Materials used in Bullet Resistant Jackets (BRVs) or Body Armour
Published: 31st May 2021
Generally speaking, the lighter it is, the more it costs. This is the second in a series of articles on bullet resistant vests by Deon du Plessis, MD of Bullet Proofing Technology (Pty) Ltd, in which he outlines the soft and hard materials which go into BRVs. His business manufactures a wide range of body armour plates and vehicle armour, and supplies a number of other bullet resistant vest manufacturers.
1. Outer material.
The outer cover of body armour is the part that is seen and used as a “carrier” garment with pockets for paraphernalia and to carry the armour panels and/or plates. It doesn't cost much, and can be any colour, have pockets, “Molle” straps and even printing. The choice of the outer material is, however, quite important, as it serves as the base to carry the armour panels, plates and equipment of the wearer, and also identifies him. Durability is very important as this garment takes on a very punishing role. Brushed nylon, such as “Cordura”, and heavy-duty rip-stop materials are commonly used, but it is very important to consider all options, as the choice of the outer material does not have a very large influence on the cost of the BRV but could make it last much longer.
2. Soft armour
a. Aramid, which is commonly referred to as “Kevlar”.
Poly-paraphenylene terephthalamide is the chemical name of the original Kevlar K-29 developed by Stephanie Kwolek at DuPont in 1965. The original application of this fibre was as lighter-weight replacement for steel wires in racing tyres. It is spun in thin fibres and then woven into ropes, cables or fabric and is also used as an ingredient in composite materials. It has many applications, and the main market is still tyres for cars, bikes and aircraft, but a very large portion is used in bulletproof vests. It has an extremely high tensile strength to weight ratio, typically 5 x higher than steel, and is currently made by many different companies in the world, of which the main ones are: -
- a.i. “Kevlar”, made by DuPont
- a.ii. “Twaron”, made by Teijin
- a.iii. “Heracron”, made by Kolon
Aramid is the main material currently used in body armour in South Africa. The yarn is imported from Europe or Korea and woven into material locally. There are many different types of yarn woven into different weave styles and densities depending on the application. The most common types used in Body Armour in South Africa are 930 and 1100 Dtex fibres woven into material ranging from 190g/m² to 280g/m². Dtex is the weight in grams of 1 x yard length of the yarn. The 1100 Dtex yarns have been used since 1988 till now, while the 930 Dtex yarns are newer and have been used since 2004 till now. There are now even 800 Dtex and 530 Dtex yarns available, with the generalization that lower Dtex fibres can be used for lighter-weight and more flexible body armour, but their material and weaving costs are higher. So, to generalise, lower Dtex yarns provide lighter and more comfortable body armour, but at higher prices.
Because of the price disadvantage, 99% of all Aramid-containing body armour manufactured, sold and used in South Africa uses 930 or even higher Dtex yarns in 190g/m², 200g/m² or 280g/m² density weave material. By combining multiple layers together, soft armour packs are made up to install into soft armour jackets. The most common compositions for Level II protection (SANS 1658:2007), for protection against most common handgun threats, will consist of at least the following Aramid packs: -
- 25 x Layers of 190g/m² material (1100 Dtex) for an areal density of 4,75kg/m²
- 24 x Layers of 200g/m² material (930 Dtex) for an areal density of 4,8kg/m²
- 21 x Layers of 280g/m² material (1100 Dtex) for an areal density of 5,9kg/m²
Some manufacturers also use 300g/m² (Dtex) or 450g/m² (3360 Dtex) material in body armour, mostly to save cost, but these materials are not primarily intended for use in soft body armour and, because of its looser weave, might not stop bullets at angles, or yarns could move in the material sheets with time and need to be stitched or laminated together, which makes it less flexible.
One of the downsides of Aramid panels are that the Aramis material have a lower ballistic performance when wet, and Aramid soft armour are thus always encapsulated in water-tight “envelopes” or “packets”.
Currently Aramid is still the main material used in soft body armour in South Africa today because of its local availability, flexibility (comfort), proven track record, low weight, and reasonable price.
b. Ultra-High-Molecular-Weight Polyethylene (UHMWPE) is a type of polyethylene made up of long chains of polyethylene, which all align in the same direction in the length of the fibre. It is produced by gel-spinning a heated gel into fibres, which are then further extruded by drawing it through heated air before being cooled. The end fibres have a large degree of molecular orientation. The UHMWPE fibres have an extremely high tensile strength to weight ratio, typically 8 x higher than steel.
