I bought a 30m roll of Delta 100 this week. When I opened the box there was a black light-proof bag inside which wasn't sealed shut (the outer packaging/box was sealed). Inside this I was expecting a tin - no, it was just the film! Will just the top couple of layers have been exposed or shall I bin it ?
Now you know, I'm sure you won't do the same mistake again.
It seems it is the first time you buy a bulk roll made by Harman.
They are all the same.
For your reference, if the box has a seal of any kind, only open it in the dark.
In your defence, on my Kentmere 400 boxes, it doesn't say to open only in a darkroom.
Foma rolls come in a sealed can clearly labelled to "open in the dark" only.
Inside they are the same as Harman, dark bag just wrapped around the film.
BTW, the film core for Harman bulk films is 1", while Foma uses 2" cine cores.
You should keep that core if you want later to use Foma films.
Most bulk loaders like the Watson 100 or the Computrol are made for 1" core.