For painted concrete masonry to perform well, you must choose the right paint for the job and prepare the surface and apply the paint correctly. WHICH TYPE OF PAINT SHOULD YOU USE? Latex, cement-, oil-, and rubber-based paints are commonly used on concrete masonry. Each type has its own properties and cost. The Portland Cement Association (PCA) suggests considering two things when selecting paints: How will the paint be affected by alkalies (efflorescence)?; How much surface preparation is necessary to apply the paint? WHEN TO PAINT Don't paint new concrete masonry walls before the time recommended by the paint manufacturer. Many painting failures are caused by moisture in the wall. Alkalies in the concrete masonry also can harm some paints. PREPARING THE SURFACE For paint to adhere to concrete masonry, the masonry must be free of dirt, grease, oil, and efflorescence. Remove dirt and dust by air-blowing, brushing, scrubbing, or hosing. BRUSH, ROLLER, OR SPRAY? Architects should specify how each coat of paint is to be applied: by brush, roller, or spray. Some paints should be applied only by specific method; other methods may produce inferior results.