Why does wallpaper deteriorate?

Wallpaper deteriorates for many different reasons. These can include the type and quality of the original materials, how the wallpaper was hung, problems with the building itself or through physical damage by people and poor methods of repair. Most wallpapers produced after around 1840, and particularly cheaper papers, are likely to have been made from poor quality, unpurified wood pulp, and may discolour and become brittle after just a few years. Dampness in walls and the environment of a building often causes staining, and can also lead to the failure of adhesives and weakening of the paper through mould growth. Damage can also be caused by over-exposure to light, which results in the fading of colours. The use of inappropriate adhesives for repair can cause irreversible discolouration and staining, and they will often fail after only a short period of time.