How to Paint the Block Walls in a Basement

Examine the surface of the wall for efflorescence, a fine, white, powdery substance. Wash away efflorescence with mild detergent and a stiff-bristle brush.

Scrape dirt and loose grit from cracks with a wire brush. Vacuum away residual dust and debris. Seal the crack with 100 percent acrylic, siliconized acrylic caulk or an epoxy crack sealer. Apply the caulk or sealer according to the manufacturer's directions.

Wash the walls with a mild detergent to remove dirt, grease and grime. Rinse the walls with plain water and a clean sponge.

Mask adjacent areas with low-adhesive tape to protect them from the paint. Place dropcloths on the floor to protect it from overspray, splatters and spills.

Apply a masonry primer with either a high-quality ½- to ¾-inch nap roller or 4-inch nylon/polyester brush to reduce the amount of paint you'll need to use to cover the wall, as well as to protect the paint layer from efflorescence and discoloration.

Apply one coat of flat, semi-gloss or satin finish of a top-quality, 100 percent acrylic masonry paint. Fill every pore and void on the wall's surface. Follow with a second coat of paint. Devote extra care toward covering any pores you missed with the first coat.

Remove protective tape, plastic and dropcloths and discard. Discard brushes and rollers or clean according to the paint manufacturer's directions.