Alternatively, you can mix the masonry cleaner with water in a 1-to-1 mixture in a pressure washer and clean the surface of the cinder blocks with the pressurized mixture. To avoid future deposits after painting, locate the cause of the leak and repair it appropriately before priming and painting.
Don’t worry about very small pieces that are still present after you remove most of the paint. You can normally scrub these off with water or paint over them without any problem.
Avoid using soap in the water because it will take longer to dry and isn’t effective for cleaning bare cinder block.
Be patient. If all of the blocks aren’t dry after 48 hours, you should wait a couple more hours before priming. [6] X Expert Source Andre KazimierskiPainting Specialist Expert Interview. 26 January 2022.
For a smooth finish, run a razor over the applied caulk to flatten the joint and make it blend with the rest of the block. You can also use this method to seal cracks between individual cinder blocks and protect against water leakage.
If you’re painting an area that has a water leakage issue, such as a basement, or painting blocks that are located outdoors, look for a waterproof primer. Bonding and filling primer will work for both smooth and split-face cinder blocks. Make sure you measure the height and length of each wall, and add the areas of each wall to find the total that you’ll be painting before you go to the store. Then, ask the sales associate for a recommendation on the amount of paint you should purchase based on the area. [10] X Research source
One coat of primer will be plenty if you’re painting over with a different color. If you’re only priming the blocks, a second coat will ensure the paint sticks and prevent wear over time.
To determine how much paint to buy, use the same area measurements that you used to purchase the primer. Ask a store associate how much paint they recommend for the area, which will vary based on the brand. At the hardware store, purchase a half-gallon of extra paint in case you need to touch up the paint in the future. If the paint will be on exterior blocks, select a paint that is also weatherproof to prevent damage from the elements.
Try to avoid overlapping sections, as these will take longer to dry and can give an uneven look to the first coat. If you have smaller areas that need to be painted, use a nylon polyester brush.
If you live in an area that’s more humid, you might need to wait up to 18 hours before the paint dries.
For hard to reach or tight places, you can use a brush, but your brush strokes may be visible on smooth cinder blocks.
If the second coat isn’t even or you want better coverage, you can apply a third coat to the blocks. Be sure to wait at least 12 hours before applying a third coat.
