There are special considerations for coating concrete and masonry surfaces. This article goes over the basics and provides videos and links to learn more.
When new, existing or compromised concrete is your substrate, a wide variety of factors will determine the long-term success of your coatings project. And long before choosing a coating comes analysis of the surface and understanding the job your coating will perform.
For example, will a coated concrete surface bear heavy traffic (foot or otherwise), or face frequent abrasion or wind-driven rain? What’s the environment like? Will it encounter variable temperatures? Will it be exposed to high levels of moisture or frequent chemical cleaning?
Here are three steps to success in any concrete coating project, according to the product and application experts at Sherwin-Williams:
1. Assess the substrate
An existing finished concrete surface can offer a variety of clues as to the problems that may be linked to a previous coating application issue.
For example, white powdery deposits on the surface of masonry can indicate that salts and water were drawn out of the masonry. A proper application – in which a recommended coating is applied where needed at temperatures and specifications defined by the manufacturer – will likely leave no path for the migration of moisture and salts.
Peeling, sagging paint is a likely result if wet walls were painted, or if the walls allow moisture to migrate through regularly.
Pinholes in the film could result from outgassing during application, improper application, or painting over contaminants. This can be prevented with proper planning.
Water or rust staining on a coating surface can indicate a flow or pooling problem that may need to be corrected before coating. You may determine at this point that a concrete repair is needed before any coating gets under way.
The substrate will define your coating needs and give you specific information about how to deliver a successful application.
2. Consider the coating solution
Once you have an idea of the substrate condition, you’re ready to take a deeper dive into creating a solution, and here’s where you’ll determine a coating that meets your needs.
For example, will chemical or abrasion resistance that a heavily trafficked basement floor might endure be key features in a finish? What about aesthetics preferred by a homeowner and overall longevity? How about keeping wind-driven rain out of the building?
The application environment warrants consideration as well. What’s the temperature and humidity? Will others be working in the area? Is it well-ventilated? Does the owner (or other stakeholders) have expectations of a quick return to service?
The nature of coating concrete often results in the delivery of custom coating solutions. Having a proper plan that defines product needs is an important step. Sherwin-Williams has products that deliver, plus the experts who can guide your product selection and application.
3. Restore and prepare the surface
By now, you will have determined if the project requires a repair or treatment before a coating application would begin. But if it’s time to apply a coating, perhaps the most important step is what you do next.
Surface prep is 90 percent of what determines whether an application will succeed or not, and the information you’ve gathered so far will determine whether the preparation will include, for example, chemical cleaning, acid etching or abrading. Proper bonding and adhesion of any repair or protection system depends on proper surface prep.
Provided surface preparation has been appropriate, the coating system you’ve chosen for the specific demands of the project should provide long-lasting protection and performance.
This article was published in the Spring 2022 issue of PPC magazine. Photography by Mike Starling, PPC Editor. Read more stories about paint products and application in the PPC magazine archive.