Water leaks from the roof or the floor above can leave an ugly stain on the ceiling that a fresh coat of paint alone won’t hide for long.
The first step in fixing the problem should be ensuring that the water leak has been resolved. As for the ceiling stain itself, Donovan says the trick is to cover the stained area with B-I-N shellac sealer primer; wear eye protection when applying. Once it dries, paint the ceiling with confidence that the stain won’t reappear.
The one-two punch of sealer and paint also works on ceiling stains caused by cigarette smoke or mildew.