It is currently made by many different companies in the world, of which the main ones are: -
- b.i. “Dyneema”, made by DSM
- b.ii. “Spectra Shield”, made Honeywell
- b.iii. “Endumax”, made by Teijin
- b.iv. “Tensilon”, made by DuPont
- b.v. Quite a few Chinese manufacturers. In general (jokingly) we refer to these types as “Chineema”.
UHMWPE is the new kid on the block in Body Armour. Although the basic process was commercialized in the 1960s, it was only first introduced as woven fibre material layers into body armour in 1990. Since then, the main application of these fibres has moved into the field of Uni-Directional (UD) laminating, which is now the main application method in body armour. Multiple layers of UD laminates are stacked together to form the soft armour panels as used in body armour. There is currently no laminating facility to do this in South Africa, so all UHMWPE materials used in soft body armour are imported as sheet material on a roll, which is stacked and cut to shape to fit into the body armour garments.
The different manufacturers all have different names for their different types for different applications. “Dyneema”, “Endumax” and “Tensilon” are perhaps the best know and reliable materials in South Africa, with new improvements constantly launched, but the rest are continually catching up and currently seem to be 3 – 5 x years behind DSM with matching performance materials. All claim fantastic performance out of their newest materials, but these improvements mostly come at higher prices.
UHMWPE for soft body armour is fully imported as laminated material on a roll and is currently still more expensive than equivalent woven Aramid on a cost per jacket basis. UHMWPE does, however, have a weight advantage and is typically 20% lighter than Aramid soft armour of the generally used types, with a typically 20 - 50% price disadvantage. This is only indicative of what is currently available and typically used. Although UHMWPE has a weight advantage over Aramid, it is generally stiffer and less comfortable, as it consists of laminated layers, and not woven material. On the possible downside, UHMWPE can start burning when shot with tracer bullets, but this disadvantage is mostly exaggerated, as tracer handgun bullets are very uncommon.
Its footprint in South Africa seems to be getting larger, as more and more customers are opting for lower weight against higher pricing. This is helped further by the Chinese origin materials improving in performance to match 3 – 5 x years older Dyneema material, but at lower prices.
c. Ballistic Nylon was used in body armour since WW2, where it was used in “Flack Jackets” for airmen to protect them against fragments from anti-aircraft shells and bullet fragments. DuPont also led this development nearly 80 x years ago and it still being used today, but mostly as an “Outer Layer” fabric in protective wear such as motorcycle jackets. Some manufacturers have also been using it in combination with Aramid or UHMWPE soft armour to provide lower cost but slightly heavier body armour options to local users.
d. Hybrid. By combining all or some of the materials above, it is possible to use the advantages of some materials and off-setting its disadvantages by combining it with one or more of the other materials. As an example, by making a hybrid consisting of ±50% UHMWPE in combination with ±50% Aramid, the soft armour panels are more flexible than pure UHMWPE panels, but cheaper. In the same way they are lighter than pure Aramid panels, but a bit less flexible and more expensive.
e. Steel? The question mark behind the steel is there because steel is rigid and is not a “Soft” or “Flexible” armour type. Because of its low price, some users do use it in handgun protection level body armour though, and the comparison is required here. The general handgun protection level in South Africa is Level II. This will provide protection against normal 9mm bullets from most handguns as well as ,38 Special and .357 Magnum bullets from large handguns. By using the most advanced high-hardness armour steel, it is possible to use only 2mm thickness steel. This will weigh ±15,5kg/m² for the armour panels, which is 3 x times as heavy as the weight of Aramid panels and nearly 4 x times as heavy as UHMWPE panels of the same size. Alternatively seen, if the protection panels are the same weight, the steel panels will be 3 – 4 times smaller than the Aramid or UHMWPE panels. When this is considered together with the extreme stiffness of the steel-based panels, the price advantage needs be very much before most users will consider using thin steel-based armour panels in handgun level body armour.
It seems to be common practice for many bullet resistant material manufacturers to market their new developments through comparison to the existing offering of the competition, and sometimes even to 10 x year old materials from the competitor material. Nothing in this advanced technological field comes in giant steps and the old saying “If it seems too good to be true, it most probably is” is mostly applicable here. Improvements do happen continually, but users should not necessarily believe all the marketing material, especially that dealing with comparisons to the “Competition’s” material.
