Body Armor Buying Guide

Basic Body Armor Buying and Design Guide

Author: W. Gilliam, Founder, Gilliam Technical Services

info@gilliamtechnicalservices.com

26 SEP 2025

This guide contains many of the issues that I've addressed in previous videos and blog posts.

Whether you purchase armor from GTS or not, we want you to be well-informed about proper testing, and the selection of materials and materials combinations available to meet your goals.

This guide is meant to educate from a layman's perspective and is more focused on ceramic armor plates. For additional, more technical questions, please contact us. 

Please see Appendix A for a list of terminology.  It may be helpful to review the Appendix prior to reading this guide.

Unlike other "guides" which attempt to drive users toward specific manufacturers, this reference attempts to provide the reader with the knowledge to search for and select the proper armor product among qualified armor builders and manufacturers. The objectivity of other guides and buying advice prevalent on social media wanes with affiliate links and other associations.

This guide uses the terms "builder" and "manufacturer" interchangeably.  Armor manufacturing is a process of expert assembly (building).  Manufacturers can be large companies with tens of thousands of square feet, or small specialty shops with just a few employees.  Both can produce quality armor.

Nothing in this guide should be construed as a specific recommendation for your own protection.  Every decision is personal and the outcomes associated with your choice are yours alone.  We are not liable for any consequences resulting from your selection of armor.

This guide will be updated to correct errors and periodically to add new information.

About the Author

My experience with body armor is extensive.  I served as a police officer for five years and began building armor over twenty years ago. Ceramic armor became my focus in 2014.  I have built thousands of armor plates with various ceramic, polyethylene and adhesive materials.  Much of what I write here are the results of lessons learned through the years.  Some manufacturers will not disclose some of the information in this guide.  I feel that it is urgent and relative to dissemenate this information on a wide scale.  

I do not use manufacturer names in this guide. The topics of discussion can be linked to manufacturers as the reader sees fit. The goal of this guide is not to point out specific brand names for criticism.  The purpose is to give the reader some insight into what is relevant from a purchasing decision.  

I do not claim to have all of the answers.  What I write here is from my own experience and may differ substantially from others in the armor industry.  These are only my opinions and may not be true in all cases. I have attempted to discuss the below in a depth necessary to assist with consumer decision making and not serve as a scientific paper.

References 

National Institute of Justice Ballistic Resistance of Body Armor NIJ Standard 0101.07

National Institute of Justice Specification for Ballistic Protection Levels and Associated Test Threats NIJ Standard 0123.00

The bird's eye view of the armor landscape

The National Institute of Justice (NIJ) provides oversight of the certified body armor standard and associated testing programs.  For more information about the NIJ, please read here.

Body armor on the US market falls into one of two categories:  NIJ certified armor and non-NIJ certified armor. Let's briefly discuss the two (this is an important section).

NIJ certified armor

NIJ certified armor will have a "mark" on the ballistic tag (see below).

Image 1: Example of the NIJ mark.

Only armor using this specific mark is NIJ certified. You will notice armor product descriptions that read something like one or more of the following:

Built to NIJ standards.

Built to NIJ 0101.07 standards.

Built to NIJ RF1, RF2 or RF3 standards.

Tested by an NIJ certified laboratory.

You may even see a "stamp" or "ribbon" on the product that indicates something like one of the the above phrases.

None of this means that the armor is NIJ certified and listed on the NIJ Compliant Products List (CPL).

What does NIJ certified armor mean?  The first step (after an involved application process) that NIJ certified armor endures is an initial type test involving various mechanical, condition and ballistics testing.  

The initial type testing is supervised by the National Institute of Justice (NIJ) and is performed onsite at an NIJ certified ballistics laboratory.  The initial type test puts the armor through high and low temperature conditioning and cycling, submersion testing, drop testing, label testing (solvent and friction), ballistic perforation back face testing and ballistic limit testing.  In other words, the armor is tested to function in all sorts of temperature conditions and rough handling after which must still perform without any complete penetrations of the armor.  The vast majority of the shots must also register below 44mm of back face deformation (BFD).

BFD is basically a measure of ballistic energy moving through the armor and is eventually focused into the backing plate.  This is often measured in laboratories with calipers after shooting a representative sample while strapped to conditioned clay blocks.  To put it simply, when the armor is tested it cannot penetrate the armor panel and it can only make a 44mm max dimple in the clay block behind the armor.  An example of this process is seen in the video below.

