This might be because there are already too many layers on the wall (3 is the maximum suggested by most experts), or it may be because the old wallpaper has began to crack or peel and is no longer sticking tightly.
When confronted with this problem, you can tackle it in one of two ways: you can rent a wallpaper-removing machine which virtually “steams” the old paper off the wall or you can scrape it off by hand. A steaming machine would make the job a great deal easier and it will enable you to finish in a fraction of the time needed for scraping by hand.
These machines can be rented for from $20 to $30 per day from most paint and wallpaper stores and from practically all tool rental agencies. The smaller units are all-electric and need only be connected into an ordinary outlet to operate. Heavier capacity units are also available. These put out substantially more steam, hence they make any job go faster.
All wallpaper-removing machines work on the same fundamental principle. Water in a tank is heated up to the boiling point so that steam is produced. This steam flows through a hose into a hollow applicator pan or plate which is attached to the other end. This pan has a series of small holes on the working face wherein the steam escapes. When this face is held against the wall, the steam soaks into and dampens the paper so that it can readily be stripped off by scraping with a wide putty knife.
When utilizing one of these machines, hold the pan flat against the wallpaper and keep it in one spot for about 30 seconds. Then begin moving it along gradually, holding the pan in one hand while scraping the softened paper off with the other hand. Normally, it is better to work from the bottom up, because the rising steam will tend to soften the paper immediately above it. For the same reason it is best to do walls first and ceilings last if both areas have wallpaper to be removed.
Since the room in which the machine is being used will quickly fill up with steam, it’s important that doors leading to other areas of the house are closed and that windows in the room are opened at the top to insure decent ventilation and to permit extra moisture to escape freely to the outside.
Though they speed the job up substantially, steamers can’t be used satisfactorily in rooms which have wallpapered ceilings, when the paper on the ceiling is not to be removed. They may also cause water-spotting of painted ceilings which will not be recoated, and can really remove part of the paint on ceilings that have been coated with water-soluble paints. In these cases—or in the event that a wallpaper steamer isn’t available —hand soaking and scraping will be required. Plain hot water can be used, but the job will go faster if a liquid wallpaper remover (available at paint stores) is added to the water. These liquids help the water soak through and soften up the paste underneath.
To utilize the water to the wall, a large paintbrush can be used. A more effective method is to use a pump-type garden sprayer or a regular paint sprayer. A wool-type paint roller can also be used. No matter the method of application used, soak the paper exhaustively, a section at a time. If there are several layers of paper on the wall, two or three repeat applications may be needed. Scrape off with a wide putty knife, re-wetting areas as necessary when they begin to dry out.
A lot of wallpapers have plastic coatings to make them more washable. This will avoid penetration of either water or steam. To soften these papers, it may be necessary to cut through the plastic coating so that the water or steam can permeate to the back to soften them up. This is best done by rubbing vigorously with very coarse sandpaper till the surface is thoroughly scratched. Then steam or soak off as just described.