A double-cut is a paperhanger’s term for splicing two strips of wallpaper together. The edges of the strips are overlapped about 1″ on the wall, and then, bracing against a straightedge, a sharp razor blade and plenty of pressure are used to cut through both layers of wallpaper. Remove excess paper from both layers, and you have a perfectly butted seam.
The only problem is that it’s virtually impossible to do this without scoring into the wall, slicing through the top layer (or more). This cut makes the surface unstable, and when the new wallpaper dries, it shrinks and puts tension (torque) on the wall’s surface. This shrinking and tension can cause the wall to split and curl back, leaving a gap or a gaping wallpaper seam.
This is what you see in the photo.
To remedy this, I wanted to bridge the gap with something that would move with any shifting in the drywall, and that would not cause ridges under the new paper.
The new wallpaper was a thick, textured material, so I was not overly worried about ridges from the patch telegraphing through it.
I used strips from the paper backing of the old wallpaper / grasscloth I had just stripped off the wall to cover the cut wall areas. I tore the patches, rather than cutting, because the “feathered” edges of the torn paper would be less noticeable under the new paper than a sharp, straight edge would be.
The strips were wet from having been stripped off the wall with water, and the wall’s surface had damp paste residue remaining on it, so the patching strips adhered nicely to the wall surface.
But, to be sure, I brushed on Gardz, a penetrating sealer and “problem wall solver.” It soaked in, bound the surfaces together, dried, and made a taught, strong surface for the new wallpaper to go over.
Still, I made sure that my seams did not fall in the same exact spots as these compromised areas of wall. That greatly reduces the possibility of seams in the new wallpaper from curling back or pulling away from the wall.
As it turns out, because of the way I engineered the wall and various other factors, I did end up doing a double cut splice over this door. But I made sure it was not in the same place as the compromised wall surface. In addition, I protected the wall by putting a thin polystyrene (plastic) strip under the wallpaper before I cut, so that when I pressed my razor blade hard to cut through the two layers of cork, it did not damage the wall. Sorry, no pics, but there are other photos of that process on my blog, if you want to do a Search.