Years ago I used to erase VGS and 3/4" video tape cassettes with a bulk tape eraser...basically a big electromagnet strong enough to rearrange magnetic particles on tape. It was quite a time saver and more thorough than recording black on a tape from beginning to end. As long as one didn't mind a few dropouts on the re used tape it was a lot cheaper than buying new tape.
I've always used new tape, but I've got quite a stack of tape that has footage that will never again be used. I thought I should get some more mileage out of those tapes before they get trashed.

Any opinions.

I have heard from guys that know more than me that in doing that you stand more of a chance of wrecking the tape than any good it would do.

mike

Why bother erasing them? Just tape over them with the next job. You can make sure to tape 30 secs of black at the end to separate the new from any old footage...

1- miniDV tape is difficult to erase, you need a very powerful tape eraser. Normal ones won't cut it.

2- MiniDV itself has error correction (and sometimes dropout concealment), so that should reduce your chances of dropouts. So it shouldn't be as bad as with 3/4".