When considering which ballistic material to use or specify, each user of body armour will have its own priorities and needs to consider the following points before deciding on the best material for their specific requirement: -
- Local content
- Protection level
3. Hard armour panels or plates
A Bullet Resistant Vest would be fantastically comfortable if it could contain only flexible soft armour to provide protection against rifles as well! This is unfortunately still a fantasy many years away, and we still require hard armour of some or other rigid material to provide protection against most (if not all) common rifle threats. Protection against rifles is only obtained by inserting hard armour plates into bullet resistant vests or armour carriers, either in combination with soft armour panels which are already in the vest (in conjunction with plates), or on its own as stand-alone plates. These could consist of many different materials, the main ones discussed below: -
a. Armour Steel plates have been used as body armour for many centuries till the mid-1990s and have again recently staged a come-back through the development of High Hardness and Ultra-hard armour steel. In general, it is the heaviest of the hard armour materials, but has the lowest cost. The older medium- or high hardness types of 500HB hardness could be formed to fit the body better, but the newest Ultra-hard types of 630HB+ require very special processes to be bent to fit the body, which negates some of its lower-cost advantage. Armour Steel is no longer produced in South Africa and all of it is currently imported from Sweden, France, Germany, Australia or Belgium.
Steel-based hard armour plates do have some specific advantages and disadvantages in comparison to other hard armour plates. It does provide excellent multi-shot protection and is very durable, but on the downside it is quite heavy and has the problem that the bullets break up on hitting the steel, which then creates many small fragments flying in various directions off the front surface, most of it quite flat to the plate surface, impacting other body parts of the wearer, such as the neck, arms and abdomen. In order to lessen this danger, it is necessary to cover the front surface of the plate with an effective “Anti-Fragmentation” material. Many of the steel-based plates sold locally have inadequate anti-fragmentation covering, but, as a quantifying system is still not defined in the current version of the SANS 1658:2007 standard, it cannot be adequately measured and defined.
b. UHMWPE, when used as hard plates, is currently the lightest hard armour material available for protection against most common rifle threats. Well known under the trade names of “Dyneema” and “Spectra Shield”, some local manufacturers are also using it as the base of their “Ultra-light” and “Super-light” body armour plates. It consists of many layers of uni-directional UHMWPE material with special interlayer materials which are pressed together under very high pressures at a specific and accurately controlled temperature for quite a long time. The previous generation of UHMWPE plates requires a pressure of ±52 Bar, and this could provide protection against most locally found guns and bullets, except the AK-47 with the common Eastern Bloc produced and locally found bullet, which has a mild steel core. These older generation plates are still imported into the country at quite low prices, but users should be aware that they only provide protection against the AK-47 bullets with lead cores, which are not the bullets found in South Africa. To provide protection against the AK-47 bullets with mild steel cores, as what is commonly found in South Africa, newer types of UHMWPE materials need to be used produced by pressing at pressures in excess of 250Bar, which nearly doubles its price. Although most UHMWPE plates that are available are single-curved, the more comfortable multi-curved variety is also being manufactured in South Africa.
c. Ceramic tiles, as used as a full monolithic plate or smaller tiles, are often used as a component in body armour. Its extreme hardness is much harder than any bullet material, which breaks, consumes and decelerates the bullet to the point where the ceramic backing can stop the bullet totally. Please do not confuse Armour Ceramic with floor or wall tile ceramics. Just as aluminium, lead, copper and steel are all metals, so the range of different ceramics have wide-ranging different properties. MOH’s scale of mineral hardness defines talcum as having a hardness of 1 and diamond a hardness of 10. Ruby and sapphire run at ±8 on this scale while armour ceramics are ±9 on this scale. Although the ceramics are extremely hard, they can be a bit brittle and need to be used in combination with other composite materials to make a solid hard plate which can still provide the required protection, even after it has been hit by previous shots or been bumped against many walls. The labelling on ceramic-based plates generally states “Handle with care. Do not drop”. This is so, and just like I do not park my car by driving it into the garage wall every night, knowing it will not totally disable the car, I will treat the car and plate with care, knowing it cost money, and its integrity and condition might save my life at some stage. I will therefore treat ceramic-based, and for that matter, all body armour plates and components, with care.
The table below compares the weight and relative price of the materials discussed to provide protection against the most common local rifle threats (R4, AK-47 and R1) when used in conjunction with Level II soft armour. All these values are based on a plate of 250 x 300mm size with “Shooters Cut” top corner cut-aways.
From this comparison it is clear that, to save weight, it will be necessary to pay more per plate.