How to Spray Texture Onto a Knockdown Wall

Cut out plastic sheeting from a roll to fit over each window and door, but leave one door uncovered. Tape the edges of the plastic around the window and door trim. Open the last door, which you will use to enter and leave the room, and tape plastic sheeting to the door only. Apply more tape to the door trim molding.

Spread drop cloths over the floor. Tape the edges of the drop cloths to the top edge of the baseboards.

Apply more tape along the ceiling where it meets the walls.

Scoop out half the contents of a 5-gallon container of joint compound and put it into an empty bucket, then add 5 pints of water.

Fasten a paint mixing paddle to a power drill. Blend the joint compound with water until there are no lumps, and the mixture is smooth.

Prime the air compressor to 30 psi until it cycles off on its own. Priming means turning on the compressor to pressurize it.

Put on safety goggles and breathing protection. Fill the hopper or reservoir of the paint sprayer with the thinned drywall joint compound. Turn the sprayer tip to the smallest opening.

Stand approximately three feet away from the wall. Squeeze the trigger on the sprayer as you move your arm back and forth, spraying from the top of the wall to the bottom in a zigzag motion. Spray the wall again in an up-and-down zigzag motion to even the coverage. Refill the reservoir before it runs out to keep the flow steady.

Let the walls dry for at least three hours.

Mix a new batch of joint compound for the top coat. Blend half the contents of a 5-gallon container of compound with 3 pints of water, and mix it with the paint paddle.

Prime the air compressor to 15 psi until it cycles off.

Fill the sprayer reservoir with the thinned joint compound, and spray the walls as before.

Wait approximately 15 minutes, then lightly drag the edge of the knockdown knife down the walls, flattening the raised, bumpy texture. Stop before you reach the baseboards. Drag the edge of the knife up the wall from the baseboard to finish the walls.

Let the room dry, which can take 24 hours or longer.

Cut the edges of the painter’s tape, and peel off the plastic around the windows and doors.