How to Remove Paint Off Walls
Scrape off loose and peeling paint, then sand. If the wall is wood or masonry, you can also strip the paint or remove it with heat.
Paint soaks into drywall paper, and while you can scrape a peeling topcoat, it's usually preferable to paint over the base coat rather than try to strip it. You can strip paint from other wall materials, such as wood or masonry, if you want to restore the natural look of the material. When it comes to removing flaking or peeling paint prior to repainting, the procedure for all wall coverings is essentially the same, but you have to exercise more caution with drywall than you do with harder materials. Texturing presents a particular circumstance that requires special handling.
Remove Old and Peeling Paint
Whether or not you plan to strip, the paint-removal job starts with scraping loose paint. Cover the floor with a drop cloth, put on a dust mask and do the job with a 4-inch paint scraper. Use a plastic or flexible metal scraper on drywall and plaster to prevent gouges, but use a rigid metal one on hard surfaces, such as masonry and wood.
Sand the Bits You Can't Scrape
If the paint is in poor condition, you probably won't be able to remove all the small, peeling flakes with a scraper. This is usually a job for sandpaper -- specifically 120-grit sandpaper. Attach a piece to a sanding block and, to make the job easier on yourself, attach the block to a 4-foot pole; using a pole sander allows you to reach the top of the wall without a ladder. Depending on the type of paint you're removing, you may find that the paper gums up quickly -- if so, switch to 100-grit.
Stripping Paint From Hard Surfaces
When you want to uncover a wood or masonry wall for a more natural appearance you have to strip the paint with a chemical stripper. A product that contains methylene chloride works quickly, but you may prefer a soy- or citrus-based product, which is easier on the skin and lungs. Either way, wear protective clothing, rubber gloves and goggles, and keep the room well-ventilated.
Apply the stripper to the entire wall, using a paintbrush or roller. Make sure the stripper covers every bit of paint -- if you leave some uncovered, it won't come off when you remove the stripper.
Wait for the paint to bubble up. This is the sign that it has loosened its hold to the substrate. If the stripper dries out before this happens, apply more stripper.
Scrape away the stripper and the paint with a rigid metal paint scraper. When scraping wood, always scrape with the grain to avoid making cross-grain scratches that you have to sand out.
Remove the residue by washing the wall with clear water when you're done. You may have to scrape parts with a scrub brush.
About Textured Walls
It's difficult -- if not impossible -- to scrape or sand paint from a textured wall without damaging the texture. The best course of action is often to scrape the texture off with the paint, using a drywall knife. Sand and prime the bare drywall, apply a new texture, prime again and repaint.
When scraping or stripping paint from a the walls of a house that was built before 1978, there is a good possibility of encountering a layer of lead-based paint. If you suspect this, remove a chip and test it. If it tests positive, extra precautions must be taken to prevent dust from circulating in the house. Hire a trained professional to do the job.
If the wall is drywall or plaster, sanding is usually the final paint-removal step. If patches remain that create an irregular surface on the wall, you can either smooth the surface by skim-coating the wall with drywall joint compound or apply a camouflaging texture before repainting.
You can remove some types of paint by heating the wall with a heat gun or hair dryer. While this eliminates the need for a stripper it could release harmful fumes, and it's a potential fire hazard. If excessive heat is applied, wood can begin smoldering behind the wall covering, where you can't see it. A better way -- especially for exterior surfaces -- is to use an infrared paint stripper. It loosens the bond between the paint and the substrate without overheating the substrate.
Chris Deziel has a bachelor's degree in physics and a master's degree in humanities. Besides having an abiding interest in popular science, Deziel has been active in the building and home design trades since 1975. As a landscape builder, he helped establish two gardening companies.