Big blue

Anyone who visits the Sistine Chapel in Rome cannot fail to be impressed by the results of a 20-year restoration project that has brought Michelangelo’s frescoes back to their original majesty. Most notable is the brilliance of the sky blue that almost illuminates the Last Judgment on the altar wall of the chapel. But, recent NMR analysis of the ultramarine pigment used to produce this stunning blue suggests its tendency to fade could see the Last Judgment and other works ultimately perish unless art conservationists act now. Alexej Jerschow of New York University, Eleonora Del Federico of the Pratt Institute, and their colleagues have used solid-state NMR to find out why this blue pigment fades. It appears that a break down of the pigments zeolite structure releases the sulfur-containing chromophores. Their findings could provide art conservationists with vital information how to protect works.