The erasure of a magnetic tape, or the degaussing of the tape recorder heads.
"I received my CD that I had made from a cassette by you. All I can say is "beautiful". I didn't have the best component set to make the cassette on, but the CD sounds fantastic! I have a lot of old cassettes of records that are hard to find for which I will be converting to CD, by your company! It will probably be a while because my component ..."