Using A-D Strips

What are A-D Strips?

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, developed and manufactured by IPI, are dye-coated paper strips designed to detect and measure the severity of acetate photographic film deterioration ("vinegar syndrome") in film collections. Vinegar syndrome is a slow form of chemical deterioration that causes film to shrink, buckle, and emit a strong vinegar odor. 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 acetate cinema film, microfilm, and pictorial film should be duplicated. IPI received a Technical Achievement Award from the Academy of Motion Picture Arts and Sciences in 1997 for developing A-D Strips. Each package contains 250 detector strips (1 1/2" x 3/8") and a color reference card. Detailed instructions for use: (download PDF). A-D Strips are available for purchase through the Image Permanence Institute.

Note: in 2022, the product packaging was updated to include a five-color reference card instead of a pencil, and PDF instructions instead of a printed booklet.

How do A-D Strips work?

When placed inside a closed can, bag, box, or cabinet, A-D Strips change color in the presence of the acidic vapor given off by degrading film. As the level of acidity increases, they change from their original blue color through blue-green, green, and yellow-green, and finally to bright yellow. The reference card included in the kit is printed with five bands of color, numbered from 0 to 3; these correspond to strip colors at five levels of acidity. After exposure to film in a sealed enclosure for the required length of time, the strip color is compared to the color bands on the card. The number of the band most closely matching the color of the strip is recorded.

This shows collection managers how far deterioration has progressed and whether existing storage conditions are good enough to preserve their film. They can then set priorities for further actions, such as improving storage conditions or setting up a film duplication program.

Use A-D Strips to learn the approximate extent of acetate degradation in individual films, or use them as a survey tool for gaining an overview of film condition in an entire collection and to get a more accurate picture of storage and duplication needs.

What types of film can be tested?

Three types of plastic have been used in film manufacture: Nitrate was used from 1890 to 1950, acetate from 1925 to the present, and polyester from 1960 to the present. A-D Strips are recommended for use only with acetate film. The film may be in any format: sheet film, roll film, cinema film, or microfilm. For a full discussion of film history, identification, deterioration, and storage recommendations, see the IPI Storage Guide for Acetate Film.

Interpreting A-D Strip Results

A-D Strip Level	Film Condition	Recommended Actions
0	Good—no deterioration	Cool or cold storage
1	Fair to Good—deterioration starting	Cold storage Monitor closely
1.5	Rapid decay starting—point of autocatalytic decay	Cold or frozen storage
2	Poor—actively degrading	Freeze Copying advisable
3	Critical—shrinkage and warping imminent, possible handling hazard	Freeze immediately Copy

---