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. The adhesive is usually sold in pouches or boxes as flakes that are mixed with water to produce the paste, it is also available ready mixed in tubs.
Wallpaper bubbles are bumps in the surface of your wallpaper caused by air pockets trapped between the paper and the wall. Almost every wallpapered room, even those with the wallpaper hung by top-tier professionals, develops a few wallpaper bubbles as the paper or the wall warps slightly over time. Luckily, there are some easy DIY fixes that will leave your wallpaper looking smooth and completely free of wallpaper bubbles.