Steel is an exceptional structural material, but it has one natural enemy: oxidation. When steel is exposed to oxygen and moisture, corrosion can begin, potentially compromising the aesthetic and structural integrity of the building over decades. At COMSA Steel, our manufacturing process includes a sophisticated coating phase designed to protect your investment from the moment it leaves our shop until long after the building is occupied.

1. The Role of the Standard Shop Primer

The first line of defense for most open web steel joists is a factory-applied shop primer. This is not intended to be a permanent exterior finish, but rather a high-performance temporary shield.

• During Transit: Joists are often transported on open flatbed trailers. The primer protects the steel from road salt, rain, and humidity during delivery.
• On the Job Site: It is common for structural steel to sit staged on the ground for weeks before erection. Our primer prevents “flash rusting” during this critical exposure period.
• Bonding Surface: For joists that will eventually be painted for aesthetic reasons (such as in “open ceiling” architectural designs), the shop primer provides an ideal mechanical bond for the finish coat.

2. The Dipping Process: Total Encapsulation

At COMSA Steel, we utilize a “dip” method for priming rather than a simple spray. Because joists have complex geometries—including the tight interior angles of the chord sections and the contact points of the web members—spraying can often leave “shadows” or missed spots. By submerging the entire joist in a specialized tank, we ensure that every square inch of the steel, including the interior of the joints, is fully encapsulated in a protective layer.

3. Specialized Coatings for Harsh Environments

Standard primer is sufficient for most climate-controlled commercial buildings. However, for projects in high-corrosion environments, COMSA Steel offers enhanced protection:

• High-Performance Epoxies: For chemical plants, indoor swimming pools, or wastewater treatment facilities where humidity and corrosive vapors are constant, we apply industrial-grade epoxies that offer superior chemical resistance.
• Hot-Dip Galvanizing (HDG): For structures that will remain permanently exposed to the elements—such as outdoor walkways or coastal industrial sheds—galvanization is the gold standard. The steel is dipped in molten zinc, creating a metallurgical bond that provides cathodic protection for 50 years or more.
• Cold Galvanizing/Zinc-Rich Primers: An effective middle-ground that offers enhanced galvanic protection without the heat-related distortion risks sometimes associated with hot-dipping very long or light-gauge joists.

4. Low-VOC Compliance and Sustainability

Modern engineering requires environmental responsibility. The coatings used at COMSA Steel are selected for their low-VOC (Volatile Organic Compound) content. This ensures that our manufacturing facility maintains a safe environment for our workers and that the joists do not “off-gas” harmful chemicals once they are installed in a school, hospital, or office building.

5. Field Touch-Up and Maintenance

No matter how well a joist is coated at the factory, the erection process—welding, bolting, and handling—will inevitably cause minor abrasions to the finish. We provide clear specifications for field touch-ups, ensuring that the installation crew can quickly restore the protective barrier at weld points, maintaining a continuous shield against the elements.

By prioritizing advanced coating technology, COMSA Steel ensures that our joists don’t just meet strength requirements today—they maintain them for the entire lifecycle of the building.