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Understanding Climate Control and Its Effect on Coating Project Outcomes

WEDNESDAY, FEBRUARY 28, 2018

By Russ Brown, Polygon Group


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. Most coating manufacturers’ coatings data sheets recommend ideal conditions in which to apply their coatings. If the temperature is too high or too low, the coating can be subject to curing issues, proper wetting out of the coatings material and adhesion problems.

Condensation, temperature extremes and curing problems can lead to expensive delays, the need for rework and warranty repair costs that can affect the overall service life of the project. In theory, if all is done in accordance with the manufacturer's specifications for application and environmental controls, the coating will provide a long, productive service life. By knowing which factors are essential to the surface coating process, you can take steps to control them to your advantage.

Photo: Shutterstock

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. Typically, 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.

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.

Generally, 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 you plan to coat. Polygon's temporary climate-control solutions are custom-built for each project and include remote monitoring, helping you ensure that conditions remain ideal throughout each step of the coating process.

The benefits to utilizing temporary climate-control equipment fall into two categories: cost savings and quality assurance.

Cost Savings. Controlling the climate during blast-and-coat cycles can reduce man hours, waste and the number of days needed for rental equipment, improving productivity and significantly lowering cost. Creating conditions that will limit corrosion also has a direct impact on the overall cost of the project, which easily justifies the use of temporary climate-control equipment. The cost comparison of a tank project with temporary dehumidification and without dehumidification shows a 10 percent reduction in cost when using the additional climate control. The shorter production time also yields a cost savings for the contractor.

Quality Assurance. The second benefit, and possibly the most important, is one of improved quality. Temporary climate control will provide the perfect conditions for enhancing the blasting, application and curing of the products being applied. It can reduce the spikes caused by regular fluctuations from fast-moving weather patterns or day-to-night transitions. In essence, if the coating is applied to a well-prepared surface at the right temperatures for application and curing, one can expect a system with a longer life expectancy. Additionally, a better-applied system may lead to less warranty rework, which can negatively impact the profitability of a project.

One final thought: To fully understand how moisture might affect the blasted steel, it is important to understand psychrometrics, the science of moisture in air. When engineering a moisture-control method, psychrometrics can predict, with certainty, the conditions under which the dew point temperature or condensation will create a potentially costly situation at a job site. The use of psychrometrics will allow the contractor to make critical projections and decisions, such as identifying specification-related issues, determining when to stop blasting and protect the work, or forecasting conditions for blasting and coating.

*Claims or positions expressed by sponsoring authors do not necessarily reflect the views of TPC, PaintSquare or its editors.

 

ABOUT THE AUTHOR
Russ Brown, Polygon Group

Russ Brown is sales director, Strategic Alliances, for Polygon and is based in Indianapolis, Ind. He has worked in coatings for 35 years — 22 for Polygon. Currently, he develops and implements strategies to expand Polygon's core coatings-related services in North America. Brown has a BS in liberal arts and sciences from the University of Illinois. He was on the board of governors for the Society for Protective Coatings (SSPC) and served as its president in 2011.

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