Video 1: The general ballistics testing process (Perforation Back Face Deformation Testing).

The NIJ certified process then requires one plate to be sequestered as a sample and all future built armor of that model must be identically constructed.

The manufacturer must then undergo a facilities inspection, further sampling and then enrollment into a follow-up inspection and testing program (called FIT).  The FIT program requires random sampling of the armor and scheduled facilities inspections at regular intervals.

A buyer should always remember one thing.  NIJ certified armor is the cream of the crop for production line (assembly line) type armor.  It is the pinnacle of armor products designed to show reliability, consistency and proof of performance. Most people should try to purchase NIJ certified 0101.07 armor that is on the Compliant Product List (CPL). NIJ 0101.07 armor has incorporated the latest NIJ standards and testing requirements. The new NIJ 0101.07 CPL will soon be published.

Non-NIJ certified armor

There are instances when companies choose not to produce NIJ certified armor.  Some of these reasons are:

1. Manufacturing of custom armor.

2. Sales volume cannot support NIJ certification testing costs ($25,000 - $60,000 per model with materials costs included).

3. When manufacturers are underbuilding armor without adequate drop protection, adhesive strength or materials layering that can resist the crown shots and other stringent NIJ-related testing requirements.

4. Resellers "flip" imported armor manufactured overseas to U.S. consumers.

There is nothing inherently "wrong" with #1, #2, or #4 as long as the armor is properly constructed.

The manufacture of custom armor requires changes to the layup on almost every armor product produced.  This means that custom armor cannot be included in the NIJ certified armor program or listed on the CPL since all armor must be identical in materials layup and production process. Custom armor can still be produced using methods that meet or exceed NIJ requirements.

The vast majority of manufacturers will certify one or two of their models and not certify others.  The prima facie assumption is that if a company can produce NIJ certified armor then their other armor must be of high quality.  As we will see, this is not always the case.

Some manufacturers build quality, non-certified armor - and educate their communities about the elements of high quality body armor.  This approach requires an educated consumer that understands complex elements regarding plate weight, types of materials, adhesives, testing, importance of crown shots, etc. Building high quality armor in this way allows the builder to produce NIJ "certifiable" armor but the disadvantage is that the company is not able to leverage the increased financial benefit of offering NIJ certified products. This is a very difficult business model as dedication to quality is often undercut by a competitor's willingness to race to the bottom pricing rung of the ladder.  This approach is also susceptible to being too transparent with build methods and designs, which are easily copied by competitors in a number of ways.  I like to say that "I'm transparent, but not see through!"

#2, #3, and #4 above are intertwined in many ways.  For example, some "reputable" manufacturers specifically build and sell armor that they know will not pass NIJ certified (long-term, repeatable) drop testing. This is done without informing the consumer... and this opens up an unmitigated risk for the wearer. For example, in NIJ initial type testing during the certification process, 25% of all shots must be on the crown (apex) of the armor along its highest point.  Most manufacturers will not test the crown specifically on underbuilt armor and especially will not show historical testing on crown shots due to poor performance. Instead of building an armor plate that can withstand recurring NIJ-like drop tests, they opt to shave 5-6 ounces off the plate weight to enhance marketability.  

Other times, large quantity orders are placed with Chinese or other suppliers, assembled overseas and imported into the United States for reselling purposes.  When most of this armor arrives, it is already assembled - restricting some of the post-manufacturing quality control that resellers can perform.  When armor like this is offered for sale in the USA, it is not possible to certify it under the NIJ program (due to NIJ rules).

Manufacturers and builders can be successful with non-NIJ certified armor.  The only way to do this while maintaining the integrity of the company and its products is to build NIJ "certifiable" armor that meets all NIJ initial and FIT testing requirements under a continuous improvement process.  This sort of dedication will always promote testing, analyzing and identifying gaps between NIJ certified and currently produced armor so that products are constantly improving.

Important aspects of ballistic testing

Understanding ballistics testing is absolutely prerequisite to your body armor decision making process. I want to reiterate this point.  Understanding what is in and what should be in ballistics testing reports is absolutely paramount to your safety. I feel this is especially true with hard armor plates because so much hard armor information can be disguised on reports through manufacturer special requests.  It is also urgent that you understand practices that some resellers and manufacturers engage in to obscure an armor's true performance.

