A-D Strips are dye-coated paper strips that detect and measure the severity of acetate film deterioration, a.k.a. vinegar syndrome, in film collections. When placed inside a closed can, bag, box or cabinet in the presence of acidic vapour given off by degrading film A-D Strips change colour to indicate the severity of the level of acidity.  Each kit contains complete instructions, a reference pencil printed with four bands of colour that correspond to the level of acidity, as well as 250 detector strips (measuring 38 x 10mm)

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.

A-D Strip is a very sensitive indicator and senses the “Vinegar Syndrome” just by touching the film.

The color is blue when in the pouch. After taking the wanted number of testers out of the pouch, squeeze the air out and close the pouch carefully.

Take the lid off your film can, place the indicator on the film and make a note of the time. The reading can be done after 24 hours depending on the temperature.

For cold conditions expect 2-3 days for an accurate reading. 24 hours is based on 20 degree C.

Compare the reading with the color chart and make a note of the level of acidity. If the color changes to olive green (pH 4,6) you have reached the critical autocatalytic point, which is the point where you should consider separating it from the rest of the collection and begin to duplicate. If the indicator has not reacted within 24 hours nothing is critical.