Reducing Time and Cost with Polyaspartic Urethanes


By Bruce Toews, Sherwin-Williams Protective & Marine Coatings

Productivity is paramount on coating projects so contractors can protect their customers’ bottom lines. The faster crews can complete a coating application, the sooner that asset can be moved to its next stage of production or put back into service. Fortunately, applicators can accelerate project schedules by using coatings offering fast cures, low-temperature applications, wide recoating windows, and more. However, nothing can fast-track a coating project’s turnaround more than eliminating an entire application layer.

For more than a decade, polyaspartic urethane systems have allowed shop and field applicators to do just that—skip an entire coating layer—without sacrificing performance. Conventional two- and three-coat polyurethane systems often feature a zinc-rich primer or an epoxy as their base layer, topped with one to two additional coating layers to enhance aesthetics and durability. Advanced polyaspartic urethane systems, however, exclude one of those layers, while delivering corrosion resistance, edge retention, and color and gloss retention properties that rival—and can even exceed—those of traditional systems. Dropping this full application step can result in notable efficiency gains and cost savings related to reduced labor needs, fewer opportunities for mistakes, and decreased weather delays.

The high film-build characteristics of many polyaspartic urethanes deliver the required thickness and durability that was once only possible with an additional coating layer. The coatings can either be applied direct-to-metal (DTM) or as a two-coat system replacing a three-coat system—eliminating one coating application in either case. The coatings are also commonly fast to dry and cure, which further accelerates applications by allowing crews to handle, transport, and install coated assets sooner.

Let’s review some additional ways reduced-coat, faster-turnaround polyaspartic urethane systems outperform their traditional counterparts—and how applicators can enhance customers’ satisfaction by delivering coated assets sooner and/or reducing facility maintenance downtime.

Accelerating Shop Throughput

In a shop environment, fast-curing, reduced-coat polyaspartic urethane systems offer unmatched productivity gains. Due to the systems’ short dry-to-handle times, applicators can realize wait-time reductions of over 75 percent—whether shifting from a three-coat to a two-coat system or from a two-coat to a single-coat, DTM system (see Tables 1 and 2). This fast-curing capability greatly reduces grit and dust pickup for better aesthetics, while also accelerating shop applications by allowing crews to handle, transport and install coated assets sooner.

Table 1. Wait-Time Comparison for Three-Coat vs Two-Coat Systems

Conventional Three-Coat Zinc/Epoxy/Polyurethane System Two-Coat Zinc/Polyaspartic System
Polyurethane Topcoat 6 hours to handle 2 hours to handle Polyaspartic Urethane Topcoat
Epoxy Intermediate 8 hours to recoat
Organic Zinc-Rich Primer 2 hours to recoat 2 hours to recoat Organic Zinc-Rich Primer
Total Time Waiting 16 hours 4 hours (75% time savings) Total Time Waiting

Table 2. Wait-Time Comparison for Two-Coat vs Direct-to-Metal (DTM) Systems

Conventional Two-Coat
Epoxy/Polyurethane System
Direct-to-Metal (DTM) Polyaspartic System
Polyurethane Topcoat 6 hours to handle 2 hours to handle DTM Polyaspartic Urethane Coating
Epoxy 8 hours to recoat
Total Time Waiting 14 hours 2 hours (86% time savings) Total Time Waiting


Polyaspartic urethanes offer dry-to-handle times as low as two hours, enabling high-throughput shop applications to go even faster.

Boosting Productivity in the Field

For field applications, polyaspartic urethane systems enable much faster turnaround with lower costs. The reduction of a complete application layer is a primary factor in these efficiencies. In addition, the systems’ fast-drying characteristics facilitate faster returns to service and reduced downtime. Further aiding efficiencies in the field, polyaspartic urethanes can be applied in temperatures as low as 35 degrees Fahrenheit, depending on the formulation, which extends coating application windows and painting seasons to minimize scheduling delays.

Polyaspartic urethane systems enhance productivity for numerous field applications such as production tanks and piping.

Delivering Over a Decade of Proven Performance

From third-party accelerated testing validations to more than 10-year field application studies on bridges, railcars and other assets, DTM and two-coat polyaspartic urethane systems demonstrate long-term durability that equals or exceeds the performance of traditional two- and three-coat polyurethane systems, respectively.

For example, a performance study on more than 250 standard rail hopper cars coated with a DTM polyaspartic urethane showed less than 1 percent rusting after being in service for 11 years. Even better, the cars likely won’t need to be recoated for the rest of their service lives. The applicator also realized over 30% labor savings—from 15.5 hours to 10.5 hours per car to complete surface prep through final stenciling—by using the DTM polyaspartic urethane compared to a two-coat polyester urethane.

Following 11 years in service, this rail car coated with a DTM polyaspartic urethane system showed less than 1 percent rust.

A long-term study of a bridge coating project in Virginia showed that a two-coat polyaspartic urethane system provided the same level of corrosion protection as a three-coat system on 15 bridges exposed to similar conditions after 10 years. A similar study on a Connecticut bridge showed less than 2 percent rust on steel beams coated with a two-coat polyaspartic urethane following 13 years of service. Both studies demonstrate the system’s long-term performance potential.

A two-coat polyaspartic urethane used on this Virginia bridge with a concrete deck was rated very good after 10 years in service.

Enhancing Outcomes for Numerous Applications

Ideal for use in maintenance or new construction projects, polyaspartic urethane systems can be used for bridge and highway projects, production and storage tanks, steel fabrication, other structural steel, rail cars, pipes, and commercial and architectural applications. With over a decade of proven performance, polyaspartic urethanes demonstrate the long-term performance, durability and aesthetics of conventional two- and three-coat systems in just one or two coats. The systems’ fast-curing, reduced-coat performance, high film build and long-term performance capabilities are making polyaspartic urethanes the systems of choice for anyone focused on faster throughput shop applications, faster turnaround field projects, and reduced costs.


Bruce Toews, Sherwin-Williams Protective & Marine Coatings

Bruce Toews serves as Global Market Director, Process Industries, for Sherwin-Williams Protective & Marine Coatings. He’s been with the company for 30 years and previously was Global Market Director for Oil & Gas and Vice President of Global Accounts. He’s a NACE CIP Level III instructor and a committed NACE and SSPC member.




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