Saving your roll ends is wise and highly recommended.
Think of it as cheap insurance. Here's a perfect example.
This wallpaper is no longer available, but the homeowner
had the foresight to store her roll ends away in a safe place. A towel
bar was ripped out of the wall leaving four small holes and torn wallpaper.
The bottom right section of this sheet was torn and missing.
The holes were patched, sanded and primed.
There wasn't enough material to replace the entire
sheet. But the repairs turned out beautiful.
This bathroom also suffered from loose and curling
wallpaper. Never use Seam, "VOV", or Border adhesive for
repairs or glue downs. You'll just be creating a future problem for
the person who eventually removes the wallpaper.
Roman 880, a pre-mixed/strippable adhesive, did
the trick as you can see.
