A-D Strips provide a simple and safe method for detecting, measuring, and recording the severity of "vinegar syndrome" in your acetate photographic film collections. A-D Strips are dye-coated paper strips designed to detect and measure the severity of acetate photographic film deterioration ("vinegar syndrome") in film collections. These acid-base indicator papers change color in the presence of acidic vapor given off by degrading film, providing an objective method to document the extent of vinegar syndrome and to determine when microfilm should be duplicated.