Walls and Ceilings - Lath/Plaster water damage

I've just peeled one layer of wallpaper off of my lath and plaster walls. What I've found is an area with water damage. In this area the wall bubbled out a bit which allowed me to scrape what i thought was plaster off of the wall. What I found underneath was another layer of even uglier wallpaper.

Question1: What is that ~1/16 inch layer that looked like plaster yet had wallpaper beneath it?

Question2 : Can I simply skim coat over the top of the old wallpaper again (assuming it is some sort of plaster like skim coat material)? The leak that caused the damage was fixed 6 months ago so everything seems to be dry. The area to be covered is about 7 square feet.

Thanks in advance for any help!

well they may have skim coated over the paper years back cause they couldn t get it off

but to paint it-is it sound ,adhering well?
if it is you can prime with OIL and then skim
you must use oil because the water in the repair compound may absorb into the wallpaper and create problems

if you dont like oil buy zinnser odourless, oil based but hardly smells and dries fast

good luck

What product do I skim coat it with? I've never worked on this stuff before. I have mudded drywall but I assume this will require some other product besides joint compound.

i use sheetrock 45
you only have about 25 min to use what you mix

u can also buy sheetrock 20 (about 15 min)

sheetrock 90(about 30 min)

regular mud will work, but sheetrock cures stronger

go buy a 14" knife

good luck