Some critics regard this as Lye’s greatest film. He reduced the film medium to its most basic elements – light in darkness – by scratching designs on black film. On screen his scratches were as dramatic as lightning in the night sky. He used a variety of tools ranging from dental tools to an ancient Native American arrow-head, and synchronized the images to traditional African music (“a field tape of the Bagirmi tribe”). The film won second prize out of 400 entries in an International Experimental Film Competition judged by Man Ray, Norman McLaren, Alexander Alexeiff and others, at the 1958 World’s Fair in Brussels. In 1979 Lye decided to shorten this already very concentrated film from 5 to 4 minutes. Stan Brakhage described the final version as “an almost unbelievably immense masterpiece (a brief epic).” In 2008 Free Radicals was selected by the U.S. Library of Congress as a “classic film” that it would “preserve for all time.”