In Free Radicals he used black film stock and scratched designs into the emulsion. The result was a dancing pattern of flashing lines and marks, as dramatic as lightning in the night sky. In 2008, this film was added to the United States National Film Registry.
Lye continued to experiment with the possibilities of direct film-making to the end of his life. In various films he used a range of dyes, stencils, air-brushes, felt tip pens, stamps, combs and surgical instruments, to create images and textures on celluloid. In Color Cry, he employed the “photogram” method combined with various stencils and fabrics to create abstract patterns. It is a 16mm direct film featuring a searing soundtrack by the blues singer Sonny Terry.