Painting Concrete and Masonry Surfaces
You can use a fresh coat of paint to bring new life to an old basement, an exterior masonry wall, brick, or even a garage floor. With proper preparation, painting surfaces like these can be simple, and the end result will be worth the effort.
Step 1 - Clean the Surface
As with most painting projects, preparation is the biggest key to your success. If at all possible, power wash the surface first. This is the fastest and easiest way to remove old paint and any debris that will interfere with new paint. Use the power washer with some bleach or mildewcide if there is mold or algae present. However, you may be working inside, or in a place where the mess of a power washer isn't appropriate. If that’s the case, tackle cleaning with a scraper and a wire brush instead.
After all of the loose paint and debris has been removed, make sure that the substrate is clean. Any oil or grease on the masonry surface will bleed through the paint, causing discoloration, and possibly interfering with the longevity of the paint job. Use tri-sodium phosphate, also simply known as TSP, to clean the concrete surface before applying any product. Put on safety goggles, gloves, and a face mask; then, mix your TSP cleaner in a bucket according to the manufacturer’s instructions and scrub it onto the surface with a scrub brush to remove any grease or oil and ensure that your paint will stick well.
Step 2 - Make Any Repairs
If you have any defects in the surface to repair, use a simple, ready-mix concrete patch to fix them after you clean. Refer to the manufacturer's recommendations when trying to assess how long the patch should dry before being painted.
Step 3 - Select Your Paint
When choosing your paint, the most important thing to keep in mind is location. Where is the paint going to be applied? When you’ll want to use interior over exterior paint—or vice versa—is fairly self-explanatory. Many manufacturers actually do make specific masonry paints, and some are even designated as floor paints, so you shouldn't have a hard time finding what you need if you pay attention. There are also additives for your floor paint that can give it some texture or grip. This material is inexpensive and doesn't change the color but does prevent the slips that can occur when wet feet hit a slippery floor. Some kits also come with decorative chips that are added as the paint is applied.
If you are using an oil-based paint and primer, you will need mineral spirits or paint thinner to clean your brushes, and most likely yourself.
Step 4 - Seal and Prime
Almost any masonry surface needs to be both sealed and primed before the paint is applied. The sealer is often clear, but keeps moisture from coming through the concrete. This is especially true in basements, which tend to hold moisture anyway. If you are not sure whether your basement has been sealed or not, tape all four sides of a square of plastic kitchen wrap onto the floor and leave it for 24 hours. If the floor hasn't been sealed, you will see condensed water between the plastic wrap and the floor that has evaporated up through the concrete. Check with a paint store or your local home improvement store’s paint department when selecting your products. Buy a quality masonry sealer and a primer that complements it. Use the two-step process of sealing and priming to build a strong, water-resistant foundation for your paint.
Step 5 - Paint the Surface
After your sealer and primer coats are completely dry, apply the paint. Use a paint brush to do detail work such as around windows and trim or baseboards. You also need a brush for cutting in along the walls when painting a floor. A roller can be used to do the bulk of the painting, but make sure to read the manufacturer's recommendations as to what size nap to use. At least 3/4-inch or one-inch nap is recommended. Buy at least three roller covers, one each for the sealer, primer, and paint.
Apply several thin coats, rather than trying to apply one very thick coat, as paint actually forms a harder surface when thin coats are laid on top of each other. One thick coat often results in a gummy or soft surface. Allow each coat to dry thoroughly; this is often called “curing.” It means that the paint has dried through all the layers down to the original surface. Paint dries to different thicknesses, or “mils,” depending on its sheen and makeup. The thicker the mil of the paint, the longer this process can take. Paint applied to floors or walls in basements may have a longer curing cycle.
After your final coat of paint is applied, allow the paint to cure for the recommended time. If the paint is on the floor and you don't let it dry long enough, it may dry with footprints that will never go away.
Painting a masonry or concrete surface, be it walls or floors, inside or out, can give new life to your home. A space that may once have been dank and dirty can now be bright and clean. You can actually increase the amount of livable space you have just by adding some paint.