Pablo Picasso, famous for pushing the boundaries of art with cubism, also broke with convention when it came to paint, new research shows. X-ray analysis of some of the painter's masterworks solves a long-standing mystery about the type of paint the artist used on his canvases, revealing it to be basic house paint.

Art scholars had long suspected Picasso was one of the first master artists to employ house paint, rather than traditional artists' paint, to achieve a glossy style that hid brush marks. There was no absolute confirmation of this, however, until now.

Physicists at Argonne National Laboratory in Lemont, Ill., trained their hard X-ray nanoprobe at Picasso's painting "The Red Armchair," completed in 1931, which they borrowed from the Art Institute of Chicago. The nanoprobe instrument can "see" details down to the level of individual pigment particles, revealing the arrangement of particular chemical elements in the paint....