In most cases of multiple wallpaper build up though the plaster will be a lost cause.
Hanging wallpaper on plaster walls.
If you encounter wallpaper that s been painted over first try the wallpaper stripping.
Sizing is a compound of chemicals that acts as a buffer between the wallpaper backing and the plaster surface.
Remove as much furniture as possible from the room.
Place any large pieces of furniture such as sofas in the center.
The best option mostly depends on the weight of the picture in question.
Take down pictures mirrors or anything that s leaning or hanging against your walls.
Adhesive picture hooks are the best way to prevent damage when hanging a picture but pre drilling the hole will usually prevent cracks and chips from forming as well.
Then size the walls by applying a some ready mixed paste diluted with water to stop the plaster absorbing all the moisture when you come to actually hang the paper.
How to wallpaper or paint directly on plaster 1.
For speed even application i use a roller.
Although this may sound like a measurement process it actually refers to treating plaster walls with a product that allows the paper to stick better but not so tightly that you can never remove it.
Best o luck paul.
Firstly make sure plaster is fully dry 7 10 days depending on drying conditions.
Place these in another room.
Prepping plaster walls for paint wallpaper painted over wallpaper.
Pull out all remaining plaster and lath and re build the walls with drywall or to be historically accurate plaster and lath.