When tape is scratched or worn from use, the magnetic material containing recorded information is easily affected, resulting in partial or complete information loss perceptible on playback. “Single, well-defined scratches should be distinguished from general mechanical wear and tear, which takes the form of many tiny scratches. Tape wear is the result of frequent playback, and is characteristic of exhibition and viewing copies”1 in the case of video, and well-used listening copies of audio. When tape is damaged by mishandling, scratches may be introduced in any direction or location on the media. “In this case, the resulting noise bands will drift down the screen from top to bottom, or vice versa…. Only if the scratches actually damage the control track or the areas at the start of each helical track where the vertical sync pulse is recorded will a vertically rolling picture occur.”2
“If the audio on the longitudinal track [of video] is affected, the volume with fluctuate, but it will be more stable than FM or PCM audio recorded on the helical tracks. The latter will react to even a mild scratch with snapping or crackling noises, or by dropping out completely.”3
Scratching may also occur during playback on a poorly maintained device. “Single [horizontal] scratches … nearly always occur while the tape is being drawn through the player or cassette… [in the presence of] dirt, dust or debris along the tape path, or by the tape guides that are worn, maladjusted, or damaged in some other way. Because scratches running lengthwise along the tape always cross the helical video tracks at the same height, the stripes or bands of noise remain stationary on the screen.”4
Iraci cautions that “playing a scratched tape can generate debris from the scratched areas that will contaminate the playback equipment and could lead to more scratching.”5
Can it be fixed?
Loss of magnetic material cannot be physically repaired. The most efficient solution is to replace a scratched or worn tape with a new copy produced from an undamaged, unworn master tape. If a master is not available, the tape may be digitized, and then digital restoration techniques may be employed to alleviate the artifacts.
Example of Moderate Tape Damage. This portion of the tape is crinkled, and the folds of the tape can hold dirt that contaminate the head. This mix of the dirt contamination and tape deformation can cause severe video signal errors
Example of Tape Wear
1. Johannes Gfeller, Agathe Jarczyk, and Joanna Phillips, “Scratches and Tape Wear” in Compendium of Image Errors in Analogue Video (edited by Swiss Institute for Art Research, Zürich: Scheidegger & Spiess, 2012), p.94, videos 46 & 47. ↩
2. Gfeller et al., “Scratches and Tape Wear”, p.94. ↩
3. Gfeller et al., “Scratches and Tape Wear”, p.94. ↩
4. Gfeller et al., “Scratches and Tape Wear”, p.94. ↩
5. Joe Iraci, Remedies for Deteriorated or Damaged Modern Information Carriers, Canadian Conservation Institute Technical Bulletin 27 (Ottawa: Canadian Conservation Institute, 2005), 14. ↩