We hang prepasted wallpaper (let it in water for 15 sec and booked it for 3 min as the instructions say) and wanted to smooth it with a brush. So much adhesive came out everywhere, we could not believe it and thought there is nothing left for the adhesion. So we just applied very light pressure, but then the wallpaper seems to have wrinkles and small bubles. We hang just two strips - let it on the wall over night and discovered that the adhesive is still wet. We had already wallpapered few rooms with prepasted wallpaper, but never had such a problem. Do you think smoothing with the brush is fine, eventhough so much adhesive comes out? Any other suggestions?

I have a large bedroom in which the walls and the ceiling have been covered with soundproofing. The soundproof material is rough and very porous (pieces of the surface material can be scratched off easily). Lots of nails to cover as well. How can I cover the ceiling part without adding more weight? Or...can I add another layer such as tiles or paneling or thin planks without fear of being too heavy on the ceiling. I would prefer to seal and paint the surface, what to use?