At the Moulin Rouge, cut and rejoined

You are Henri de Toulouse-Lautrec, born at Albi in 1864. As a boy you are encouraged by the animal painters René Princeteau and John Lewis Brown.

In 1882 you enter Léon Bonnat's studio in Paris. He is said to have found your painting not bad and your drawing atrocious. You move on to Fernand Cormon's studio, where you meet Vincent van Gogh.

Rich, writing for the Art Institute in 1949, saw Degas's tilted views behind your compositions, and the big close-up heads of Japanese actor prints. At seventeen you wrote that you were trying to draw what was real, not ideal.

The Moulin Rouge opens in Montmartre in 1889, built for electric light. You become a regular with a table of your own, and its owner buys your Equestrienne to hang in the lobby.

In 1890 you paint its dance floor. In 1891 your first poster, Moulin Rouge: La Goulue, goes up on the walls of Paris and makes your name.

The dancers La Goulue, La Macarona and Jane Avril, the photographer Paul Sescau, the writer Édouard Dujardin: the hall's regulars are your friends and your sitters.

Set the viewer's eye level with Guibert's profile, so you look up under the brims of the hats. Cut off the corner with the diagonal rail, and let a face at the right edge be sliced by the frame.

• At the table, from the left: Édouard Dujardin, poet and critic; La Macarona, a dancer; Paul Sescau, photographer; Maurice Guibert. These are Joyant's names.
• With her back to you, red hair piled up: Jane Avril, according to Heller and the museum. Joyant did not name her, and Rich called her unidentified.
• Behind them, two dancers, one fixing her hair: La Goulue and, for Heller, La Môme Fromage. Accounts differ on which is which.
• Walking past at the back: you and your cousin, Dr Gabriel Tapié de Céleyran.
• At the right edge: “Mlle Nelly C.” for Joyant; May Milton since the museum's 1979 catalogue.

Heller traced La Macarona's white, powdered face to your portrait of her as a jockey, published in Le Figaro illustré in February 1894: you changed the costume and kept the face.

From 1890 to 1894 you almost stop painting on canvas. You work on cardboard in oil thinned with turpentine, sometimes with gouache or crayon, drawing in the thinned paint with great sureness, as Coquiot remembered.

For this picture you go back to canvas, but to a canvas primed with gesso tinted the colour of cardboard. That brownish tone is the base colour of much of the picture, and you thin your paint until it soaks into the ground. Heller noted the same tinted gesso on other canvases of 1894–96, such as The Salon in the Rue des Moulins, and suggested that painting the big canvases for La Goulue's fairground booth in 1895 brought you back to canvas.

Your lithographs shape the painting too: contour lines and large flat areas of colour. Heller called it a painting derived from lithographs, not one made to be turned into them.

No one has analysed the pigments. A list drawn from period practice would only be a guess, so this guide does not give one.

You die on 9 September 1901. In 1902 Maurice Joyant, your friend, dealer and executor, marks the works in your estate with a small red stamp, your monogram in a circle; on this canvas it sits at lower left.

In April 1902 Le Figaro illustré devotes an issue to you, and prints a photograph of the painting as Une Table au Moulin Rouge. By then it has been cut. Only a rectangle of about 124 by 94 centimetres remains, with the table group, restretched with its edges folded round the stretcher. The face at the right and the strip along the bottom have been cut off in one L-shaped piece, folded and presumably stored; a paint loss still shows where it was folded. Her sleeve, left in the rectangle's corner, was evidently painted over with the ochre of the floor.

Heller's case: the estate stamp is on the cut-off piece, so the canvas was still whole when it was stamped in 1902, and was cut afterwards, “under Joyant's immediate direction”. In 1899 you had been confined in an asylum to dry out, and you were widely called insane and degenerate. The 1902 issue was, in Heller's words, “a carefully orchestrated denial” of that, and a garishly green face made a poor argument for your sanity.

The museum is more cautious: it says “the artist or his dealer” cut the canvas, perhaps because her face made the picture hard to sell.

In 1909 the writer Hermann Esswein described the cut-down picture without illustrating it; Heller wondered whether the rejoining was already under way. By June 1914, when the Manzi-Joyant gallery held a retrospective, the painting was whole again. Two months later the Gazette des Beaux-Arts printed the first photograph of it rejoined.

The restorer laid both pieces on a new lining canvas, filled the tack holes with plaster and painted over the seams. One tacking margin had been cut off, leaving a gap, so the rectangle was shifted down about an inch to close it. That is why the edge between the ochre panelling and the green doors jumps upward behind the green-faced woman's head. Her hair and collar were altered, the two “antennae” on her hat, clear in your 1895 images of her, were restored wrongly, and flower-like shapes were added to hide the join.

The painting came to the Art Institute in 1928. For decades the museum read the story backwards: Rich, its director, thought the 1902 photograph showed your first version, enlarged by you a year later. Then, in the fall of 1985, the conservator David Kolch examined it and showed the canvas had been one piece:

• The paint and handling match on both pieces, and there is no overpainting where an enlargement would have needed it.
• Your thinned paint soaked into the ground; a later addition could not have matched that surface without traces.
• X-rays show brushstrokes, for example on the bentwood chair, running from one piece into the other.
• Heavy threads in the canvas run straight across the seam.