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Supplement, November 2000

Weathering the Storm

Choosing Hardware to Withstand Nature’s Havoc

by John Imbriale

My neighbor and I were talking about the weather the other day. “This is the third wettest summer we’ve had in recorded history,” she said. “No doubt we’ve seen our share of rain, but I wonder what this winter will bring,” I answered. We have reason to be suspicious. After all, in an area that is subjected to hot, humid, sweltering summer days and balmy nights, our weather was cool and wet. And not just wet … waterlogged. I have lived in Southeastern Virginia for almost 25 years and it was the most rain I have ever seen—triple what we normally experience.

As I thought about it more, I recollected conversations with customers and colleagues all over the United States and Canada. So many people are talking about the weather. Not just idle, small talk, but rather deep, intellectual conversations that are more common to Sunday afternoon chess games and after-dinner brandy. Regardless of the region, the consensus seems to be that our weather has been strange during the last few years.

Now, I am not a meteorologist, but I do know what really matters when it comes to weather—perception. These perceptions are driving the window and door hardware market in positive directions.

This year more than last, and last year more than the year before, we get increasing requests for hardware that gives people confidence that their windows and doors will operate effortlessly despite extreme weather conditions. Our business is European window and door hardware. Most of our products, by design, are made to help fenestration resist the effects of extreme weather—such as multi-point locking systems that prevent water and air infiltration. We manufacture hardware designed to keep even the most delicately-crafted, oversized windows and doors from warping.

Many types of European hardware have undergone subtle design changes over the last several years. These changes are spawned by the ideas and needs of the market. The market is composed of people who have strong opinions about the effects of weather, and their ideas and needs are focusing on materials capable of withstanding the most extreme conditions. In short, people want hardware that can survive a high salt air environment and excessive moisture exposure to provide a long, maintenance-free service life. Hardware manufacturers are quickly responding to these demands.

Zinc Dichromating

For many years, the industry standard has been to zinc dichromate metal alloys to improve the rust and corrosion resistance. Zinc dichromating? You know … that gold, iridescent finish vaguely reminiscent of those famous sunglass lenses. Zinc dichromating is a dipping process that coats base metals with a protective skin. Under most conditions, zinc dichromated materials work extremely well. However, certain applications subject hardware to an exorbitant amount of salt and moisture. Coastal applications, for example, present the greatest challenges due to the constant presence of salt and moisture. Under these conditions, zinc dichromated materials will often develop a white, salty
corrosion.

The hardware industry recognizes the limitation of zinc dichromating and is using stainless steels and coated metals to improve rust and corrosion resistance performance. True, many companies have long promoted lifetime brass finishes for decorative hardware. Stainless steel and coated metals are common in this genre, as well. But it is the operational hardware market that has been most recently influenced by these materials.

Stainless Steel

It makes sense that stainless steel would be the material of choice for coastal applications. After all, stainless steel is permanently stainless—eternally free of rust and corrosion. This is true in some instances and completely false in others. The critical factor that determines if stainless steel will perform satisfactorily is grade selection. Market intelligence feels that stainless steel is the best material because it does not rust or corrode. But market oversights do not realize that certain types of stainless steel can and do rust.

Stainless steel grades comprised of 11.5 percent or more chromium (such as 300 series) are essential for hardware applications. The chromium uses atmospheric oxygen to form an invisible, highly protective surface film that prohibits oxidation, resists dyes and organic chemicals. The 300 series is the most versatile and widely applied grade of stainless steel. In fact, 304 stainless steel accounts for more than 50 percent of the stainless steel currently produced worldwide.1

While stainless steel is an excellent material for window and door hardware, it is not without shortcomings. The most obvious limitation is cost. The 304 stainless steel, from which hardware components are commonly manufactured, is approximately four times more expensive than mild steel. Added to the increased raw material costs are increased manufacturing costs, since stainless steel is more difficult to work and machine.

Despite being inherently harder than most architectural metals, 300 series stainless steel cannot be hardened thermally. This makes 304 stainless steel a poor choice for mechanical components (especially gearing) with a shorter service life than hardened mild steels.

Dissimilar grades of stainless steel cannot be in contact with each other. When this occurs, a galvanic reaction is encountered where the weaker grade succumbs to the superior grade. To avoid this conflict, one must ensure that all stainless steel components being used are grade homogeneous. This may be difficult in situations where several manufacturers supply components for a single application.

 Coated Metals

Coated metals are emerging in the hardware market as an alternative to stainless steel. The process, performed to steel or zinc alloy components after manufacturing, is less expensive than the cost of stainless steel. Therefore, coated materials represent an affordable method of improving rust and corrosion resistance.

One significant advantage to coated materials (compared with stainless steels) is that components can be machined from workable, mild, steel grades. Then, when necessary, thermally hardened to increase the service life before the finish coatings are applied. In the end, the component is harder than stainless steel with similar (or better) rust and corrosion resistance.

Hardware designed to meet industry standards and market expectations must be subjected to rigorous testing. Salt spray testing, conducted in accordance with ASTM B-117 procedures, is intended to simulate the salt and moisture conditions common to coastal areas. Coated components have been found to outperform zinc dichromated components by three times or more.

Excellent for use in harsh environments, coated metals are not really a new idea with regards to hardware. Door hardware has been available in coated finishes for at least the last five years. But as the market trends point to greater requirements for hardware to withstand extreme weather conditions, there have been developments to enhance coated finishes. Additionally, the applications for which coated finishes are used have spread to a wider array of hardware types.

While coated hardware components are capable of resisting rust and corrosion, there are a few points worth remembering. Coated materials are only as good as the integrity of the coating itself. In other words, if the coating is comprised (scratched, chipped or otherwise affected), the sub-material will be exposed to whatever conditions are present. As a specific protection against this possibility, hardware components may be zinc dichromated before coatings are applied. This will provide an additional defense against the effects of weather. However, in extreme weather conditions, the material may eventually show signs of rust and corrosion.

 Material Improvement

Since customers are interested in materials that will withstand severe weather conditions, the window and door hardware industry is improving on the materials available to provide better protection to customers. From a material perspective, there are three keys to ensuring that the hardware being considered will survive the intended application:
• Realize your environment and the strains it may place on window and door hardware components;
• Understand the materials available and how they will (or will not) react under certain conditions;
• Make an educated material selection that best satisfies requirements.

The weather may not be predictable and perceptions about the weather may change. But hardware manufacturers will continue improving hardware with materials that provide complete rust and corrosion protection.  

John Imbriale serves as customer service supervisor for G-U Hardware based in Newport News, Va.

1 Australian Stainless Steel Development Association (ASSDA)

DWM

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