HELP!! I'm removing 96 yrs worth of painted wallpaper and I have found under the around the window (frame) where wall meets woodwork the plaster has gaps all around it. Some of it is very dark or black and around the bottom of this area black dust fell down. Is this something serious or just 96 yrs worth of dust that has accumulated. Do I repair this the same way I would do all other wall imperfections with mud and sanding?? If some of this wallpaper was in better shape I'd just leave it, but large cracks have appeared from being so brittle with all the paint on it. What a mess! What a shame people covered such beautiful smooth plaster walls. Guess I'm just one of these people that love to see the beauty of a real craftsman from yesteryear. Drywall just doesn't compare to a beautiful plaster wall one the paint goes up.