How to Put on a Skim Coat

Wipe off the surfaces of the walls that will receive the skim coat. Use plain warm water and a large sponge. Do not saturate the wall.

Clean out and loose material from the inside of any cracks, using a dry paintbrush. Fill in deeper cracks with joint mud and place drywall tape over all the cracks, using joint compound to secure the drywall tape.

Tape off any woodwork or other trim using blue painter's tape.

Fill the long mud pan with all-purpose joint compound. Use it full-strength. Scoop up a blob of it with a broad knife and begin applying it at the top of the wall. Work your way down to the bottom and move on to another section. The first coat is to put a layer of mud on the entire surface.

Hold the broad knife nearly flat and knock off any large chunks or raised areas of all-purpose mud on the wall.

Apply a second skim coat of all-purpose joint compound, following the manufacturer's recommended curing time. Fill in any rough or low-lying places that the first coat didn't fully address. Knock off any high spots when the second coat is almost dry.

Apply a third coat, if needed, to smooth the wall's surface texture. Allow the final coat to dry thoroughly, as recommended by the manufacturer, before proceeding to the next step.

Sand the skim-coated walls thoroughly, using a fine-grit sanding sponge. Sand lightly; don't introduce more irregularities than you are eliminating.

Apply one to two coats of drywall primer/sealer using a paint roller before painting the decorator color or hanging wallpaper.