Let's start with the basics.

Must have information in a NIJ-certified lab report includes (refer to Image 2 below):

1. The standard being tested against

This should preferably be NIJ 0101.07 since this is the latest standard.

2. Date

The date is important because it can establish a test within a series of tests on the same model.  This shows reliability and redundancy in design.

3. Manufacturer's name

Is the manufacturer reputable?  Do they have a strong community?  Are they transparent with their social media and testing reports?  Are they constantly engaged in R&D? Do they talk about their failures and successes? Is the manufacturer's name representative of the same company you are purchasing from?

4. Armor model number

The armor model number is important because it limits the reseller or manufacturer from substituting one report for another.  Not all test reports are perfect and you may see a "sample number" under the model number.  However, for transparency, it is best to use the actual commercial model number on professional ballistics reports.  This can provide indications of reliability and performance characteristics over a longer time span.

5. Armor specifics (weight, shape, size)

Weight, shape and measured size are important even if the armor is offered in multiple sizes.  For a hard armor plate, a BFD measurement is typically lower on a larger armor plate than a smaller one.  For example, a monolithic (one piece of ceramic) 11" x 14" SAPI will typically measure less BFD than an 8" x 10" SAPI does with the same projectile and with the same materials layup.  If you see a manufacturer offering you a test report on a 5.9 pound plate versus a lighter cut, say 5.3 pounds - then you should remember that the BFD on the lighter plate will typically be higher than it was on the larger, heavier armor.

6. Mechanical testing (drop testing) and submersion testing

You will not always see this on every test - especially when there is a recent record of that materials layup already having been dropped and submerged. It is a good practice to drop and submerge every time to show consistency in performance. You should at least see this at least once in the testing reports for a particular model. If you only see one example and not able to back it up with additional reports then you should ask what design elements are being utilized to prevent damage during drop testing.

Submersion testing helps test against crude manufacturing techniques that utilize some liquid adhesives, caulk and other materials not suitable for maintaining strength in underwater or moist conditions.

7. Threat type (M855, M193, .30 M2 AP etc.)

This is obviously important as armor designed for one threat may not stop another. If you are buying in accordance with NIJ protection levels, then you will be buying resistance against protection categories (HG1, HG2, RF1, RF2, and RF3). See Table 1 and Table 2 below. If the consumer wishes to stop 1-3 projectiles, then a Special Rifle Threat (SRT) type plate could be appropriate due to a lighter armor weight and/or thickness.

8. Clay temperature and average steel ball drop measurements (19mm nominal +/- 2mm)

Clay temperatures do have an impact on the amount of lab measured BFD. Higher temperatures and higher recorded clay validation drops will increase BFD by up to 4-6mm (see Clay Validation section in Image 2 below). If you are comparing two ballistics test reports, check the clay and drop depths. It is natural for the report with the higher temp and drop depths to have a slightly higher BFD.

As a side note, clay that is "too cool" will act to induce a complete penetration of the armor. This is the reason for the acceptable range of calibration drops being nominal 19mm +/- 2mm.

9.Shot number

Knowing the number of shots can be important. A manufacturer may be testing something specific and may not need to test the maximum endurance of an armor model's ballistic resistance. In fact, total destruction of the armor with multiple shots can sometimes be counterproductive from an analysis standpoint. This is true in cases where a ceramic armor plate model is being evaluated for single-shot resistance to the RF3 threat (as a prerequisite to initial type testing). You would also see a limited shot number when testing the crown of an armor plate or an adhesive's efficacy.

There are other times when seeing multiple shots resisted on a test report shows the viability of the armor's design. For example, a thicker than normal backing material could result in a higher number of stops on lower caliber shots (.223 or 5.56 lead ball for example). This is due to the backing material offering significant resistance to the projectiles versus the ceramic armor strike face.

For RF3 armor, the shot number counts but only when they are in the "right locations." Shooting an RF3 plate off center and not on the crown does not show the true strength of the design. This is misleading and the consumer should always request at least one test report that includes a crown shot. It is common for RF3 armor to resist one or more off-centered impacts and then fail a crown (apex) shot. This is an extremely important requirement.

