I've spent a whole week removing many years of wall paper...in a victorian house. You can see the wall prior to plastering and the plaster once dry....its obvious looking that there seems to be a reaction with the original wall covering. The plaster where it is light is powdery and you get residue on your hand if you rub the wall, the darker areas are sound. My question relates to how best to manage this? Does it need covering with something to stabilise it and re-skimming or what would you suggest, special paint? Lining paper? Any advice greatly accepted.