Salt Spray Testing Demonstrates That Galvanized Steel Not a Long-Term Solution to Corrosion on HD Trailer Chassis

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ASTM B117 salt spray testing by Daubert shows that galvanized steel cross members begin to shed protective zinc coating within 1,000 hours of exposure.

galvanized steel I-beam, galvanized steel trailer construction, galvanized steel trailer components

Results of ASTM B117 comparative corrosion resistance testing reveal the limitations of galvanized steel and its inability to withstand exposure to the most common corrosive agent, sodium chloride.

The idea that corrosion can be avoided by building a trailer using galvanized components is a myth. – Mike Duncan, Ph.D.

Daubert Chemical, an industry-leading manufacturer of specialty coatings and adhesives, announced the results of comparative corrosion resistance testing that reveal the limitations of galvanized steel and its inability to withstand exposure to the most common corrosive agent, sodium chloride. In salt spray exposure tests following American Section of the International Association for Testing and Materials (ASTM) B117 standards, Daubert compared galvanized steel I-beams to I-beams coated with Daubert’s Nox-Rust 1210HP wax-based coating.

Daubert Chemical Company is a recognized leader in the formulation of cavity wax and wax-based underbody coatings. Nox-Rust 1210HP is considered the industry’s leading corrosion-inhibiting solution for medium- and heavy-duty truck and trailer manufacturers. The company performed the experiment in response to its OEM customers’ inquiries regarding the viability of galvanized components in trailer chassis construction.

“Questions about the use of galvanized steel chassis components have arisen among truck and trailer OEMs in recent years,” Mike Duncan, Ph.D., vice president technology for Daubert Chemical, said. “As we discussed the topic with our customers, we realized that nobody had done a definitive study on the subject, and that’s when we decided to undertake formalized testing.”

Also known as salt fog testing, the ASTM B117 is a standardized method used to assess the corrosion resistance of various surface coatings and is often used in side-by-side comparisons that demonstrate the relative effectiveness of different coatings. Salt spray testing is an accelerated corrosion test that approximates the long-term protective efficacy of a coating and is equally effective at predicting its failure rate.

The test results showed that after 1,000 hours of exposure to the saline spray, the galvanized steel I-beam underperformed in comparison to the I-beam coated with Nox-Rust 1210HP wax-based coating. The continuous salt spray exposure caused the galvanized sample to begin visibly shedding its protective zinc coating in the form of zinc oxide, also known as white rust.

The zinc coating used in the galvanizing process is known as a sacrificial anode because it corrodes first, in preference to the metal substrate it is designed to protect. In contrast, a wax-based coating like Nox-Rust 1210HP is hydrophobic and repels water molecules, preventing the oxidation that can be caused by moisture contacting the metal beneath its protective layer.

Using galvanized metals for trailer construction presents other problems as well. Galvanized steel is only protected as long as the zinc coating is in place. Trailer assembly processes, such as attaching landing gear, slider suspension boxes, wing plates, lighting brackets and the like, often includes welding, grinding and drilling operations that can dislodge the zinc coatings on galvanized steel, causing hazardous particulate matter to become airborne. Once the protective zinc is removed, the steel substrate is vulnerable to corrosion due to both oxidation and galvanic reaction from contact with dissimilar metals.

In contrast to galvanization, the Nox-Rust 1210HP coating is self-healing. With Nox-Rust, a residual anticorrosive barrier of the wax-based material is retained even after machining of pre-coated stock has taken place. The Nox-Rust coating is also available as a touchup solution that can be applied to areas where the coating has been significantly disturbed in the assembly process. Nox-Rust 1210HP also adheres to fresh welds and provides residual oxidation and galvanic suppression during the application of screws, bolts and other mechanical fasteners.

“The idea that corrosion can be avoided by building a trailer using galvanized components is a myth,” Duncan said. “You simply can’t take corrosion out of the equation with galvanized steel, but you can successfully manage corrosion on all exposed metals, including galvanized, very cost-effectively with hot-melt wax-based coatings like Nox-Rust 1210HP.”

Details, specifications and product information for Daubert’s entire range of corrosion prevention coatings, industrial anti-skid coatings, sound deadening coatings and specialty adhesives are available at

About Daubert Chemical Company
Since 1935, Daubert Chemical Company has focused on being the industry’s “silent partner” as a provider and supplier of corrosion prevention coatings, industrial anti-skid coatings, sound deadening coatings, specialty adhesives, as well as concentrate formulations to service the aerosol packaging industry. Daubert takes great pride in its ability to work with its customers in the steel, automotive, transportation and general manufacturing industries to develop optimal solutions for their applications. Working in tandem with laboratory personnel in Chicago, our sales consultants champion the customer’s products by identifying unique application requirements that, in turn, result in selecting the right formulations. From the laboratory to the customer’s location, we do it all quickly and cost-effectively. Learn more at

Nox-Rust is a registered trademark of Daubert Chemical Company.

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