10. Angle (obliquity)

The shot pattern that the manufacturer chooses may be related to a specific goal. For example, Image 2 below shows the 6-shot, RF3 pattern approved by the NIJ for initial type testing. This pattern is intended to show capabilities at 0° between the projectile and the armor surface and 30°. Angled shots are generally easier to resist because at an angle, there is more ballistically resistant material between the projectile and the wear face. Note the crown shot on the armor as the last shot (armor in its weakest state testing the weakest point).

It is not accurate (technically) to strap an armor plate to a clay backing and shoot it left or right of centerline and call that a 0° shot. Due to the curvature of the armor, there is some angle of incidence between the flight path of the projectile and the armor's surface. A crown shot is designed to hit the amor's highest point at which (theoretically) there is a true, 0° shot and angle of incidence.

11. Velocity

Velocity is super important in ballistic testing. Social media channels can increase the velocity in order to defeat almost any armor. The NIJ has standards for velocities associated with all ballistic threats. Those standards are followed on ballistics testing. You can reference the accepted velocities per threat by looking at the ballistic test velocity section and cross-referencing that with the NIJ 0123.00 (see references section at the beginning of this guide).

12. Measured Back Face Deformation (BFD)

See video 1 for a visual representation of this process. Many things can impact BFD. The general requirement is that armor must show a BFD (for most shots) at or below 44mm. Hard, brittle ceramics (like silicon carbide) can pass energy though the plate in a more focused area due to localized fragmentation. This occurs even though the projectile may be stopped early in the deceleration process. For design purposes, a test result on a ceramic armor composite plate with higher BFD but little PE ply penetration, it could be beneficial to utilize some foam on the wear face to lower BFD.

13. Amount of penetration (complete penetration = failure or partial penetration = success)

The NIJ 0101.07 standard uses the above terms. Labs used to record partial penetrations as "none". Penetrations are now either partial penetrations (stops) or complete penetrations (failures).

14. Specific shot location on the armor  Remember the crown is the weakest part of the armor.  If you have no crown shots recorded, then the known strength of the armor is really not tested. An RF3 ceramic armor plate is considered very strong if it can withstand 2 or more crown shots 3" apart.

A GTS ballistics report is shown below that contains all of the required elements of a proper test report.

Image 2: GTS Model 1023 ceramic mosaic armor resisting 6 shots of .30 M2AP including the last shot on the crown of the armor. The NIJ 6-shot 0101.07 initial type testing pattern shown. Armor was drop tested and submerged in accordance with NIJ 0101.07 protocols.

Make sure you have test reports for any armor you're considering.  For hard armor, make absolutely certain that you have the 14 elements above and that you have drop testing, submersion and at least one crown shot.

Video associated with the written test report is also useful in seeing how the plate reacts to projectiles.  Is there an abundance of ceramic cast off ejecting from the strike face?  For soft armor this is not always necessary.  However, I always recommend that manufacturers physically analyze their own test samples.

Which ballistic threats do you want to resist? In other words, what do I need?

Now that we have discussed the importance of ballistic testing, let's talk about selecting the right protection level for your specific situation.

This is an important question as the answer or answers will steer you in the direction of the most recent National Institute of Justice (NIJ) 0101.07 Ballistic Standards (and associated NIJ 0123.00).  The tables below include the most recent protection categories (HG = handgun, RF = rifle) and associated threats. These tables are taken directly from the NIJ 0123.00 Standard Protection Levels.

Table 1: NIJ HG1 and NIJ HG2 Ballistic Protection Levels and Associated Test Threats and Reference Velocities (handgun threats).

Table 2: NIJ RF1, NIJ RF2, and NIJ RF3 Ballistic Protection Levels and Associated Test Threats and Reference Velocities (rifle threats).

If you only wish to stop handgun projectiles at Table 1 velocities, then you can opt for a soft or hard panel shape.  These can be super light and thin and are normally made of aramid or Ultra-High-Molecular-Weight-Polyethylene (UHMWPE).  Effective armor at the HG1 and HG2 levels can be as light as a pound or so per plate.  You can also purchase bullet resistant vests at the HG1 or HG2 level.  There are two things I want to point out here:

1.  Most bullet resistant products are referred to as "bulletproof".  They are not.  They are designed to resist the specific trajectories, specific weights and specific velocities of projectiles against complete armor penetrations.  

