This dark plum-colored wallpaper is printed on a thick and spongy, white non-woven material substrate. It’s quite likely that a white line will manifest at the seams, because that white backing just wants to peep out. Some manufacturers prevent this by printing their dark colorways on a black substrate – but I was not so lucky today.
If the white edges of the paper can be colored to match the surface, it greatly reduces the chance of the seams showing. So I made a quick run to Texas Art Supply, and picked up three different “cures” for this problem: a permanent marker, a colored pencil, and a pastel (chalk) crayon.
It’s important that these coloring devices be applied from the back of the wallpaper strip, to prevent color from seeping onto the surface of the paper, which would result in a dark line along the edge of each seam, which can be as bad as seeing a white line.
The permanent marker, which usually works nicely on paper-backed vinyl papers, did not work on the non-woven material, because it bled a little onto the surface. I thought the seam looked bad, and tore the strip off the wall. Now the stress is on, because you only have so many strips that can be wasted, until you run short of paper to finish the room.
I continued to experiment. The colored pencil, which adequately colored the edges of my test sample while I was at the art supply store, once I got back to the job site, failed to add enough color to the edges of my full-length strips of wallpaper. But the pastel did a nice job of covering up the white line, while not getting color onto the surface of the wallpaper. To make sure, I wiped the surface with my dry hand, to remove any residual pastel dust.
Success!
Of course, all this would have been unnecessary, if the company had only printed their dark pattern on a dark backing!