Some time ago, someone on this list wrote inquiring about the use of
external labels on LTO1 cartridges.
Many other types of cartridges have a recessed area for applying an external
identifying label other than the bar code, but the LTO cartridges do not.

We also have a requirement for external ownership labels, and here is our
experience:

We bought some Avery non-removable printer labels, 3.5 x 3/4 inch.
We put one on the top rear of the cartridge (over the recessed arrow).
We put another on the back face of the cartridge (the surface opposite the
bar code - that one required trimming down a bit shorter.)

I did 200 forced mounts/dismounts of the cartridge.
Now this TSM server isn't terribly busy; 200 mounts should correspond to
something like 3 months normal use for our busiest tapes.

I had no peeling, curled edges, mount failures, or jams.
There are no scuffs or any indications of wear on the labels.

So we consider this an acceptable risk.
Granted the print is tiny, but it will suffice.

IBM LTO1 drives, IBM LTO1 cartridges.
YMMV.