News | Oct 10, 2018

Repairing, salvaging bulletproof glass easier with new coating

Navy scientists attain better protection and visibility with a plastic coating that allows scratches to be ironed out

U.S. Marines patrol in a Humvee during a field exercise at Marine Corps Base Camp Pendleton, Aug. 14, 2018.

Dalton Swanbeck/USMC

Armored vehicles like the Humvee, known as gun trucks, were the primary ground maneuver unit during much of Operation Iraqi Freedom.

Small arms fire and improvised explosive devices would crack and scratch a gun truck’s bulletproof windows. The soldiers that maintained the gun trucks would often visit scrap yards looking for replacement windows and windshields.

But while investigating new types of armor, two scientists at the Naval Research Laboratory found something that could provide another solution that doesn’t rely on finding a replacement.

Drs. Charles Michael Roland and Raymond Gamache discovered that an atactic polypropylene coating enhances ballistic protection of bulletproof glass and can be salvaged by ironing out the scratches.

“An advantage of this transparent polymeric coating is its reversible solidification (as opposed to solidification via a practically irreversible chemical change in other polymers),” according to the patent. “Thus, abrasions and scratches may be removed by heating, optionally while contacting the surface of the polymer with a smooth surface. It was found that a temperature of about 100° Celsius was sufficient to repair atactic polypropylene. Such repairs could easily be made in the field.”

The U.S. Patent and Trademark Office reissued the Navy patent in June, just a month before the Marine Corps Systems Command said it hoped to save more than $100 million by removing armored gunner turrets (containing bulletproof glass) from older Humvees for use on the new Joint Light Tactical Vehicles being fielded in 2019.

News Article Image of Repairing, salvaging bulletproof glass easier with new coating

Logisticians and equipment specialists from Marine Corps Systems Command and Program Executive Officer Land Systems install a Marine Corps Transparent Armor Gun Shield on a Joint Light Tactical Vehicle. The installation is part of a cost-savings plan to harvest Gunner’s Protection Kits and other equipment from older Humvees and increase survivability.

Kristen Murphy/USMC

If adopted by suppliers of bulletproof glass, the technology would save many more windows and windshields, and more importantly, protect our warfighters and allow them to see properly out of their vehicles, said Brian Metzger, senior technology manager at TechLink.

Metzger is helping the Naval Research Laboratory find commercial partners for new armor technologies. He said that research from defense laboratories is available to the private sector for the development of new products and services, including non-military applications.

“The costs of innovation drop significantly when it’s been funded by the Department of Defense,” Metzger said.

Businesses interested in adding DoD technology to their products will most likely need to sign a patent license agreement to receive the technical data package, Metzger said.

Their first step is to contact TechLink, the DoD’s partnership intermediary for technology transfer, which assists companies, at no charge, through the federal technology transfer process, including the development of a commercialization plan and patent license application.

“We’re continuously helping companies acquire technologies from the Army, Navy, and Air Force,” Metzger said. “We love putting agreements together. It’s good for the defense innovation base and the national economy.”

For more information contact Brian Metzger at or 406-994-7782.