Yes from what I understand you can't degauss 3590 tapes.  This is because
they have factory written servo tracks that would be destroyed in the
process, and make the tapes useless.

Apart from writing some junk data all over the tapes, there is an erase
command I believe.  In Aix its something like "tctl -f /dev/rmtxx erase"

But again this writes along the whole tape, and with 3200 carts will take a
long time.

My advice would be.  If you are paranoiac, or you do not know where the
carts will end up or do not trust the new owners to act in good faith then
you should destroy them.

What value does your organisation place on its data privacy V the secondhand
value of the cartridges ?

Jason Bamford
Tivoli EMEA