Painting Masonry

There are a number of coating products made for masonry surfaces. These include alkali–resistant primers, masonry sealers, waterproofers and floor paints. In addition to these specially made coatings, common latex paint is a suitable coating for masonry including brick, cinder block and concrete walls.

Alkali–Resistant Primer

Alkali–resistant primers are made using chlorinated rubber and are primarily used on surfaces that have a chronic problem with leaching alkali salts known as efflorescence. Efflorescence is caused by moisture and usually due to drips along a foundation or poor drainage around a building.

Masonry Sealers

Masonry sealers are normally clear and are used to prevent staining, stop sanding debris and to make cleaning the surface easier. The use of clear sealers is particularly helpful for interior exposed brick walls where the look of the natural surface is enhanced while making the wall smooth and debris free.

Masonry Waterproofers

Waterproofers are made by mixing portland cement with a latex paint base to create a thick coating that will block moisture from escaping. These coatings are used mostly on basement and exterior walls. When properly applied these waterproofers will bond with a masonry surface preventing future blistering and peeling. Use two coats on bare masonry and keep the coating moist with a light spray of water for 2 days as it cures. These coatings should not be applied over previously painted surfaces.

Masonry Floor Paint

Masonry floor paints are available in epoxies, urethanes, latexes, alkyds and rubber–based enamels. Of these, the epoxies are the most durable and resistant to abrasion and sub–surface moisture. Urethanes and alkyd based floor paints work well in garages and workshops that see a lot of traffic. For interior basement floors in living areas, latex floor paint will work fine.

Preping Masonry

Let new masonry cure for at least 6 months before coating it with any sealers or paint. This will give the excess alkali salts time to leach from the portland cement. If not allowed to escape these salts will prevent paint from bonding to the surface.

Prep for painting by removing all loose material using a stiff brush like a nylon–bristled scrub brush to go over the surface. If the masonry has been painted before, scrape off any loose or peeling paint with a putty knife. Hose the masonry down if possible and treat any efflorescence bubbling. If you're inside and can't spray with a hose, use a shop vac to go over the surface to pickup any dust. Prime any bare spots with a coat or two of latex or masonry primer and let it dry completely before applying the new paint.

Applying Paint

Painting any masonry material is difficult when trying to get good coverage with the paint coat. Bare masonry is the toughest because it's so porous it sucks up every bit of moisture that comes in contact almost instantly and it will keep absorbing moisture until it is saturated. This can mean that a full roller of paint will not go very far and it requires many coats just to cover a few feet.

Tips for Easier Masonry Painting

To make painting masonry easier try a few tricks. First be sure you have a very thick roller. A nap of at least an inch will be needed to spread the paint into all the little pits and crevices in the masonry surface. When using latex paint, mist the masonry with water just before applying the paint to make it easier to spread. Plan to do two coats on bare masonry to catch all the missed spots rather than trying to cover every inch with the first coat. To improve coverage, a third coat will probably be necessary and will be essential to get a smooth, consistent coat on bare masonry.