What is a pentimento?

Look closely at an old oil painting and you’ll sometimes find a ghost. A second outline of an arm. A hat that seems to have been in two places at once. A faint shape in the sky that doesn’t belong to anything.

That ghost is a pentimento. The word comes from the Italian pentirsi, to repent or change your mind, and it means a change the painter made while working: something painted, then painted over. The plural is pentimenti. Lillian Hellman borrowed the word for her 1973 memoir, Pentimento: A Book of Portraits, and one chapter of it became the film Julia.

Why the past shows through

Oil paint isn’t as solid as it looks. Over decades and centuries some paint grows more transparent, and what was hidden underneath begins to come back. The painter who covered it never meant you to see it. Time decided otherwise.

Some pentimenti have been faintly visible from the start. Others take centuries to surface. And some never come through at all, and wait for someone to go looking.

Second thoughts

Velázquez’s portrait of King Philip IV of Spain, in the Frick Collection in New York, is full of them. When conservators studied it, they found he had first painted the king’s hat lower, given the coat a wider, flared outline and had the sword a little higher. Some of those changes can be seen with the naked eye. You can stand in front of the painting and watch one of the greatest painters who ever lived change his mind.

Rembrandt changed the hat in Flora, his painting from 1654. Caravaggio moved one of the figures in The Cardsharps. None of this is a flaw. It’s what thinking looks like when it’s done in paint.

How to find one yourself

You don’t need an X-ray to start looking. Next time you’re in a gallery, look at the edges of things: the outline of a hat, a shoulder, a hand, the line where a figure meets a dark background. A pentimento often shows as a faint second edge, the ghost of a shape that was there first, a little lighter or darker than the paint around it.

Then stand to one side, so the light skims across the surface instead of hitting it straight on. Paint that was built up for something and then covered can leave a ridge or a change in texture, even when the colour gives nothing away. Conservators do the same with a lamp held low to the side, which they call raking light.

Once you start seeing them, it’s hard to stop.

Reading under the surface

Conservators don’t have to wait for time. X-rays pass through paint but are stopped by heavy pigments such as lead white, so they show what’s been laid down in the lower layers. Infrared passes through many paints and picks up the drawing beneath. A painting can be read in layers, like a letter that has been written over.

Sometimes what turns up is more than a change of mind. Picasso’s The Old Guitarist, in the Art Institute of Chicago, shows an old man bent over his guitar. X-rays and infrared images have found other figures beneath him: an old woman with her head bowed, a young mother with a small child kneeling beside her, and an animal.

Picasso’s The Blue Room, painted in 1901 and now in the Phillips Collection in Washington, shows a woman bathing. A conservator noticed in 1954 that the brushstrokes didn’t match the picture. In 2008, infrared imaging found a man underneath: bearded, wearing a jacket and bow tie, his face resting on his hand, with three rings on his fingers. Nobody knows for certain who he is.

The reason was money. In 1901 Picasso was nineteen, living in Paris and short of it. He couldn’t afford a new canvas every time he had an idea, so he painted over old ones. Not a change of mind. A whole other picture, lost under the one he chose to keep.

What a change of mind gives away

Here is the part that matters to people who authenticate paintings.

A copyist reproduces what they can see. A forger does the same, and works hard not to make mistakes. Neither of them has any reason to paint an arm in one place and then move it, because they already know where the arm goes. So a pentimento, a real one, buried under the surface, is evidence that the picture was being worked out as it was painted. That suggests the first version, by the artist, rather than a copy.

It has been used in some very expensive arguments. When Salvator Mundi was attributed to Leonardo da Vinci, one of the points made in its favour was a pentimento: Christ’s right thumb had first been painted in a different position. In 2017 it sold for more than $450 million. Its attribution is still argued over.

The Courtauld Gallery in London owns a version of Manet’s Le Déjeuner sur l’herbe. For a long time it was thought to be a copy. Its pentimenti helped persuade experts that it was something else: Manet’s own preparatory painting.

That’s the strange power of a pentimento. It’s a mistake, and the mistake is what proves it’s real.

A change of mind, or a cover-up

A pentimento is the painter’s own change. Sometimes the change was made by somebody else.

For centuries, Vermeer’s Girl Reading a Letter at an Open Window, in Dresden, showed a young woman reading by a window in front of a bare wall. An X-ray in 1979 found a painting of Cupid hidden on that wall, and for years it was thought Vermeer had painted him out himself. Then a restoration that began in 2017 showed the overpaint had gone on long after Vermeer’s death, by another hand. The museum removed it, and since 2021 Cupid has been back on the wall.

Sometimes the cover-up was official. In January 1564, after the Council of Trent had condemned nudity in religious art, Pope Pius IV ordered the nudes in Michelangelo’s Last Judgment in the Sistine Chapel to be covered. The painter Daniele da Volterra was given the job of adding the drapery, and for it he earned the nickname Il Braghettone: the breeches-maker.

That’s the difference. One is a painter thinking. The other is someone deciding what you’re allowed to see.

Underpainting

There’s one more layer, the first one.

An underpainting is the base a painter lays down before anything else, often in a single colour. A plain grey one is called a grisaille. Italian painters often used a greenish grey, verdaccio, under skin, to make the flesh tones above it glow. The underpainting fixes where the light and shadow will fall, and then it’s meant to disappear under everything that follows. It’s there in the finished picture. You’re just not supposed to see it.

Why the books are called what they’re called

Dr Alec Muir, at the centre of Pentimento, authenticates paintings. He has spent his life looking for the changes of mind under a surface. Nobody in Scotland is better at seeing what lies beneath. And nobody has worked harder to keep anyone from looking beneath his. The book takes the word at its meaning: the past doesn’t stay buried. It shows through.

Underpainting, the second book, takes the other word. In it, a woman clearing her late father’s house in Milngavie takes down the portrait that has hung on his stairs all her life, the grey lady, and starts asking who she was.

Beneath the grey lady is another woman. Someone has spent a very long time making sure nobody saw her.