NewsProject delivery The restoration of the Statue of Liberty, seen on this 1984 cover, presented numerous challenges. Liquid nitrogen at -320°F was used to remove seven layers of interior paint, followed by blasting with sodium bicarbonate to remove a layer of coal-tar paint. The most ponderous part of the job was replacing the iron armature, a network of 1,350 iron bars ending in 1,500 U-shaped copper saddles flush-riveted to the 80-ton copper envelope.