Visible color stains on film stock from dye transfer — result of wear or poor storage. Signal that source material is degraded and needs restoration.
When digitizing archival material or working with older film reels, you'll quickly notice them: fine, evenly running discolorations that appear like tracks across multiple frames. These are Dye Tracks — dye migration traces that occur when a film's emulsion is stored under pressure for too long or in humid, warm climates. The dye literally migrates from one layer to another, leaving behind lines and streaks that usually run parallel to the film edge. In editing, they are a warning sign: the material is degenerating.
In practice, the problem often only becomes apparent during digital transfer. You digitize a 16mm reel from the 1970s, and suddenly you see vertical color gradients that never came from the camera. This happens because old color films — especially Kodachrome and early Eastmancolor — are susceptible to this chemical migration. Improper storage conditions (too warm, too humid, poor ventilation) accelerate the process dramatically. Incorrect spooling under tension can also cause it. The tracks are irreversible — you can't simply remove them with denoising filters because they run consistently across multiple frames.
In the editing workflow, this means: recognize Dye Tracks early. Inspect your source material carefully — not just for scratches and dust. If the discoloration tracks are severe, you'll likely need a color grading strategy to mask or compensate for them. With multi-colored tracks (red, green, blue components migrating differently), often only digital repair is possible — selective channel adjustment or simply accepting that this material bears aesthetic scars. Some editors even intentionally incorporate them into the look if it fits the visual narrative. For archives, dye tracking is a sign of necessity: restorations must be carried out early and correctly before the material completely deteriorates. The message is clear — old films need care.