Hidden meaning? X-rays reveal Joan Miró painted over portrait of his mother

Three clumps of raised paint, an old X-ray and months of scientific analysis and dogged detective work have revealed that a portrait of Joan Miró's mother has lurked, undetected, beneath the cobalt-blue surface of one of the Spanish artist's inimitable works for the best part of a century.

- Sam Jones

Between 1925 and 1927, Miró created a small, oil-on-canvas picture, titled Pintura (Painting), which he gave to his great friend the art promoter Joan Prats.

By that time, having made the inevitable artistic pilgrimage to Paris, experimented with fauvism, post-expressionism and cubism—in the process comprehensively dashing his parents' hopes that he might one day find stable employment as an accounts clerk—Miró had alighted on a freer, more individual style.

Pintura underlines what Marko Daniel, the director of the Fundació Joan Miró, describes as the artist's commitment to "exploding the conventions of painting, of pictorial space, of the way in which painting works". But it may also hold a deeper, hidden meaning that reflects the artist's attempt to break away from the bourgeois constraints of his family as he set out on his famous quest to "assassinate painting".

Five years after Prats' death in 1970, the painting became part of the collection of the foundation, which is based in Barcelona. Time, and humidity, had not been kind to the canvas, which had suffered micro-fissures and other damage.