Humans throughout recorded history have used various types of materials as body armor to protect themselves from injury in combat and other dangerous situations. The first protective clothing and shields were made from animal skins. As civilizations became more advanced, wooden shields and then metal shields came into use. Eventually, metal was also used as body armor, what we now refer to as the suit of armor associated with the knights of the Middle Ages. However, with the invention of firearms around 1500, metal body armor became ineffective. Then only real protection available against firearms were stone walls or natural barriers such as rocks, trees, and ditches.
Soft Body Armor
One of the first recorded instances of the use of soft body armor was by the medieval Japanese, who used armor manufactured from silk. It was not until the late 19th century that the first use of soft body armor in the United States was recorded. At that time, the military explored the possibility of using soft body armor manufactured from silk. The project even attracted congressional attention after the assassination of President William McKinley in 1901. While the garments were shown to be effective against low-velocity bullets, those traveling at 400 feet per second or less, they did not offer protection against the new generation of handgun ammunition being introduced at that time. Ammunition that traveled at velocities of more than 600 feet per second. This, along with the prohibitive cost of silk made the concept unacceptable. Silk armor of this type was said to have been worn by Archduke Francis Ferdinand of Austria when he was killed by a shot to the head, thereby precipitating World War I.
Early Bullet Proof Vests Patents
The U.S. Patent and Trademark Office lists records dating back to 1919 for various designs of bullet proof vests and body armor type garments. One of the first documented instances where such a garment was demonstrated for use by law enforcement officers was detailed in the April 2, 1931 edition of the Washington, D.C., Evening Star, where a bullet proof vest was demonstrated to members of the Metropolitan Police Department.
The next generation of anti-ballistic bullet proof vest was the World War II “flak jacket” made from ballistic nylon. The flak jacket provided protection primarily from ammunitions fragments and was ineffective against most pistol and rifle threats. Flak jackets were also very cumbersome and bulky.
Lightweight Body Armor
It would not be until the late 1960s that new fibers were discovered that made today’s modern generation of cancelable body armor possible. The National Institute of Justice or NIJ initiated a research program to investigate development of a lightweight body armor that on-duty policemen could wear full time. The investigation readily identified new materials that could be woven into a lightweight fabric with excellent ballistic resistant properties. Performance standards were set that defined ballistic resistant requirements for police body armor.
In the 1970s, one of its most significant achievements in the development of body armor was the invention of DuPont’s Kevlar ballistic fabric. Ironically, the fabric was originally intended to replace steel belting in vehicle tires.
The development of kevlar body armor by NIJ was a four-phase effort that took place over several years. The first phase involved testing kevlar fabric to determine whether it could stop a lead bullet. The second phase involved determining the number of layers of material necessary to prevent penetration by bullets of varying speeds and calibers and developing a prototype vest that would protect officers against the most common threats: the 38 Special and the 22 Long Rifle bullets.
Researching Kevlar Bullet Proof Vests
By 1973, researchers at the Army’s Edgewood Arsenal responsible for the bullet proof vest design had developed a garment made of seven layers of Kevlar fabric for use in field trials. It was determined that the penetration resistance of Kevlar was degraded when wet. The bullet resistant properties of the fabric also diminished upon exposure to ultraviolet light, including sunlight. Dry-cleaning agents and bleach also had a negative effect on the antiballistic properties of the fabric, as did repeated washing. To protect against these problems, the vest was designed with waterproofing, as well as with fabric coverings to prevent exposure to sunlight and other degrading agents.
Medical Testing of Body Armor
The third phase of the initiative involved extensive medical testing to determine the performance level of body armor that would be necessary to save police officers’ lives. It was clear to researchers that even when a bullet was stopped by the flexible fabric, the impact and resulting trauma from the bullet would leave a severe bruise at a minimum and, at worst, could kill by damaging critical organs. Subsequently, army scientists designed tests to determine the effects of blunt trauma, which is injuries suffered from forces created by the bullet impacting the armor. A byproduct of the research on blunt trauma was the improvement of tests that measure blood gases, which indicate the extent of injuries to the lungs.
The final phase involved monitoring the armor’s wearability and effectiveness. An initial test in three cities determined that the vest was wearable, it did not cause undue stress or pressure on the torso, and it did not prevent the normal body movement necessary for police work. In 1975, an extensive field test of the new Kevlar body armor was conducted, with 15 urban police departments cooperating. Each department served a population larger than 250,000, and each had experienced officer assault rates higher than the national average. The tests involved 5,000 garments, including 800 purchased from commercial sources. Among the factors evaluated were comfort when worn for a full working day, its adaptability in extremes of temperature, and its durability through long periods of use.
The demonstration project armor issued by NIJ was designed to ensure a 95 percent probability of survival after being hit with a .38 caliber bullet at a velocity of 800 ft/s. Furthermore, the probability of requiring surgery if hit by a projectile was to be 10 percent or less.
A final report released in 1976 concluded that the new ballistic material was effective in providing a bullet resistant garment that was light and wearable for full-time use. Private industry was quick to recognize the potential market for the new generation of body armor, and body armor became commercially available in quantity even before the NIJ demonstration program.