There are several steps you need to take when you paint brick. First you will need to clean the bricks. Afterwards, you will have to repair the damaged mortar. Then you will need to prime and paint. Neglecting any one of these steps can result in a sloppy looking paint job.
Before you paint brick, you should give the bricks a cleaning. If you do not clean then beforehand, you may end up with a grainy feel to your final paint job or paint that can peel. You will need to clean off any dust, dirt, soot, or anything else that has accumulated on your bricks. To do this, you can use a vacuum or a stiff brush. Your bricks may only need a mild cleaning; however, there are other instances when you will need to do a more thorough job.
In the case of mildew or efflorescence, you will need to do a more thorough cleaning than just dusting alone. Mildew can be taken care of with a mixture of bleach and water. Efflorescence, which results in white stains that are the result of salt deposits on the bricks, is a little more difficult to take care of. It can be removed by scrubbing with water or, if that doesn't work, with the careful application of a more potent cleaning solution as advised by a professional. It is important to note that not all of the stains may be able to be removed; however, if some residue remains, it can often be successfully covered with primer.
The next step you need to take when preparing to paint brick is to repair the mortar. Small repairs can be made with caulk, but excessively crumbling mortar should be looked at by a professional. If you are using caulk to repair the mortar before you paint bricks, be sure to choose one that is approved for masonry and that you will be able to paint over easily. After the caulk is dried, the bricks should be washed and left to dry for about 48 hours.
After repairs are made, select the primer. The one you use when you are going to paint brick should also be approved for masonry. When choosing your primer, you will have several options; some people recommend using oil-based primers, others like acrylic, and still others latex. You may want to ask a professional which option is right for you.
After you've completed these steps, you are ready to paint the bricks. There are several types of paint you can choose from, with a variety of finishes. You can choose the one that matches your home's color and finish. Bricks are porous, so when you paint brick, remember to get a lot of paint — more than you think you will need — and apply as many coats as it will take. You may also consider using a sprayer to ensure even coverage.