A surface coating is only as good as the work that went into preparing the substrate, as well as the ambient conditions during the preparation, coating and curing processes. Failure to ensure that the surface coating environmental conditions are ideal could result in improper adhesion of the coat to the substrate, premature failure of the coating, and corrosion. By knowing which factors are essential to the surface coating process, you can take steps control them to your advantage.
Surface Coating Environmental Conditions—What You Need to Know
- Air temperatures: The best temperatures in which to apply a surface coating are between 56°F and 99°F. Lower air temperatures result in delayed curing times, which affect the coating’s performance.
- Surface temperatures: During the day, it is common for surfaces to absorb heat and be warmer than the air temperature. At night, surfaces radiate heat. These changes in surface temperature may lend themselves to the formation of condensation on the surface in question. To avoid problems with coating applications—such as blistering, pinholing and cratering—it is necessary to take into account air and surface temperatures. In general, ideal surface temperatures are between 40°F and 100°F, depending on the dew point, but it is always best to follow the manufacturer’s specifications.
- Relative humidity: Relative humidity levels should be below 85 percent. When relative humidity levels are higher, the conditions may slow the curing process and the solvent’s evaporation rate. While some professionals recommend that relative humidity levels be below 40 percent, it is important to remember that some types of surface coatings require moisture to cure properly.
- Dew point temperature: The dew point is the temperature at which condensation, or moisture, forms on a surface. Problems generally arise when surface temperatures are near the dew point and allow moisture to form on a fresh coating. As a rule of thumb, it is best to not apply a coating if the surface temperature is within 5°F of the air dew point. Ideally, the surface temperature should be at least 5°F above the dew point temperature during all stages of the coating process.
- Wind: Air circulation is important during the surface coating process, but high wind speeds may accelerate solvent evaporation or cause material losses. When applying a surface coating outdoors, wind speeds should be 15 miles per hour or slower.
- Ventilation: Ventilation is necessary to prevent the accumulation of solvents and solvent entrapment, which result in premature coating failures. When applying a surface coating to the inside of tanks or other enclosed spaces, it is a good idea to use a forced ventilation system throughout the coating process and for 48 hours following the final coat’s application.
Most coating failures and coating-related project delays are the result of poor surface coating environmental conditions. While you cannot control the weather at project sites, you can control the ambient conditions surrounding the surfaces that you plan to coat using Polygon’s temporary climate control solutions. These solutions are custom-built for your project and include remote monitoring, allowing you to ensure that conditions remain ideal throughout each step of the coating process. Get in touch with a Polygon representative today to learn more about how temporary climate control will benefit your project.