Im living in a 90-year-old home and want to really fix it up, starting with my kitchen. Last night i noticed the old wallpaper was bubbling and pulled it off to reveal this gritty, cement-looking stuff. What is it and how can i fix it? If i can, is there a good how-to video on it? Thanks!
Hard to tell exactly but it looks like the finish coat of plaster has separated from the base coat.
You can peel the loose areas and patch using drywall compound.
I would use the dry compound and mix to a pudding like consistency. Take great care removing loose areas. A small area could turn into a huge area real quick.
Another solution is to remove all plaster down to studs and finish with drywall.
Good luck and thanks
Plaster Walls http://www.bobvila.com/articles/1037-how-to-patch-plaster-walls/