Home Repair and Paint Guide

... Any defects on the walls will be magnified by the wallpaper, so take your time and make sure all problems have been corrected. You can hang new wallpaper over old, but it’s usually best to remove old wallpaper and start with a clean surface. Moisture from the pasting process can loosen the old paper, and ink can bleed through new paper unless you seal it with a special primer/sealer. Old vinyl paper could prevent adhesion of the paste. Only consider applying new wallpaper over old if the old paper is in good condition, smooth, only one layer thick, and will accept the paste. Make sure the old paper is tightly bound to the wall and has no loose areas. To prepare a papered surface, re-paste and roll any loose seams, repair nicks and rough spots, and flatten overlapping seams by removing the excess with a razor knife. Starting at the bottom, wash the wall with a solution designed for this task, or use ammonia and water, and let everything dry completely. To check if ink will bleed from the old paper, moisten a small piece of the old paper with a clean sponge. If ink comes off on the sponge, apply a primer/sealer designed for the purpose. If the existing paper is nonporous, use vinyl-to-vinyl primer to ensure adhesion and prevent mildew. For walls that are not papered, or where paper has been removed, first clean the surface to remove debris. Fix any imperfections such as nicks and high/low spots. Then apply a special primer designed for use under wallpaper. This prevents the paste from penetrating too deeply and also keeps the adhesive liquid a little longer, allowing time to slide the paper around for proper alignment. Wallpaper must be hung plumb for a professional job ...