If this fails, re-wet the backing and allow to soak longer. If the above stripping solution is not working well enough, you may also try a solution of 2 parts water to 1 part white vinegar and use the same technique. If you have really stubborn wallpaper , obtain some Safe and Simple online, or Dif from your local home improvement store, and follow the bottle's directions to remove the remaining backing material. If you plan on painting the area you just stripped , you must ensure that all the glue behind the backing is removed. To tell if there is still glue remaining, wet the wall and feel it.
Any slimy areas mean there is glue left over.
To remove any remaining glue, mix 2 tablespoons of liquid fabric softener into a gallon of water and scrub. You must also carefully rinse the entire wall surface so there are no traces of paste or wallpaper stripper remaining behind, before you paint. You can also obtain a paper scoring tool such as the Paper Tiger to score the paper and perform the above steps for removal. Use of paper scoring tools usually will damage the drywall underneath the wallpaper, but are gentler on plaster walls.