Do you know why there are seams when install the plain wallpaper ?
(1) During install, you must check whether there is a "up and down label(↓↑)" on the wallpaper. If have this logo, the wallpaper should be pasted on the front and back. If there is still color different after the front and back pasting, you can try to paste it again like normal.
(2) When install plain non-woven wallpaper, try to avoid overflowing glue and avoid wiping. Once the wiping is strong, it will leave marks. If the glue overflows, wipe the overflowing glue within the smallest range, and act gently on the darker color plain wallpaper.
For more details, pls contact Shunmei Wallpaper Factory.