How to Reattach Loose Wallpaper Seams and Edges
Roll the seam or edge with the roller.
Don’t press down too hard, because you’ll take out too much of the glue and the edge will lift again. Also, if you have embossed or textured wallcovering, pressing down too hard will flatten the design.
Wipe off excess adhesive with a damp sponge. If allowed to dry, the excess adhesive will dry with a noticeably shiny finish.