We have recently decide to paint one of our bedrooms. When we went to pull off the old paint, it appears it may have been wall paper and it went all the way down to the brown part underneat the sheetrock layer. We have since put about 4-5 coats of plaster over the sheet rock to bring it back to paintable ready. The problem is some of the old paint stayed on in the joints to keep those together since it did not want to come off. The guys at home depot said to leave it so as not to have to seal it off again. Is there an easier way to add the plaster to the wall besides using the spatula and just applying it. It seems to be taking forever to get it at the same thickness as the old wallpaper that we left on to keep the joints sealed. Since this is going to be for a cat room, I told my wife we shoudl just leave as is and start to prime and paint since it does not need to be perfect.

Hopefully this made sense.

 

Since paint shouldn't pull off of an interior wall, I agree it must be wallpaper that's been painted over. Hopefully you have removed all the loose paper. I'd use a 10" or 12" drywall knife to apply the joint compound. If you thin the j/c a little with water and mix it well - it will spread easier. It may take several coats, sand and prime when dry.

If the drywall face paper is removed, the raw gypsum should be sealed with Zinnser's Gardz. That will prevent the moisture in the j/c or latex primer/paint from causing the paper around the edge of the repair from coming loose.

"The guys at home depot said to leave it so as not to have to seal it off again"
I don't understand that statement what would be sealed off?

 

One of the biggest mistakes any home owner can do is paint over wall paper. It will now be nearly impossible to get it off the wall in the future, now that there's two layers of paint it will be impossible.
If I was give this room to restore I would not even bother to try and get off the old paper, I'd strip the walls back down to bare studs and resheetrock. It would be faster and come out smoother.

 

One way to make it go a little easier for you is to thin your mud down to pancake batter consistancy. I know you said you used plaster but you should use lightweight joint compound. At home depot its called usg plus 3. It comes in a mostly blue bucket or box. Once you have it thinned down roll it on the wall with a paint roller. Then take a 12" drywall knife and pull it down the wall so it smooths out all of the roller nap marks.












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