2. When I used to design bullet resistant panels for vests, I would always defer to strong and light UHMWPE (let's just call it PE).  The problem is that PE is susceptible to elevated heat, so contact shots could penetrate deep into 100% PE armor.  Contact shots occur when the muzzle of the weapon is held against the armor and discharged.  The heat damages the PE and violates a number of material plies instantly.  Well-designed PE panels should always have 3-5 plies of aramid on the strike face side of the armor to prevent this.  You can combine this approach with a heat-resistant, stab-resistant layering (aramid combined with stab resistant material) to assist in warding off sharp objects are well.  PE weaknesses are heat and sharp objects but these can be mitigated with well thought out designs.

There are a lot of advanced materials that are light and super strong.  Years ago, I used Kevlar XP 103 panels and the material could begin to stop .44 magnum projectiles in just two layers. Obviously, the panel had more than two layers - but the initial strength of the material was astounding.

Video 2: Example of high performance aramid material used in ballistic vests (handgun).

Most people will opt for a more affordable option when it comes to HG1 and HG2 protection.  This often means selecting a manufacturer that uses 100% PE plies that are bundled (sometimes stitched) and enclosed in some sort of water resistant / UV resistant material (aramid is more UV sensitive).

If you are selecting a HG1 or HG2 product, I highly recommend that something is chosen that is also resistant to contact shots.  100% aramid panels or PE panels with several layers of aramid over the strike face will accomplish this goal.

Additional stab or pointed object protection could be desired, but that option may have reduced significance if you are planning to wear hard armor rifle plates in your plate pockets.

Make sure that you are either buying NIJ certified armor (0101.07 is the latest) or well-tested armor that comes with a complete look at the product's testing history.  Professional, NIJ certified lab ballistics reports should be available for anything you are considering and should comply with this guide in sections related to ballistic testing.

The bottom line is that as a consumer, you have to determine (for yourself) which ballistic threats you want to resist.  It's different for everyone.  Here are some examples:

A traffic officer writes summonses all day.  She works a rotating inner-city shift, placing her in contact with a myriad of challenges throughout the day and night.  Although she believes that HG2 protection is perfect for most circumstances, she may get a call to back-up someone on a robbery or domestic violence call.  As a result, she chooses an RF2 level ceramic armor plate capable of stopping common rifle threats.

A security officer works inside of a concert venue.  They screen incoming guests for weapons using an AI technology or metal detector.  Due to the elevated level of pre-screening, the security officer chooses an HG2 panel for protection because the probability of encountering a rifle threat during his shift is low.

A SWAT officer is part of a warrant team.  He knows he will face rifle threats.  He wants maximum protection against multiple hits with no ceramic fragmentation distractions.  He chooses an edge to edge mosaic ceramic tile array configuration in a single-curve construction for maximum hit protection.

An inner-city patrol officer faces occasional barricaded subject calls.  They caught the last person with M993 ammunition (tungsten core).  This officer wants something super strong that's going to resist almost everything.  He buys an RF3 silicon carbide ceramic armor plate that's substantial enough to resist M993, tungsten core ammunition.

It's important to remember that each choice comes with thickness and weight "penalties."  At a specific price point, the higher the threat level, the more variety of threats to resist - the thicker and heavier the coverage.

It is becoming more common for manufacturers to offer "special rifle threat" (SRT) plates. These uncertified plates rely on ballistic test reports to prove the number and type of projectiles that are stopped. As the vast majority of ballistic encounters involve a single rifle shot to the armor, SRT plates could be something that fits with consumer protection needs.

If you are seeking rifle level protection, it's important to consider the sheer number of M855 ammo that's out there.  I would consider it sound judgement to always be in a position to resist this projectile.  100% PE plates are generally a "no go" in my book because of their vulnerability to these steel penetrators.

RF2 and RF3 armor limitations

A note about steel plates

A "no go" in my book are steel armor plates.  Throughout the years, I have attempted to provide steel with the benefit of the doubt.  But, I have shot steel many times with hunting rounds and the anti-fragmentation coating separates from the steel after one or two shots. 

Steel is very heavy and will not stop the same threats that ceramic can.  Most of the time, people purchase ceramic armor plates due to their ability to stop armor piercing ammunition.  Much of this ammunition is available through various online venues.

