When working with Sheetrock after wallpaper removal, oil-based primer creates a smooth, paintable surface. Oil-based primers, which are heavier and more noxious than water-based primers, hide imperfections and repairs made after wallpaper removal.
Before adding any primer to the Sheetrock, the walls should be free of adhesive or debris. Use warm water and wallpaper removal solvent, working in small sections to avoid damaging the Sheetrock. Make repairs using spackling or joint compound, sand them smooth, and wipe the walls down again before applying the oil-based primer. When working with oil-based primers, make sure there is adequate ventilation in the room, and wear a mask for fume protection.