from the urine of cattle fed on a diet of mango leaves. It too sold for high prices in Europe, and was officially outlawed at the end of the nineteenth century for cruelty to animals.
Mummy is even more dubious: originally claimed to be extracted from the ground bodies of embalmed Egyptians, thankfully much of it appears to have different origins. Its source and composition appear to have changed over time, and at some periods it may well have contained significant amounts of asphalt, widely ranked as the most deadly and destructive of them all.
Asphalt isn’t even a true pigment, but an odd colloid cocktail of organic and inorganic materials. Some, such as the viscous binder within asphalt known as bitumen, are organic residues, others can include modified vegetable matter, mineral particles, and more. Asphalt and its derivatives also go under a variety of names, including Antwerp brown, and sometimes mummy.
Asphalt has been used in oil paint, and in varnishes; being strongly hydrophobic it’s almost impossible to incorporate into watercolour. It isn’t the ‘blackest black’ as has sometimes been claimed, but a very deep brown-black, and was apparently prized by many artists.
Notorious for the problems in the paint layer it can be associated with, asphalt has been blamed for bleeding, discolouration, wrinkling, cracking and eventual destruction of paintings. But careful examination of paintings known to contain it suggests those aren’t necessarily the consequences of using asphalt: genuine asphalt has been used in some old paintings without any ill-effects.
Orazio Gentileschi’s Joseph and Potiphar’s Wife painted in 1626-30 is one of the few paintings known to contain asphalt in its paint layer, yet appears in remarkably good condition considering that it’s almost four hundred years old.
One major work in which there seems to be extensive written evidence of the use of asphalt is Théodore Géricault’s The Raft of the Medusa (1818-19). However, critical examination of sources shows that they depend on a single original document, a note made on an unspecified date by Géricault’s assistant Jamar, who listed the pigments used by the Master as: “vermillon, blanc, jaune de Naples, ocre jaune, terre d’Italie, ocre de Brie, terre de Sienne naturelle, brun rouge, terre de Sienne brûlée, laque ordinaire, bleu de Prusse, noir de pêche, noir d’ivoire, terre de Cassel, bitume.”
Cassel earth is a derivative of lignin rather than asphalt, but readily confused with asphalt as they have similar colour. Géricault is also alleged to have used asphalt glazes or varnishes late in the painting process, but at that stage few reliable witnesses were given access to his studio.
The Raft of the Medusa may well have undergone varnishing with asphalt, and is the worse for wear considering that it’s only two hundred years old. However, its life has been stressful in more physical ways: it remained unsold after it was first exhibited at the Salon in 1819, so was rolled up and stored in a friend’s studio, until it was transported to London, still rolled up, for exhibition the following year.
There are also claims made for several of JMW Turner’s paintings that they contain asphalt in the paint layer, causing their deterioration. I’m not aware of any robust analyses that have confirmed the pigment’s presence, though.
Turner’s Fighting Temeraire has areas in which wrinkling is apparent, probably resulting from the slumping of impasto, and exudation of undried paint. This has been attributed to Turner’s presumed use of asphalt, which can inhibit the oxidative drying of linseed oil.
The Rape of Proserpine (1839) also has its problems. Here Turner worked freely, mixing layers of low to medium impasto with thinner glazes and scumbles, particularly in the sky. Although cracking has occurred, this hasn’t resulted in significant loss of the paint layer.
It has been proposed that problems in the foreground and middleground of Turner’s Rape of Proserpine are the result of his use of asphalt. Cracks here have widened, and become filled with paint that has risen from deeper layers.
Many of the paintings of the American artist Albert Pinkham Ryder (1847–1917) have suffered severe problems in the paint layer, and some are now almost completely lost as a result. Ryder was known to have incorporated a wide range of unconventional materials and substances in his paintings, which are thought to have included asphalt. Unfortunately, there doesn’t appear to be robust analytical evidence demonstrating the presence of asphalt.
The Waste of Waters is Their Field (c 1883) is a small oil painting now almost completely lost, with much of the detail merged into a dark brown mess as its superficial layers have faded, and the deeper layers darkened. The detail below shows that its entire paint layer is dissected by cracks, many of them gaping and oozing lighter wet paint from below.
Details can still be made out in his tiny Resurrection (1885), although even this has changed and cracked severely. Many of the cracks are wide and filled with paint that has risen up from lower layers.
The objective evidence shows that it’s possible for paintings containing asphalt to live long and strong, but its rumoured use has been claimed to result in destruction of the paint layer. Perhaps it’s as well that asphalt and its relatives became unfashionable in the nineteenth century, and are almost unobtainable in oil paints today.
This didn’t end the use of suspect pigments, though. From the late 1950s, Yves Klein made monochrome paintings using synthetic ultramarine pigment in a synthetic resin, a combination he branded International Klein Blue. The resin turns out to be a polyvinyl acetate (PVA), widely used as wood glue. Despite his untimely death at the age of only 34, he’s now considered “an important figure in post-war European art” (Wikipedia) for his use of one of the oldest pigments in European art.
References
Géricault’s Raft of the Medusa, a detailed analysis of the evidence of its making.
Catarina I Bothe (2007) Artists’ Pigments, vol 4, ed Barbara H Berrie, Archetype. ISBN 978 1 904982 23 4.