Brownish discoloration in paper caused by the deterioration effects of acid and ultraviolet light.
Acid burn refers to the brownish discoloration and staining that appears in paper and artwork as a result of acidic deterioration. Over time, acids from mats, backing boards, or environmental pollutants migrate into the paper, causing visible staining. This process can be accelerated by exposure to ultraviolet light, which weakens fibers and intensifies discoloration.
Acid burn usually appears as:
Awareness of acid burn has shaped the framing industry's shift toward acid-free and conservation-grade materials. Many framers now educate clients on the risks of acidic mats and backing, emphasizing the long-term importance of archival framing for preserving valuable or sentimental works.
