Question: My more than 60-year-old house has lath and plaster walls and ceilings. For some reason (perhaps dampness) we have found a paper-like covering peeling off the plaster in the bedroom. Was it customary to put such a cover over the raw plaster in those days? When we peel off this layer and get down to the raw plaster, should we apply a sealer coat before painting?
Answer: The paper could be old wallpaper. Make sure that the dampness problem, if indeed there is one, is solved before you do anything. It could be caused by a leaky pipe in the wall or a leaky roof. Before latex paint came along, you had to seal a plaster wall with shellac before applying the oil-based paints that were the norm in those days. If the plaster is in good condition and, like virtually everyone these days, you use a water-thinned paint, this shouldn't be necessary. Be sure to apply at least two coats of paint (three for a better job), after filling all the cracks and giving the walls a light sanding. It wouldn't be a bad idea to sand after the first coat of paint, for a really first-class job.