What compound is best to use when skim coating a plaster wall that had wallpaper removed?
I've used regular joint compound, thinned with water quite a bit. Be careful with any areas where the wallpaper pulled up the outer layer of drywall and exposed the brown paper - those will tend to bubble up when you skim over them. You might have some success with painting over those areas with something like Kilz, but even then, you might get bubbling. In that case, I use a utility knife to cut out the offending bubbles, and skim again. Thin coats should help reduce instances of bubbling.