Like frosting on a cake, a pallet rack isn’t complete without a layer of protective coating or finish applied to its uprights and beams. While there are a handful of options available, the trick is to select the one that best suits the material handling application. That makes understanding the different pallet rack coating and finish options essential.
“There are four primary kinds of finishes and coatings used on industrial steel storage rack. They include paint, powder coating, galvanized, and zinc plating,” said Jonathan Hirst, Vice President and General Manager at North American Storage. The company is a member of the Rack Manufacturers Institute (RMI). “Also, while the terms are often used interchangeably, a coating is generally a material that is deposited on the rack, while a finish is usually applied.”
One of the most critical factors when choosing among the four types of rack coating and finish options is the facility’s environment. Different storage environments call for different finishes, Hirst noted.
“Rack installed outside or in a high-humidity operation needs a different finish than a system used in ambient temperatures. Facilities handling packaged food need a different coating than those processing raw ingredients,” he explained. “It’s important to specify the finish that will best preserve the rack components’ integrity.”
Paint Finishes Offer Endless Color Varieties
The least expensive option, paint is also the most common pallet rack finish. It’s frequently used in ambient warehouses and in low-humidity freezers. Because a paint supplier can affordably blend virtually any shade, a rack buyer can specify colors beyond the rack manufacturer’s standard color palette.
“It’s becoming more common for companies to specify rack paint colors that match their corporate branding,” noted Hirst. “Now that warehouse photos are appearing more often in corporate literature and annual reports, major corporations are specifying custom rack paint colors.”
To apply a standard color to the rack, the manufacturer dips the formed components into a vat of the wet paint. After the excess paint drips off the beams and uprights it air dries. The rack coating is so thin, however, that it doesn’t disguise surface imperfections. It’s also the finish most likely to chip.
“That might be beneficial, however, in that chipped paint can make rack damage much more obvious and easier to spot,” Hirst said.
Some operations specify different rack paint colors to enhance associate awareness and safety. Racks or bays painted a specific color can indicate a configuration with a heavier load capacity, for example.
“Also, installing beams of a different color in the last bay at the end of an aisle provides a visual safety cue of an intersection ahead,” added Hirst. “Applying a highly visible color to cross-aisle ties makes them easier for forklift operators to see—and avoid—as they’re handling high elevation loads.”
Powder Coating Creates Layer of Plastic Film
Powder coating uses either compressed air with an electrostatic charge to deposit finely ground particles of pigment and resin on rack components. Heat then cures the powder, melting it to form a uniform plastic film coating.
“Powder coating is very smooth and a little thicker than paint. It’s also more expensive to apply,” said Hirst. “Powder coating is more durable than paint, and resists cracking, peeling, scratches, and rust.”
Because of its durability, light-duty retail and freezer applications often use powder coated racks. Also, in unpackaged food processing applications—where ingredients might contact the storage system—food safety certified powder coating formulations can be used.
“Companies that want to pick specific colors for their rack coating may not get the precise match they hope for with powder coating,” he noted. “Because it’s a blend of pigments and resins, it’s difficult to create an exact shade. Also, the steel itself—whether its structural or roll-formed—can affect the shade of the color after heating in the oven.”
Hot-Dipped Galvanized Rack Coating Resists Corrosion, Rust
For maximum resistance to rust and corrosion, hot-dipped galvanized rack coating is the optimal finish. In this process, the manufacturer dips the steel rack components into a vat of molten zinc. The zinc bonds chemically to the steel, creating a heavy-duty layer of protection.
“The zinc coating covers the components both inside and out,” explained Hirst. “Zinc prevents the steel from rusting, even if it scratched through to the bare metal.”
That degree of durability makes hot-dipped galvanized the coating of choice for rack installed in harsh outdoor environments. It’s also ideal for use in wet, high-humidity spaces indoors, such as refrigerated warehouses and coolers.
“In food processing facilities that require sanitary washdowns or handle corrosive ingredients like spices, hot-dipped galvanized rack coating is the best defense against rust,” he added.
Thinner Zinc Plating Rack Coating Also Resists Rust
Zinc plating of rack components also deposits a layer of protective zinc onto the steel. This process uses an electrical current—known as electrochemical deposition—to bond the zinc to the steel, but in a much thinner layer than hot-dipped galvanizing.
“Zinc plating is a lighter duty finish than galvanized, yet still offers corrosion and rust protection,” explained Hirst. “It is often used on roll-formed rack components, or wire mesh rack decking. It’s a great rack coating alternative to paint for lighter duty outdoor applications. It’s also ideal for rack next to transient areas like a wash bay or a dock door that opens and closes year-round.”
Discover More Rack Best Practices
Want to learn more about best practices in installation, use, inspection, and repair of industrial storage rack systems? RMI offers multiple resources detailing both standards and best practices that enhance people and pallet rack safety. This includes a series of videos, presentations, publications, case studies, frequently asked questions, and an MHI Cast podcast recording about rack safety.
