Sherwin-Williams Protective & Marine Coatings (Cleveland, Ohio, USA) has developed a new version of its CarClad Macropoxy HS, a high-solids epoxy designed as a protective coating for railcar exteriors.
The new product—CarClad Macropoxy HS 4200 extended weathering epoxy—delivers the same long-term corrosion protection and abrasion resistance as its predecessor, and now solves a long-standing aesthetic challenge related to epoxies and UV (ultraviolet) exposure, according to the manufacturer.
While maintaining effective corrosion protection, exterior epoxy coatings tend to change color as they chalk after a year or two in sunlight, the manufacturer explains. For example, black coatings turn to gray. By contrast, the new epoxy solves this by chalking black, instead of gray, so that black railcars will retain their color and aesthetics much better over their full maintenance interval.
This improvement to high-solids epoxy coatings addresses a growing trend in the industry, according to the manufacturer. While the primary role of the exterior epoxy coating on tanker and hopper cars remains protection from the elements, corrosion, and abrasions, railcar owners and leasing companies have begun to hear from their operating customers that they would like tanker and hopper cars to stay black and continue to look attractive over many years.
Previously, railcars that had chalked gray after only a couple of years could require a new coating if they were being leased to a new customer. However, the new coating will reduce costs for railcar owners and lessors because they will no longer have to recoat tanker railcars before the coating’s corrosion-resistant properties have reached the end of their life, according to the manufacturer.
While the main objective of the new product was to improve appearance after UV exposure, the epoxy also possesses other virtues that railcar customers value, including flexibility of application. Coating railcars in a time-efficient manner is no easy task due to complex geometries and time demands, according to the manufacturer, who notes that the coating can be applied at proper film builds (4-6 mils [101.6 to 152.4 microns] of dry film thickness) while allowing the painter to hang additional wet mils in areas requiring overlapping coats.
The product is also solvent-based, which means there is more latitude in terms of application conditions, such as temperature, than with waterborne epoxies. It can be applied with the same equipment and techniques as the predecessor product, accommodating both single-leg and plural-component sprayers, according to the company.
Source: Sherwin-Williams Protective & Marine Coatings, protective.sherwin-williams.com.