Why Temperature & Humidity Matter in Commercial Coating Projects

We've said it before, and we will probably say it again - Temperature and Humidity matter in every commercial coating project. Even with the best equipment, the best training, and the best application technique, these two key factors will make or break your application and can lead to costly re-do's, repairs, or even lost customers. Join us as we walk you through the "whys," so you are armed with the imperative knowledge you can pass along to your crew and customers regarding commercial coating application and customer scheduling.

Environmental Monitoring:

Environmental monitoring in commercial coating applications is the systematic measurement of environmental factors—temperature, humidity, dew point, and surface conditions—before, during, and after coating application to ensure proper adhesion, curing, and longevity. Technologies now allow for real-time monitoring of multiple job sites from a single dashboard, reducing manual inspection time and costs. Environmental monitoring also ensures that the coating system is applied within its designed window, resulting in a durable, high-quality finish, rather than a failure that necessitates expensive rework.

Some Tools Used are:

• The Weather App: Air Temperature is a major influencer of drying times and curing rates, while Wind and Precipitation need to be monitored to avoid contamination and ensure proper curing during exterior applications. These are all available for both current and provide a rough estimate of conditions as far out as 15 days. This is a great tool for scheduling your customers.
• Digital Psychrometers: These measure relative humidity and ambient temperature. (RH) levels should generally be below 85% to prevent moisture entrapment.
• Surface Thermometers: These measure the surface temperature of the substrate. Surface Temperature is crucial for coating adhesion, generally required to be between 40°F and 100°F, depending on the product.
• Dew Point Meters: These will calculate the dew point automatically. The surface temperature must be a safe margin, which typically is 5° degrees above the dew point to prevent condensation on the substrate. Remember: "The 5-degree Rule."
• Wet Film Thickness Gauges: These ensure the correct amount of coating is applied while still wet. Applying too thick a layer between applications can lead to a tacky texture, improper curing, and having to repair and reapply.
• Data Loggers: These provide automated and continuous documentation of conditions for reports and audits.

Environmental Controls:

Can you really control the weather? No, but you can take actions to have a sense of environmental control in the direct area where you will be applying the commercial coating of your choice. What is the HVAC availability on site? Environmental controls can include adjusting the HVAC system to have a semi-set atmospheric temperature. No HVAC - that's okay - you can also utilize fans to promote air movement and circulation at the worksite. Is the work site too humid, or is rain expected in the next couple of days? Commercial Dehumidifiers can be scheduled at the work site before and during the application to assist with the removal of the excess humidity. Commercial dehumidifiers typically remove between 100 and 300+ pints (12.5 to 37.5+ gallons) of water per day (PPD), with high-capacity industrial units capable of exceeding 700+ PPD in extreme conditions. This can drop your humidity levels from 80% and 90% all the way down to 30%-50% in a short amount of time.

Coating Issues:

Several coating issues can arise, caused by high humidity and/or Lack of Temperature control. They include, but are not limited to, the following:

• Blushing/Amine -Blushing in commercial coating applications is a surface defect characterized by a milky, cloudy, or hazy white appearance, often accompanied by a waxy, greasy feel. It is essentially a surface contamination resulting from moisture reacting with the coating, most commonly occurring in epoxy systems (as "amine blush") or in lacquer systems due to solvent evaporation. This phenomenon acts as a bond breaker, leading to serious, costly failures in adhesion between subsequent coats.
• Orange-Peel - The name orange peel is given by the resemblance of the final paint finish to an orange peel. This problem is caused by the lack of stretching or levelling of the paint, resulting in a deformed surface and an increased thickness of the final coat. This can be caused by various reasons, but the most common is using a reducer/thinner that evaporates too quickly for the environmental temperature, causing the paint to dry before it can level out. You will see this in too high an ambient temperature or in low-humidity situations.
• Trapping Solvent - this is a coating defect where solvent molecules become locked within a curing coating film instead of evaporating into the atmosphere. This occurs when the surface of the coating dries or "skins over" too quickly, trapping the liquid solvent underneath before it can escape. Some common causes of this are High temperatures or improper use of "fast" thinners, and high-speed curing can cause the surface to seal prematurely. Cold, damp conditions can also prevent proper solvent release.
• Poor Adhesion - Poor adhesion in commercial coating applications is primarily caused by inadequate surface preparation (over 60% of cases), including contamination and improper surface profiling. Other major factors include incorrect environmental conditions, such as high humidity, and uncontrolled temperature fluctuations during application
• Flash Rust - Flash rust is a thin, powdery layer of iron oxide that forms rapidly on metal surfaces after wet abrasive blasting, water jetting, or chemical stripping. It is caused by high humidity, moisture in the air, or using water-based coatings on metal surfaces. If not managed, it leads to poor coating adhesion, premature coating failure, and costly rework.

Today, we discussed the reasons why temperature and humidity control matter during each commercial coating application. Even within the same geographic region, each application can vary. While these monitoring techniques can be utilized, it is also a best practice to consult your specific product's Technical Data Sheet (TDS) to ensure that you have the most exact requirement for the application chemicals being utilized. This will make sure that your customers' commercial coating application has the best possible outcome, post-curing resulting ultimately in overall customer satisfaction, word of mouth referrals, and increased trust in your business. Who doesn't like a little bit more spending money in their pocket at the end of a busy week?

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