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Exterior Primer

If you think the choice of primer is not important, Think Again!

Paint failure on concrete wall
Massive failure: 2 Years.

Estimated Wasted Cost to repair: $40,000+

This is a $200,000.00 mural at the Versailles Rd end of Bluegrass Airport in Lexington KY. The surface peeled miserably due to two factors. An improper primer was used that was not tolerant of the high alkalinity (PH) of the concrete surface. The concrete was not properly neutralized before priming. During the fall cooler months, concrete will cure much slower. You can observe how certain panels have cured , while others have not, leading to the unfortunate costly paint failure you see.

We have proven solutions for the most challenging projects.

For new fresh concrete, and even concrete that has weathered, we must get the surface to a neutral ph. We can do this with a simple acid wash, and allow to dry for 3 good drying days.

Unfortunately, a national paint company representative specified the wrong primer for the surface conditions. The concrete was poured in late October and early November, when temperatures dip deeply in the night. The concrete was exposed to low temperatures, and high moisture , and just did not neutralize like it might have in better mid-summer conditions. That highly alkaline surface, combined with apparent backside moisture intrusion, has caused this coating system to fail miserably, and preventively.

Read about Surfactant Leaching.

Read about Cold Weather Painting

This project should have used a primer that was tolerant of any remaining alkalinity, or efflorescence of the concrete. Our products of choice for this similar project would be one of the following:

Coronado 48-11

Benjamin Moore High Build Acrylic Masonry Primer 068

These primers are much more tolerant of that moisture and high alkalinity. . Acrylic primers give much better surface gripping power if the surface is tight and hot (high PH)., as is usually the case with fresh concrete and masonry surfaces.




You must evaluate your specific project requirements when choosing your primer.

"Concrete Block" can be used to describe many different surfaces these days. Newly poured concrete products sometimes can be primed in as little as 15 days with specialized products, and under certain conditions. Masonry curing rates will vary, depending on temperature, air movement, and project conditions. We generally allow at least 30 days, and more is better. We must test the pH of the surface before we can actually say it is ready to coat. Certain coatings will tolerate highly alkaline surfaces, while some will usually fail. So test the pH to be sure, and make sure the coating you choose can handle the surface conditions. Many times a mild to strong acid might be required for any specific project.

You have a couple of options with respect to choice of coating systems. Masonry is a specialized surface, and your preparation of the surface, as well as your coating choice are extremely critical to the success, and long-term durability of your project.

Most standard paints and primers available at Lowes, Home Depot, Sherwin William, Porter, and other mass merchandisers, are not suitable for extreme conditions, and are inadequate to seal the pores of a masonry surface, even with multiple coats. You wouldn't want to use latex paint as a primer. Most latex paint in addition to not tolerating the high pH of stucco, often exhibits pinholes in the coating surface due to the porosity of the stucco. Use a proven system from Coronado, or Benjamin Moore, or other Independent Local Paint Dealer.

For the project featured, consider:

Coronado 48-11 or

Benjamin Moore High Build Acrylic Masonry Primer 068

If the concrete is extremely porous, we might consider first sealing the surface with a siloxane/acrylic emulsion sealer. Siloxane chemically reacts with masonry to form a barrier to moisture intrusion, and serve as a foundation for our finish paint.

On dense stucco, consider a water-based pigmented Elastomeric primer, then 2 coats of the highest quality 100% Acrylic house paint.


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* Pro Tips *
Always prime bare concrete before applying patching or caulking compounds.