The winter months can be pretty tough on commercial vehicles, but especially brutal when the job involves snow removal. Because trucks and equipment are primarily comprised of metallic components, they’re extremely vulnerable to corrosion damage associated with winter weather.
To provide insight on the challenge of winter conditions from a corrosion protection perspective—and to outline a very resilient solution—Jamie Redd, PPG technical sales instruction supervisor, answers a number of important questions in anticipation of the next season of snow.
WHAT CAUSES CORROSION, AND WHAT IMPACT DOES WINTER WEATHER HAVE ON ITS DEVELOPMENT?
REDD: Corrosion is a chemical process through which metallic objects degrade and dissolve to create rust. When trucks and equipment are exposed to excess moisture resulting from rain, snow, ice, and sleet, they’re at an increased risk for sustaining corrosion damage, which can ultimately lead to vehicle and/or equipment failure. Making matters worse is road salt. While it serves an important role in making roads safer for winter travel, road salt creates chemical reactions that speed up the corrosion process. Once the rust starts, it moves very fast.
SNOW REMOVAL TRUCKS AND EQUIPMENT ARE EXPOSED TO ROAD SALT OR OTHER HARMFUL DEICING CHEMICALS WHENEVER THEY ARE IN OPERATION. IS IT SAFE TO ASSUME THEIR METALLIC SURFACES ARE PRETREATED WITH AN ADEQUATE CORROSION RESISTANCE COATING AT THE OEM LEVEL?
REDD: In most cases, the trucks themselves get the same protective coating that standard commercial vehicles receive. However, it is my opinion that trucks exposed to harsh winter road conditions—whether involved in snow removal—would benefit from a coating that contains a greater level of corrosion protection.
Now, if we talk about snow removal equipment specifically, it’s a different story. Snowplows and salt spreaders are often coated with less costly, lower-grade paint applied to metal with little or no undercoating. This amazes me because these components are easily scratched and chipped during use, exposing the substrate and creating the potential for corrosion.
WHAT TYPE OF CORROSION-RESISTANT COATING WOULD YOU RECOMMEND FOR VEHICLES AND EQUIPMENT EXPOSED TO HARSH WINTER CONDITIONS, OR ANY ENVIRONMENT WHERE CORROSION DAMAGE COULD OCCUR?
REDD: For a maximum level of protection, I suggest a corrosion-resistant system that includes a zinc-rich primer. Zinc is a crucial ingredient because it acts as a sacrificial coating that prevents oxygen and water from reaching the steel substrate. Even if the zinc coating is scratched off, it will continue to help protect adjacent areas of the underlying steel by forming a protective coating of zinc oxide.
YOU MENTIONED ZINC AS PART OF A SYSTEM. WHAT OTHER COMPONENTS WOULD THIS INCLUDE?
REDD: Zinc would be your first layer of coating on a bare metal substrate. When using zinc in this application, it’s very common to introduce what is called an intermediate or “middle” epoxy primer. This will add extra protective qualities because it will help keep moisture from reacting to the zinc. You’ll also want to use a high build urethane topcoat and a durable clearcoat. While using a clearcoat is optional, it will enhance the longevity of the substrate and help increase the longevity of the color from an aesthetics perspective.
ADDING A ZINC-RICH PRIMER TO A CORROSION-RESISTANT COATING SYSTEM IS A GAME CHANGER. BUT CAN IT BE DIFFICULT TO BRING ZINC INTO THE EQUATION?
REDD: There are a lot of zincs in the marketplace that can be complicated to work with. For example, a common option is a three-component zinc powder, which includes a curing agent and requires a lot of mixing and intensive agitation during application.
I can’t speak for all brands, but there are less complicated options, such as a system that features PPG ZNP-300 zinc rich primer. This two-component liquid primer is significantly easier to work with compared to a powder-based zinc product. An alternate option is PPG ZNP-101 1K organic zinc rich primer, which is a one-component, ready-for-use product. A rule of thumb in this arena is that fewer components equate to greater simplicity.
WILL THESE ZINC-RICH PRIMER PRODUCTS WORK WELL AS STAND-ALONE PRIMERS?
REDD: Absolutely. When applied to an abraded or sandblasted substrate, both will provide excellent adhesion and outstanding corrosion resistance. But if you’re looking for a highly protective coating package to help maximize the longevity of vehicles and/or equipment exposed to harsh winter weather, consider using one of these two primers as your starting point.
For a middle coat of epoxy primer, I suggest the strong corrosion and chemical resistance of PPG CRE-X21 series primers. Follow this with PPG AUE-370 polyurethane topcoat, or equivalent, and round out your corrosion resistant package with PPG AUE-20 clearcoat, a relatively new, high-gloss urethane clear that provides exceptional durability.
WILL A ZINC-RICH SYSTEM DESIGNED TO PROVIDE A HIGH LEVEL OF CORROSION PROTECTION COME AT THE EXPENSE OF APPEARANCE?
REDD: Again, I can’t speak to all the brands. However, I do know that with this PPG offering, you can get the benefit of extreme corrosion protection plus really good color capability and appearance. The key to this is the middle coat of epoxy primer along with the high-gloss clearcoat.
But I think the single greatest benefit of a complete system like the one I’ve described is the peace of mind knowing that you pretty much have to intentionally blast off the coating to get to the substrate. You’ll be hard pressed to match that level of protection with anything else out there.
About the Authors
John McQuillan is a senior writer for the Group-eX agency and has been covering the automotive industry for more than 20 years.
Jamie Redd is the PPG technical sales instruction supervisor. In this role, he oversees day-to-day operations and leads PPG fleet and commercial coatings training classes at the PPG business development center in Columbus, Ohio. Jamie is also one of PPG’s lead commercial coatings instructors specializing in heavy-duty truck collision repair. Find out more, visit www.ppgpaints.com.
