Slightly moisten the cleaning applicator and re-moisten it as needed. Do not saturate the applicator with alcohol. Too much alcohol can produce streaks and result in a longer drying time. Clean a small area at a time. Repeat the application if necessary to remove foreign matter such as china marker, crayon, or other wax-based markers.
Isopropyl alcohol is available through most chemical supply houses.
Purchase it in small containers. When you clean materials, pour out only enough for current use, and then discard any alcohol that remains after cleaning. Keep the original container sealed to prevent the alcohol from taking on water content from the air. Using isopropyl alcohol on these negatives may cause coloration of the cleaning swab or cloth. Caution Do not use isopropyl alcohol to clean nitrate-based film manufactured before 1950.