Thought I knew my walls: plaster walls after removing paper
I've searched through pages and pages of questions on removing painted wall paper, and pages and pages about repairing plaster, but I need a little help with my walls underneath the paper.
The house is old (between 1910 and 1920), so I thought I had three layer plaster walls. I also happened to have decades old wall paper and coats and coats of paint on top. The walls were not pretty but structurally sound (keys attached to the lath and such). With the wall paper seams obvious from a mile away, and huge portions of the paper peeling off, I decided to rip the wall paper in one area.
I was hoping I'd get down to the white coat of the plaster, and be able to repair and paint on top of it. Well, I got all the paper off (it was easy...I'm not sure that wall paper glue had much adhesive left in it). Some of the largest cracks in the wall paper had been caused by the white coat cracking/chipping/bubbling off the base plaster. These holes I was expecting.
What I wasn't expecting was that once I got the wall paper off, it still looked like there was some sort of wall paper as the white coat. By this I mean there are distinct lines where the wall paper seams were on the plaster that look almost like where two pieces of drywall come together. These lines are where the wall paper seams were, and are bubbled up from the plaster underneath and are wavy.
Is this white layer really the white coat plaster? Do I have to remove ALL of it and start with a new finish layer? Could I just get rid of any of the white coat not attached to the base plaster, making a bunch of holes to patch?
Thanks for any help (or pointing me in the right direction)