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Appears in playback after a new recording has been made over an old one. This color noise band, called the moiré or rainbow disturbance, occurs because some of the old recording is being played along with the new one. It disappears going down from the top until the fully erased portion of the tape enters the video drum. The full erase head is unable to remove all of the old recording because it is located ahead of the drum and before the spinning video heads. Because video scans are slanted some of the signal stays behind after a recording is terminated. This usually isn't an issue during normal recording, but when performing an edit it is desirable to clear this old signal away and eliminate the rainbow. Flying-erase heads are used in high-end Betas to do just this. The rainbow effect does not appear in recordings made using a totally blank cassette.
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