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Two Most Common Methods for Coating Exterior Metals

Posted by Jason Parker | May 12, 2016 10:46:10 AM

2_Most_Common_Methods.jpgA wide variety of ferrous and non-ferrous metal building components are commonly used for structural framing, or as sheets for roofs, gutters, railings and pipes across Florida. Since these materials are prone to oxidation, corrosion and rust especially in coastal climates, they can lose part or all of their aesthetic, performance and durability properties if left unprotected.

To treat and protect metal structures from the harsh environmental factors characterizing Florida, including excessive humidity, heavy rains, high temperatures, strong UV rays and salty marine atmosphere, which can accelerate the corrosion of metals, a series of coating systems and application methods for coating exterior metal have been developed. Read on to discover the most common products and application techniques professionals use to coat exterior metal.

Galvanizing
Galvanizing delivers the most common, effective and economical method for coating exterior metal. The procedure involves immersing steel components into molten zinc at high temperatures (hot-dip galvanizing) or painting them with aluminum-zinc alloys (cold galvanizing) to create a strong and durable bond with the substrate. During the galvanizing process, multiple coatings are usually applied to achieve the coating thickness and appearance desired. Besides the standard pure zinc and aluminum-zinc coatings, other alloy compositions (e.g. the aluminum-zinc-silicon coatings) can be used to provide metal structures adequate corrosion protection in humid environments.

Unlike regular metal paints, galvanized coatings will not fade, crack or debond from the substrate. But since zinc-based alloys corrode, the level of protection a galvanized coating provides is directly proportional to its thickness. In climates that are particularly corrosive, such as Florida’s coastal environment, the common procedure for coating exterior metal involves the application of a thicker coat, which can provide additional corrosion protection.

When freshly galvanized steel is exposed to the environment, it will react with the oxygen, carbon dioxide and water in the air, which will result in several corrosion by-products (e.g. zinc hydroxide, zinc carbonate, zinc sulfate and zinc chloride). These by-products form a thin film on the surface, providing additional protection to the underlying coating system. Since rain can easily wash away this film, which will cause the zinc-based coating to further corrode, re-coating exterior metal periodically is important to ensure adequate protection.

Regular Application
Coating exterior metal often involves the application of high-performance coating systems that can provide the level of protection required. For years, polyurethanes, polyaspartics and polysiloxanes have been successfully used to paint exterior metal, including previously galvanized structures, with a suitable primer applied beforehand.

Brushing, roll coating, air-spraying, airless spraying and electrostatic spraying are some of the standard methods used for painting metal. Besides the type of paint and method of application selected, the weather conditions have a significant effect on the quality and durability of coating systems. For the best results, the temperature and relative humidity should range between 40°F and 90°F and 40% and 70%, respectively.

When all metal surface preparation phases are carried out and the right type of coating is selected and applied adequately, according to specifications, it’s possible to achieve extremely long durability of both the coating system and metal structure, even under the most adverse exposure conditions.

At Performance Painting Contractors, all our coating consultants and painters are certified and highly experienced in coating exterior metal. Not only does this mean they have a thorough understanding of different coating systems; they’re also aware of potential substrate vulnerabilities in marine climates. By knowing how to account for the unique challenges posed by the harsh Florida weather, our professionals are able to recommend the right products for coating exterior metal and produce awesome, long-lasting paint jobs that transform buildings into landmarks. Whether you need assistance with coating selection, cost analysis or performance parameters, we’re waiting for your call at (904)-641-4800 in Jacksonville, FL, or at (813)-308-0388 in Tampa, FL.

Topics: Commercial Painting

Written by Jason Parker

Jason Parker is the owner of Performance Painting Contractors. Priding the company on customer service and professionalism, he brings a new life to the painting industry.

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