I do not recommend steel armor and would never wear steel plates.  As a result, I do not speak to the viability of steel in this guide.  There are others that are steel plate experts and are more knowledgeable about the material and mitigating opportunities than I am. However, in over two decades of being in the armor business, I do not believe there is any more effective rifle protection than a well-designed, composite (ceramic and PE) armor plate.

Here is where we are so far.  The reader has been introduced to the guide, the role of ballistic testing and documentation has been presented, and protection categories and limitations have been explained.  In theory, you should be able to conclude which threat(s) or protection category is most applicable to your needs.  If you cannot, stop here and contact an industry expert for additional information.

The discussion will now focus on hard armor at the RF1, RF2 and RF3 protection categories.

The next step will be to explore the material types of more common ceramics and which one is right for you.  Why is this important? It's important because the type of ceramic influences armor thickness, weight, performance, and price.

Ceramic materials: aluminum oxide (alumina)

Alumina is the most common type of ceramic used in ceramic body armor plates.  It's much lighter than steel and is hard enough to stop most projectiles that you would find on the street.  It is also the most affordable type of ballistic ceramic and offers manufacturers a significant amount of design flexibility due to the purity levels available.  

As a builder, I prefer alumina over other types of materials when it comes to multiple hit performance.  Alumina is not as brittle versus silicone carbide and boron carbide and therefore tends to shatter less.  When evaluating ballistic test performance, we normally see much more strike face damage with harder ceramics than with alumina.  Of course, there are trade-offs with this view - as harder ceramics can potentially resist higher velocity / harder projectiles.  But for materials layups that are designed to meet NIJ RF1, RF2 and RF3 standards, alumina is hard to beat and has some benefits versus the other types. 

One important note about alumina is that a substantial amount of ballistic alumina manufactured in the USA is sold at the 90% purity level.  Lower purity levels are less dense (less effective) and are lighter as a result. Cerco in Ohio produces much of the lower purity (retail) alumina.  Other US-based suppliers include Morgan Technical Ceramics and CoorsTek. These suppliers are comparably expensive and really do not specialize in affordable alumina ceramics.  They tend to focus on hybrid boron and silicon carbide armor for military applications. These companies will quote an order, but the cost is usually many times higher than other quotes for the same or better material purchased from other sources.

Outside of the United States, there are finished ballistic ceramics sources in Europe, South America and China that generally offer higher quality alumina ranging from 95%-99.7% purity.  These levels are available in the USA at much higher costs and significant lead times.  In reality, much of the world's ballistic ceramic powder (raw materials) come from Australia or China.  Despite what many US domestic armor gurus might say, the Chinese are ceramics experts after having thousands of years of experience and offer much higher alumina purity levels at reasonable prices. Any source should be vetted an entered into a quality control program that verifies the ballistic effectiveness of the ceramic.

How is quality evaluated? Quality of materials must be established by the manufacturer and normally includes acceptance inspections, quality reports from the component manufacturer, process of continuous improvement, hazard identification and mitigation, field testing at regular intervals and NIJ certified lab testing.  There are various other methods for aiding an inter-company quality standard and those are generally proprietary methods.

Most high quality, US-based manufacturers acquire their alumina ceramic from Bitossi, in Italy. This ceramic is often in the form of monolithic (single piece) shapes, versus smaller individual tile that is used to create an armor pattern.  The smaller individual tile are often referred to as a mosaic design or ceramic tile array.

Image 3: A monolithic piece of ceramic tile used in the production of composite ceramic armor.

Image 4: Ceramic tile array made from 50mm individual pieces.

On a related note, most manufacturers use adhesives from Pontacol (Switzerland).  Even though some of the big names in body armor claim "100% Made in USA..." the reality is that many of the most important components are imported.  This is not a problem from a quality perspective since the ceramic and the common adhesives are of high quality.

To comply with the Federal Trade Commission's (FTC) Made in America Standard, companies are supposed to qualify their Made in USA claims when a significant component or one or more key elements originate from outside the USA.  Ceramic and adhesives are integral parts of composite ceramic armor systems and the inclusion of these materials from foreign sources should include a qualifying statement.  Made in the USA with Italian ballistic tile would be one proper claim - but is is rare to see compliance with the FTC Standard.  You can read about the requirements for Made in USA claims here.

