This artist duo has pursued a unique long-term project since 1998, putting together a vast collection of unfixed light sensitive papers, glass negatives, and films, mostly dating from 1880 to 1990. Samples are mounted and displayed and, over the course of several exhibitions, exposed to light, causing them to evolve toward color saturation. Instead of looking at still pictures, viewers perceive a kind of reality for themselves. This book features the entire test catalog put together to date, showing some 900 different papers and light-sensitive supports.