There are two reasons to prepare your walls before installing wallcovering. It ensures that your wallpaper will adhere correctly to the wall and it aide’s future removal. As wallpaper dries, normally over a 24 to 48 hour period, there is a significant amount of pull as the paper contracts. If the wallpaper has not formed a good bond, it will pull away from the wall. Additionally, when the paper is later removed, it may damage the covering of the underlying surface. Proper preparation will ensure the best results from your wallcovering.
The first step is to repair any defects in the wall surface. With drywall, any dents, nail holes, or surface imperfections should be filled with spackling or drywall patching compound. After the proper drying time for the particular compound you are using, the repaired areas should be sanded to leave a smooth and level surface. With plaster walls, any defects should be filled with a joint compound. As the filler dries, it draws together slightly and when dry you should go over the area again until smooth. Larger defects have to be reinforced with joint tape. The crack should be scraped clean and moistened with water. Fill the crack with filler and place the joint tape (very thin fiberglass tape) over the crack in a vertical direction. Now, go over the tape with a thin layer of filler and carefully smooth the filler using the spatula. When the area is dry, you can carefully smooth it with sandpaper.
Once your walls have been repaired they should be cleaned of any sanding residue, grease or obvious stains. Stains may be spot treated with stain killing primer as necessary. Any moldy areas must be treated with a mold remediation solution prior to application of any stain killing primer. Especially difficult stains may require the use of oil-based primers. It is normally recommended to cover these treated areas with an acrylic primer. With the exception of primers that specifically call for sanding of any gloss finish, you are ready for priming.
Preparation for Wallpaper
Experienced wallpaper installers have used different products with outstanding results other than those listed. These guidelines were developed as a starting point for do-it-yourself homeowners and are considered the best guess as to what type of product will suit your needs. This information is based on subjective, collective information from several wallcovering professionals and may not suit your particular application. It is imperative that you fully understand all safety precautions when dealing with these products and always follow the manufacturer’s instructions completely. Follow any instructions from the wallpaper and adhesive manufacturer as to what type of surface preparations are needed for effective bonding.
Any surface you wish to install wallpaper over should be primed with a good quality acrylic primer made specifically for wallpaper.