As soon as an artwork is released into the world it faces numerous threats. Some, such as light, especially daylight, and the air itself—its oxygen and the water that it air holds—are basic elements of our environment. Other threats, such as pollutant gases, are largely man-made.
Given the inherent and external risks to works of art on paper, the frame must provide a protective envelope in order to, in effect, slow time. The framer must assess the hazards and choose the correct materials and procedures to minimize them. Art materials, the environment’s effect on them, and the preservation function of the frame for works of art on paper are the subjects of these notes.
– Margaret Holben Ellis, The Care of Prints and Drawings