Painting Over a CMU Wall That Has Glazing on It

Slip on a pair of rubber gloves and a respirator to create a mixture of one-quarter gallon lukewarm water and one-half tablespoon tri-sodium phosphate, or TSP. Stir the mixture to dissolve the TSP powder, which is a mild-degreaser.

Dampen a kitchen sponge with the TSP solution and wipe down the CMU wall to remove any grease spots, dust and dirt. Wet a separate kitchen sponge with plain water and wipe down the CMU wall thoroughly to remove the TSP residue.

Allow the wall to dry completely before applying a concrete chemical stripper according to the package directions. Many strippers require constant moisture to remain activated, which is accomplished by covering the CMU wall with wet cloths or by spraying it with a garden hose.

Rinse the chemical stripper away with the garden hose before cleaning the wall with a mixture of one tablespoon liquid dish soap and one-half gallon warm water. Dampen a kitchen sponge with the soapy solution and wipe away any remaining chemical stripper residue spots.

Allow the wall to dry completely before covering it with a thin coating of concrete sealer with a paint roller. Allow the concrete sealant to dry completely, or at least 24 hours, before continuing.

Apply a thin layer of masonry primer to the CMU wall. Using a paint roller, create a thin layer of the primer and allow it to dry for at least 12 hours, or overnight, before continuing.

Apply a thin coating of masonry paint to the CMU wall. Once again, use a paint roller to evenly apply the paint. Allow the first coat of masonry paint to dry for at least four to five hours before applying a second, and if necessary third, coat of the paint.