This startling mechanism for promoting depolymerization relies on an additive that many plastics already contain: a pigment called carbon black that gives plastic its black color. Through a process called photothermal conversion, intense light is focused on plastic containing the pigment to jumpstart the degradation. The lab’s method has since been tried out on such post-consumer waste as PVC pipes, black construction pipes, trash bags, credit cards, even those ubiquitous yellow rubber duckies. It works on all of them.