I'm taking down wall paper in my 1920s house. The walls are plaster/lath. At some point, the room seems to have been skim coated, primed, and then wallpapered. The wall paper has come down fairly easily: pulled down a thin layer, wetted the paper layer underneath, and then pulled down that paper layer easily. Around the radiator, however, an under-layer pulled up as well. It seems to be made out of a sturdy paper like material, with perhaps fiber-glass embedded in it? There seems to have been a skim coat put over some parts of this layer. Any ideas on what I'm looking at and how to proceed? (The vertical line in the picture is a pencil line, not a seam)
It is likely wall liner. It is a heavy plain paper that is applied prior to the outer wall paper. You could think of it as a thick coat of primer that will hide a multitude of problems. I have seen it applied over dark patterned paper so a lighter pattern can be applied with stripping the walls. I have also seen it used over the scratch coat or when the wall has a lot of repairs to give the wall a smoother appearance.