— The wallpaper strip is crookedly glued. The reason for the curvature lies that the vertical line was not originally marked on the wall. This is done with the help of a water level or if there is no one, then you can use the usual plumb. Thus, ensuring the evenness of the wallpaper. To eliminate this type of marriage to great regret, there is no way. If the skew is not too noticeable, then it is better to leave everything as it is, if the skew is very striking, then you have only one thing left — this is re -pacing the wallpaper.