actinism
/ˈæktɪnɪzəm/
noun
- The property of light or other radiation that causes chemical changes, such as in photography or the fading of colors.
- Early photographers relied on the actinism of certain chemicals to capture images.
- The actinism of sunlight can fade the colors of a painting over time.
- The fabric's dye was resistant to actinism, so it stayed bright even in direct sun.