In a number of high-tech applications, engineers need to specify a hard electrochemically deposited gold coating that combines the theoretical reflectivity and emissivity of gold, with a surface that can actually be physically cleaned. This is not at all easy to achieve! However, over the last two decades, a small firm in Brooklyn, New York, has become the world’s leading supplier of such a material.

The firm, Epner Technology, is a family owned business that opened its doors in 1910. Starting with decorative electroplating, the firm has grown into the world's leading supplier of an electroplated, infrared reflective, optical coating for the aerospace, medical, computer and defence industries. The proprietary Laser GoldTM material can be applied to imaging optics with no distortion of the optical figure and the remarkably low emissivity (.02) makes it the ideal choice for a huge number of advanced applications. A scanning electron microscope examination of the surface reveals a nano-crystalline deposit of pure gold.

Why use gold for these applications? Whilst not widely known, gold is the most durable and efficient reflector of infrared energy. In visible light gold might only reflect about 40%, but in the infrared spectrum, a freshly vapour deposited or sputtered gold, although extremely fragile, can achieve more than 99%! Pure electroplated gold, can almost duplicate the vapour deposited gold's reflectivity, but it is too is delicate. If alloyed with cobalt, for example, it becomes rugged enough, but the coating degrades with sustained heat. The impetus to develop a suitable high performance, durable coating came from the company Xerox and their urgent need to source such a material for one of their machines. With the "carrot" of more business that this small company had ever seen, Epner's chemical engineers embarked on an R & D effort to develop a gold plating process that could withstand the abrasion of the passing paper, the occasional cleaning effort and yet meet Xerox's relatively low reflectivity specification of 91%.

The research effort was successful and Epner started to increase production but the euphoria was short lived. Tests at Xerox showed that reflector performance was inconsistent. To the distress of Epner’s management and production team, hundreds of reflectors were rejected as "out of spec" for reflectivity; something that could not be judged with the human eye. It quickly became apparent that without the same instrument that Xerox used to measure reflectivity, Epner could never be sure the product they were shipping met specification. Xerox provided Epner with the identical state-of-art infrared spectrophotometer. This single tool sparked a renewed R & D effort that over the ensuing years continuously improved both the reflectivity and hardness. For more than twenty years since, Epner Technology has been the sole supplier to the National Bureau of Standards, today known as NIST, of the gold reflectance reference standard. You would calibrate your spectrophotometer with a mirror that was manufactured in Brooklyn.

Despite the trade name, producing the Laser Gold material does not actually involve use of a laser. The name was adopted when the first company, other than Xerox, to profit from this unique coating, was an Nd-Yag laser manufacturer. Epner soon became the "go to" source in the Yag laser industry for this high efficiency coating, Thus the name, Laser Gold, which is today, a trademarked brand known world wide.

With Epner’s commitment to rigorous process control, the firm’s customer list includes highly visible – and demanding – companies in the aerospace, electronics, optical and computer industries. During the past twenty years, Epner Technology’s most impressive projects have involved work for NASA, both directly and indirectly through its suppliers such as Ball Aerospace, Raytheon, and Lockheed among others. An example, is the Mars Orbiter Laser Altimeter Mirror (MOLA), designed to map the topography of the Red Planet, which used Laser Gold coatings.

Epner Technology has also participated in one of the longest-running NASA programs; the Geostationary Operational Environmental Satellite (GOES). This satellite provides the real time weather images that we see daily on the news and every one over the past twenty-five years, has had the performance enhanced with Laser Gold's consistently low emissivity, which helps maintain the thermal stability of key instruments.

There are some interesting commercial applications for Laser Gold coating and other Epner Technology products that are spin-offs of the space and weapons work. Epner is currently working with NASCAR and Formula-1 designers to develop a flexible heat barrier in racecars, providing a safer and more comfortable driver’s compartment and in other cases, permit fuel and brake fluid to run cooler and/or protect the carbon fibre composite material from over curing from exhaust pipe heat.

Another current project will allow firemen in smoke-obscured buildings to see through the smoke with infrared sensors which can read Laser Gold fabric reflectors, coded to identify individual fire-fighters, through the smoke. Flexible gold mesh or foil can be laminated to protective clothing to repel heat, increasing a worker’s safety, comfort, and endurance on the job.

“From gas detection cells to micro light-pipes that get threaded into the heart, it’s been an exciting business. We've learned, we've grown, and we've participated in some of the most "envelope pushing" projects in the world. Almost every day a new challenge comes through the door, (more likely the Internet) and I get to have lunch with some of the top scientists and engineers in the U.S. and Europe.” says President of the company, David Epner. "At 74, retirement is just not part of my lexicon."

David Epner
Epner Technologies
For more information visit www.epner.com
LaserGold is a registered trademark of Epner Technology, Inc.
Read more in Aviation Week and Space Technology www.epner.net/news/aviationWeek