How to Fix Bumpy Walls

Mix powdered topping compound in a bucket or open a container of premixed topping compound. This is a light type of joint compound that drywallers use exclusively for top-coating. If you mix your own, add the powder to water, stirring continuously with a stir stick until it becomes just thick enough to stay on an upside-down drywall blade without falling off. Be sure the mixture is free of lumps.

Transfer a quantity of topping compound to a hand-held trough with a 4-inch paint scraper. Load the mud onto a 10- or 12-inch drywall blade and spread it on a section of the wall. When you have covered the entire section, scrape the blade lightly over the surface to flatten it. Transfer the excess that you scrape off back to the trough.

Scrape as much as possible in long, straight strokes, letting the blade ride over the bumps while the mud fills in the spaces around them. Don't try to cover the bumps in the first coat. You'll get the best results by spreading two or more thin coats. When you have finished scraping, do the other sections of the wall in the same way.

Let the first coat of mud dry for 12 to 24 hours or until it turns a uniform whitish gray color. Spread a second coat in the same way. Let that coat dry, then spread a third coat if necessary.

Attach a piece of 120-grit sandpaper to a sanding pole and lightly sand the final coat to remove any ridges or other imperfections.