Inside a 1904 scrapbook related to the Girls Department at the Perkins Institution in South Boston the Archives staff was pleased to find that photographs pasted into the pages had duplicated themselves! A clear copy of the images transferred to the opposite page of the book through a damaging process called acid migration or acid transfer.
Over time as acidic lignin found in paper oxidizes, it creates yellow and embrittled pages. The transferred image is surprisingly detailed and accurate like a reflection on a still body of water.
“Acid-Transfer-Grams.” Perkins Archives Blog, Perkins School for the Blind, Watertown MA. April 17, 2015.