The key to successfully stripping wallpaper is to take your time, prepare the wallpaper properly and work methodically. Make sure you have everything you need for the job, including any specific wallpaper removing tools such as an orbital paper scorer and a clean paper knife.
As you will be applying water to the wall, and there are probably going to be light switches and sockets on the wall, you need to think about safety. Consider cutting a square of plastic from a carrier back and taping it over sockets and switches before you start. Make sure you switch off the power at the consumer unit if working anywhere near electrical fixtures with steam or water.
Cover the floor with dust sheets and move any furniture away from the walls. If you have one, run the orbital paper scorer over one whole wall. This tool is not essential to stripping wallpaper, but it can make this labourious task a lot easier and they do not cost very much to buy. Fill a bucket with warm water and add a little wallpaper paste and a tiny amount of washing up liquid. The paste will help the water stick to the paper and the washing up liquid will help the water penetrate the paper.
Using a large sponge or pasting brush, wet the whole wall well (avoiding getting water on sockets or light switches) and leave the water to soak into the paper for 5-10 minutes. If you have not scored the paper, a second coat of water after 5 minutes can help with the soaking process.
After letting the water soak in. find a seam in the paper and try to slide your paper knife in at an angle. If the paper knife slides under the paper easily, the soaking has worked as it should and you can start to strip the paper in earnest. If the paper is still hard to lift, leave it to soak for a few more minutes.
As you strip the paper, make sure you keep the paper knife (which should be a wide bladed one if possible) flat against the wall and work in a diagonal scraping motion rather than up and down or left and right. This should help to reduce marks to the wall underneath. If the paper is taking a long time to strip away, don’t be afraid to add some more water to the rest of the wall that might have dried out as you have worked.
If the paper is proving particularly difficult to remove, and no amount of soaking seems to be doing the job, it might be a good idea to borrow or hire a steam stripper.
When stripping around light switches or sockets, check to see if the paper goes behind the fixture. If it does, turn off the power at the consumer unit, then loosen the faceplate and carefully strip the wallpaper away.
Washable or Heavy Wallpaper
When planning to strip heavier paper, washable paper or wallpaper which has been painted over, the use of a orbital scorer is a much more important part of the process. Without scoring these much tougher surfaces, you will have real trouble getting the water to penetrate enough to loosen the paste.
Score the paper and soak well with the water/paste/washing up liquid mix described above. With heavier paper, it can sometimes be better to use a clean hand-held garden spray gun to apply water to the wall. However, if you don’t have one of these, a sponge or pasting brush will do the job. You just might need to apply the water more than once. Allow the water to soak in for at least 10 minutes before testing an edge of a sheet with your paper knife. If the paper is still stuck fast, leave it so soak for a while longer and consider applying more water.
Vinyl or Easy-Peel Wallpaper
These materials are not as likely to tear as normal wallpaper so you can treat them differently when stripping them. Find a corner of a sheet and using a fingernail or knife blade, peel back a corner. Fold the corner back against the wall and start to pull it off the backing paper. Keep the hand holding the paper against the wall as you peel the paper/vinyl and peel upwards, as this will help to prevent the backing paper being pulled off at the same time.