How to Mimic Knockdown Texture

Put on gloves. Pour drywall mud into a bucket and add one or two cups of water.

Install a drywall mixing blade into a power drill. The mixing blade has a long shaft whose end you insert into the drill's chuck.

Mix the water and drywall mud to a consistency that matches the knockdown texture already on the wall or ceiling. Add more water as necessary. Mix until the mud is thin but not runny.

Dip the bristles of an old whisk broom into the thinned mud. Place a plastic sheet on the floor and place a piece of cardboard on it. Hold the broom bristles in front of the cardboard. Press your hand against the bristles to force them back, and release so the bristles fling the mud onto the plywood. Determine if the mud consistency matches that of the texture already in place. Continue mixing the mud and testing it on the cardboard until it does.

Dip the bristles of the whisk broom into the mud again and hold them in front of the smooth patch on the ceiling or wall. Press your hand against the bristles, forcing them back, and release, flinging mud onto the drywall.

Wait 10 to 20 minutes for the mud to set.

Skim lightly across the mud with a drywall taping knife. Hold the taping knife at about a 45-degree angle to the surface, and knock down, or flatten out, the peaks in the mud. Wipe excess mud from the taping knife as you work, using a wet sponge.

Allow the texture at least 24 hours to dry completely before you prime and paint it to match the surrounding texture.