The grid he never painted over

Here is the secret hiding in plain sight, and it is the reason this particular version of The Third-Class Carriage is the famous one: it is unfinished. Daumier started it and stopped — left it abandoned, the paint thin in places, whole passages barely worked up, the dark only roughed in. Normally an unfinished painting is just a sad fragment, a thing the artist would not have wanted you to see. But this one is unfinished in a way that turns into a gift, because Daumier was caught mid-process, and the canvas froze with all of his scaffolding still showing. You are looking at a picture you can see through — down to the bones of how it was made.

Lean in on the unfinished areas, especially up near the two windows at the left, and you will see something most paintings hide forever: straight ruled lines, a faint grid of squares, and the bare drawn contours of the figures, showing right through the thin oil. That grid is not damage and it is not decoration. It is the machinery of the painting, left bare because the paint that was supposed to cover it never arrived.

To understand what you are seeing, you need one technique, and it is a beautifully simple one that artists have used for centuries. Suppose you have a small drawing or watercolor you love, and you want to copy it accurately onto a much bigger canvas — bigger than you can just eyeball. You draw a grid of squares over the small version, and then you draw a matching grid — same number of squares, scaled up — onto the big canvas. Now you copy the picture one square at a time: whatever is in the little square here goes into the big square there. The grid keeps everything in proportion as you enlarge it. This is called squaring up, or squaring for transfer, and the grid is supposed to be the first thing you draw and the last thing you think about — you paint right over it and it disappears.

On the Met’s canvas, it never disappeared. The painting is, in the museum’s own words, “still squared for transfer” — Daumier had ruled his grid, drawn his figures square by square, begun laying in the paint, and then put it down before the surface was finished. So the grid is still there, faint but unmistakable, a ghost of straight lines under the people. He was almost certainly enlarging from a smaller study — most likely a watercolor of the same scene (more on that in a moment) — and we have caught him with the enlargement only half-done.

Think about how rare this is. A finished painting is a sealed object; it shows you the result and hides the labor. To see how an old master actually built a picture, museums normally have to shoot it with X-raysor infrared cameras to peer beneath the top layer at the drawing underneath. Here you need no machine. Daumier’s abandoned canvas is, in effect, a free X-ray — the underdrawing and the grid sitting right on the surface where anyone can read them. You can watch a great picture in the act of being made: the ruled scaffolding, the drawn search for each figure, the paint beginning to climb over the drawing in the most worked passages (the old woman’s face) and not yet arriving in the least (the dark back of the car).

And here is the irony that makes art historians smile: this is exactly the version everyone reproduces. A perfectly finished Third-Class Carriage exists — it would have buried its grid like every other painting — but it is the broken, half-built one that became iconic, precisely because it is broken. The unfinish is not a defect to apologize for; it is the most interesting thing in the room. The painting lets you see Daumier thinking.

That smaller study the grid points back to is real, and it opens up an honest complication worth knowing: there is no single The Third-Class Carriage. Daumier worked the subject more than once. There is a finished oil painting in the National Gallery of Canada, in Ottawa, very close in composition to this one. There is a watercolor of 1864 in the Walters Art Museum in Baltimore — commissioned by the American collector William T. Walters (the Baltimore businessman whose private collection later became that museum) as part of a set showing first-, second-, and third-class carriages — and the squaring grid on the Met’s canvas may well have been taken straight off it. There is an even earlier oil on a wooden panel in San Francisco, with the three main figures arranged differently. He kept returning to the cheap seats, in print and in paint, for the better part of two decades.

So the honest way to say it is this: the Met owns one member of a family — the unfinished one, the one whose machinery shows. It is not the “original” and the others “copies”; it is one pass at a subject Daumier could not leave alone. And it became the most beloved of them all by an accident of incompletion — because the version where the paint stops short is the version where you can see, with your own eye and no apparatus at all, exactly how a man builds a picture of the poor.