Apply wallpaper paste.
For un-pasted wallpaper, apply pre-mixed paste using a large pasting brush or paint roller, working from the middle to the ends. Be sure that all areas are covered with paste with no un-pasted spots. Gently fold the top of the sheet down to the middle so that the pasted sides touch. Next, fold the bottom edge up to the middle. This allows the paste to cure and keep it from drying out. Do not crease the wallpaper.

Wallpaper adhesive or wallpaper paste is a specific adhesive, based on modified starch or methylcellulose, used to fix wallpaper to walls.

Wallpaper pastes have a typical shear thinning viscosity and a high wet adhesive tack. These properties are needed to slow down the penetration of the adhesive into the paper and wall, and give slow bonding speed which gives the wallpaper hanger time to line up the wallpaper correctly on the wall.