Size a plaster wall to prevent loss of adhesion by absorbing of water from the paste.
It also makes the wall slippery, which helps when positioning each length.
It is important to follow the manufacturer's instruction when mixing the proportions
together prior to sizing. Size is an adhesive (see Choosing the wallpaper adhesive) similar to glue and is much easier to remove when
still wet.
Have a damp cloth ready to remove any surplus size from woodwork or plastic switch/plug coverings.
