Posts Tagged ‘kevlar’

Well, you asked, I listened. With all the mail volume I get, this single request was the most common. Thanks everyone for their patience, I have been extremely busy of late with travel, testing, evals, and even a tiny little bit of personal life. 🙂

When it became clear that Zylon was a huge liability and safety hazard in soft armor, lots of people wanted to know if their vests contained it. With the more recent realizations that first and second generation aramid laminates such as GoldFlex and GoldShield, and UHMWPE laminates such as Dyneema and Spectra have notable drawbacks and Achilles Heels, identifying these has also become important.

And so, without further ado, here is how you determine what kind of stuff your armor contains.

1. The first step is to field strip your armor. Most concealable vests today are multi-component, consisting of an outer shell or carrier, and an inner ballistic package. These are generally bottom-load, with the closure consisting of strips of hook and loop along the bottom seam. There are some manufacturers that use a top-load, and some that use a “mid-load” with a seam across the middle part of the vest. Regardless, determine how to get your ballistic panels out of the carrier, and we can get to the next part.

2. Look at your ballistic package. About 80-90% of modern vests will have the actual material encapsulated in some sort of secondary shell, usually consisting of GoreTex, or thin Nylon ripstop that has heat sealed edges. If this is the case, skip to part 4, since you will be using texture and feel to determine what you have.

3. If you have one of the 10-20% of vests that does not have the ballistic material encapsulated in a secondary shell, you will be able to use visual means of determining the composition. I have included closeups of the four materials found in vests to aid in identification:

100% Woven Kevlar- The Gold Standard for body armor

100% Woven Kevlar- The Gold Standard for body armor

A. Woven Kevlar- This is the material you want to see. It appears as a bright yellow fiber, with discernable warp and weft. Ideally, your armor consists of nothing but this.

GoldFlex- Not the most optimal material, but could be worse...

GoldFlex- Not the most optimal material, but could be worse…

B. Aramid Laminates- This material will have the same bright yellow appearance as woven Kevlar, but will not have any warp/weft. It will appear glossy, shiny, or slippery, due to the plastic film that covers it. Not optimal, but better than the next two.

UHMWPE- Milk Jugs with delusions of grandeur.

UHMWPE- Milk Jugs with delusions of grandeur.

C. UHMWPE Laminates- Either Spectra or Dyneema, this material will have a pearlescent, white, shiny/waxy appearance. Less desirable than aramids.

Zylon- "Danger, Will Robinson, danger!"

Zylon- “Danger, Will Robinson, danger!”

D. Zylon- DANGEROUS TO WEAR, this material is a liability and should immediately be discarded. Zylon, in its woven iterations, has a bright orange or bronze tint. In its laminate form, it will exhibit the same coloration, minus the weave pattern. Any armor containing Zylon should no longer be worn, and if possible discarded and replaced.

4. If your armor package is wrapped up in a secondary shell material, you have two options: see if there are any rips, tears, or holes in the material of the shell (to allow visual inspection), or rely on tactile sensitivity. The former is only possible if the armor is older, and there is existing wear or damage to the inner shell. Not an ideal circumstance. The latter will not allow you to determine the composition of the armor with very much accuracy, but is better than nothing.

Pull the shell material tight, and feel both the front and the back. If there is a detectable weave texture on both sides, you have a fairly good chance that the vest is made with 100% woven material. If older than 1990, it is MOST LIKELY woven Aramid, though there is a small chance it is Spectra Flex. If newer than 1998, there is a CHANCE it is made with woven Zylon. If you are worried this is the case, making a small slit in the shell material (if the inner shell is heat sealed) or using a seam ripper to pull about an inch and a half of the seam for visual inspection is advised. If handy with a needle and thread, this can be sewn up again.

If the material on one or both sides feels slick/slippery, then it indicates a laminate hybrid or 100% laminates respectively. Again, if it is of grave concern, a small inspection slit may be made in the inner shell. AGAIN, CUTTING A SLIT/RIPPING SEAMS SHOULD NOT BE DONE TO ARMOR THAT IS UNDER WARRANTY, AS THIS MAY VOID YOUR WARRANTY THROUGH THE MANUFACTURER.

Thus concludes the turorial. It will also be helpful to consult the label, and do a little research beforehand to see what materials you vest potentially contains. Hopefully this was helpful in determining your vest’s innards!

And, faithful readers, it is the first of several tutorials I intend to offer. Until next time!

And so it was that a great need was upon the land. With projectiles achieving higher velocities, and greater penetration, Nylon just was not cutting the mustard. Even though it excelled silk for use in soft armor, it still lacked the requisite tensile strength to stop modern copper jacketed handgun rounds in anything approaching wearable ADs.

In 1965, a Dupont chemist named Stephanie Kwolek stumbled upon a new material while searching for alternatives to steel in tire reinforcements. This new material had a tensile strength 5 times that of steel on an equal weight basis. The structure resembled natural silk, but what made Kevlar outstanding was the propensity for the fibers to form cross-linked hydrogen bonds at 90 degrees to the polymer chain. This gave the new fiber exceptional tenacity, making it ideally suited for use in ballistic armor.

This, combined with excellent heat and flame resistance (Aramid fibers do not burn, they char at around 700 F), lead to a resurgence in concealable personal body armor. Richard Davies, founder of Second Chance, immediately saw the potential of this fiber, and the modern “bulletproof vest” was born.

Kevlar is the trade name for aramid fiber developed by Dupont, but there are several different brands of aramid fiber, including Teijin’s Twaron. Though originally discovered by Dupont, Teijin, a Netherlands based company, perfected and patented an aramid fiber processing method that Dupont later licensed to use themselves. Whether we are talking about Kevlar aramid or Twaron aramid, the properties are very similar.

To this day, aramid is widely used in armor applications. During the 70’s and 80’s, the only form used was woven fabric, cut and layered up to 35 plies deep. In the 90’s, new iterations of bullet resistant composites were brought to market, including laminates.

Laminates were introduced in search of the ever moving goal post of thinner and lighter armor. Of course, as has been the case throughout history, heavy and cumbersome armor is not fun to wear. To get folks to wear their armor, thin and light make sense. However, as will be seen, laminates were not necessarily better, and could even be seen as a step backwards (at least the first and second generation iterations).

Laminates such as Goldflex and Gold Shield utilize polypropylene films (chemically similar to food preservative film) to sandwich unidirectional aramid fibers in alternating 0 degree and 90 degree layers. Admittedly, this results in a very good material for stopping bullets, including hits near the edge of a panel, and at acute angles to the panel.

Unfortunately, several drawbacks rear their ugly heads with aramid laminates. First off, they have the breatheability of plastic wrap. Which is zero, since similar materials are used as vapor barriers. Secondly, the plastic film has a nasty tendency to melt when the panel is subjected to the hot muzzle blast of contact shots (an event all-to common in the course of law enforcement). In contrast, woven aramid is extremely effective at resisting contact shots. Finally, armor made with first and second generation laminates experience accelerated wear, since the adhesion of the film is degraded by repeated exposure to flexing, heat, cold and moisture.

While an armor built with woven aramid could reasonably be expected to survive (and remain fully effective!) for over 25 years (and I have personally verified that they HAVE), a laminate constructed armor is usually toast after only two years of normal wear. The edges curl, the layers peel apart, and the ballistic effectiveness drops to unsafe levels. In much the same way that a chain is only as strong as its weakest link, first and second generation laminates are hobbled by their use of, essentially, plastic wrap in their construction.

Next episode, we will look at another laminate, one that has great numbers, but hidden dangers…