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Kevlar vs Spectra Shield: The ballistic generation gap

Without a doubt today’s new state-of-the-art weapons, high velocity rounds and metal jacketed bullets are now exceeding design limits considered adequate for soft body armour. It’s this high performance firepower that makes police work more dangerous than ever - making increased armour performance vital to officer survival. In the days of six-shot revolvers and low velocity round-nosed lead ammunition, layers of woven nylon fabric made an effective ballistic barrier. But as the velocities increased and jacketed bullets entered the scene, a new generation of material was needed to stop these faster, more deadly rounds. The second generation fabric was a material called Kevlar

The Second Generation - Kevlar

Made with chemical and fibre technology from the late 60’s, aramid fabric allowed vests to be stronger, less bulky and lighter than nylon. And, Kevlar is still the most common ballistic fibre used in the production of soft body armour.

Into the 90’s, The Third Generation - Spectra Shield

Now, an amazing new third generation material called Spectra Shield is being used by vest manufacturers to make soft body armour designed for the 90’s and beyond. Ballistic panels made with Spectra Shield are proven performers in multiple-hit, angle shot, and high velocity situations - meeting today’s threat head-on. Spectra Shield is made from Spectra, an incredibly strong fibre developed by the scientists at AlliedSignal. They took the polyethylene material widely used in products such as durable “carry all” grocery bags and altered its molecular structure. The result- SPECTRA, an incredible light, ultrathin fibre, 10 times stronger than steel. Spectra Shield material is constructed from thousands of strands of unidirectional fibre layered in 0 and 90 degree angles. These layers are held in place by flexible resins, sandwiched between two sheets of a polyethylene film similar to Saran Wrap

Comparing the two materials

1. Kevlar Aramid Fibre

The plain weave structure of aramid material is much like the weave found in many domestic materials. Angle shots have been shown to sometimes “slip” the weave and push aside ballistic yarn strands. National Institute of Justice statistics show that certain styles of Kevlar fabric can lose up to 20 per cent of their ballistic efficiency when struck at an angle.

The Traditional Approach

The traditional approach to stopping a bullet was to “catch” it with several layers of woven material made from the strongest fibre available at the time. As a bullet would pass through a layer of the woven fabric, its tip would engage thousands of individual fibres. These fibres would stretch and break as energy was transferred outward through the fibres into the weave. As it passed through each progressive layer, the bullet would continue to lose energy as it was deformed or flattened, eventually bringing it to a stop.

A New Angle

The old approach worked great with softer, lower velocity bullets, but the high velocity steel jacketed rounds officers face today push woven fibre materials to their limit.

And in angle shot situations these rounds may actually “slip through” a weave by separating the individual cross yarns. The only solution is to add more layers of material, or to sew the existing layers of material together, and that often means extra weight and discomfort.

In contrast, the unique construction of Spectra Shield material does a much better job of engaging high velocity jacketed bullets by dispersing energy faster, and across a wider surface than possible with woven fabric - especially in angle shot situations.

2. Spectra Shield

Spectra Shield material is constructed to immediately flatten the end of a bullet, and then to stop it dead in its tracks - even at the toughest of angles. The layers of material are thinner and lighter than traditional woven material making for a lighter, more compact and most importantly, more effective vest.

The 0-90 degree edge Spectra Shield is not a woven material, but instead a thin, flexible ballistic composite made from two layers of unidirectional fibres held in place by flexible resins. These Spectra fibres are arranged so they cross each other at 0 and 90 degree angles. Then, both fibre and resin layers are sealed between two thin sheets of polyethylene film similar to Saran Wrap. This ultra high-performance ballistic material is thin, lightweight and unaffected by moisture or chemicals, yet at the same time it’s also very flexible.

Not cut from the same old cloth

Spectra Shield material’s patented structure virtually eliminates any gaps between fibres and holds them firmly in place during a ballistic event. Unlike woven ballistic fabrics, Spectra Shield material’s fixed fibre orientation keeps high velocity metal jacketed rounds from pushing the fibres apart and transfers energy away from the point of impact in all directions.

The energy dispersion pattern of Spectra Shield covers a wider, more rounded area, flattening the bullet by sending energy across the surface at incredible speed, bringing the bullet to a quick stop.

Spectra Shield composite, and Spectra fibre based fabrics are currently being used in countless vest and armament applications. Independent tests, and tests conducted by the National Institute of Justice are showing that vests made with Spectra Shield demonstrate a consistent performance advantage in higher velocity, multi-hit, angled shot and wet test scenarios.

Pound for pound Spectra Shield has the performance advantage at higher velocities. At 1.00 pound per square foot, the top of the scale, Spectra Shield has 9mm stopping power of just under 1650 feet per second compared to Kevlar 129 at 1510 and Kevlar 29 at 1450 feet per second.

It’s this increased performance that Spectra Shield composite vests offers that can be the difference between life and death.