Alumina ballistic ceramic weight

The manufacturer has a lot of room to design armor with alumina because the available purity levels have a significant impact on density (weight).  For example, the below image shows the density of various purity levels associated with a US-based supplier.

Image 5: Alumina density for various purity levels

To summarize the above table: P90 (90%) alumina has a density of 3.6 grams per cubic centimeter (g/cm³).  P99 (99%) alumina has a density of 3.94 g/cm³. This supplier's spreadsheet does not reflect 99.7% alumina, which has a density of about 3.97 g/cm³ according to quality reports issued with our ceramic. Assuming a square armor panel (for simplicity) of 10" x 12" (120 square inches) at 10mm thickness, the 90% alumina strike face would weigh 6.14 pounds.  The 99.7% tile would weigh 6.78 pounds.  The same sized, 99.7% alumina tile is .63 heavier than the 90% tile.

There are some manufacturers that choose the 90% alumina (in substantial thickness) and then choose a backer that can accomodate the reduced ballistic effectiveness associated with lower purity levels.  This is fine as long as the armor system "works" and there is an even distribution of the alumina material (versus fillers and impurities) that are allocated in a homogeneous way, standardized across the monolithic piece.  The problem arises when the distribution of alumina content is not consistent across lower purity levels resulting in some level of unpredictable performance.

Higher levels of alumina purity increase predictable performance, reliability and alumina distribution throughout the material.  This increased level of redundancy comes at much higher weight... and more expense, since the higher purity ceramic is more expensive.

The above example highlights one of the major differences between manufacturers that often remains unnoticed by most consumers. Well-designed redundancies in armor (especially composite armor) are often hidden until highlighted by failures in inferior materials. An alumina plate may be lighter (even in the same size) but that weight savings is rooted in less pure alumina content. Would you rather purchase a multi-curve 6.9 pound, RF3 plate with a 90% alumina tile or an alternative armor plate incorporating a 99.7% alumina ceramic strike face that weighs 7.4 pounds?  These are questions for the consumer that can only be answered by education, transparency and a close association with your favorite manufacturer. Keep in mind that the vast majority of armor builders and manufacturers will never tell you these things... even when asked.

As referenced above, alumina is the heaviest of common ballistic ceramics.  As a result,  consumers should remember that small changes in actual plate size can have a tremendous impact on total plate weight.  

Example: If we take the example alumina ceramic strike face from above (6.14 pds) and reduce the total size from 10" x 12" to 9.75" x 11.75", the weight of the strike face drops to 5.86 pds.  This is a weight savings of .28 pounds (4.48 ounces).

Many suppliers will manufacture a "10" x 12" amor plate" but use a 9.75" x 11.75", strike face. Then, they will add edge padding or thin rubber along the outer edge to bring the finished size up close to 10" x 12".  There's absolutely nothing wrong with this.  But, it's important for the consumer to understand that when comparing armor plate products, small changes in ceramic strike face size can have a significant impact on overall weight.  In other words, don't automatically discount a heavier armor plate until you find out about the total size of the ceramic strike face and its purity level (if possible).

Chinese (and some US companies) build retracted strike face armor.  Retracted strike face armor is usually built from mosaic tile arrays and is 10" x 12" in total size.  But, the 10" x 12" plate area is not entirely ceramic since there is a 1" eva foam edge around the perimeter of the plate. Almost none of this is ever disclosed to the consumer.  Almost all of the 6 pd - 6.2 pd alumina armor (Level 4, RF3) that is on the market is built with retracted strike faces. Instead of a 10" x 12" ceramic strike face, the ceramic is only 8" x 10" - with 1" foam all the way around the edge of the plate (see image below).

Image 6: Typical ceramic coverage areas on a composite ceramic armor plate

Alumina ceramic armor plates built with retracted strike faces are two pounds lighter than their edge-to-edge counterparts.  Edge-to-edge means that the ceramic strike face extends across the entire backing plate and does not have foam along the plate perimeter.  Consumers should remember that even though retracted strike face alumina armor (1" foam edge) is two pounds lighter, you have reduced rifle protection across the surface of the armor plate due to the retracted amount of ceramic.

Image 7: Retracted strike face mosaic armor. Did you know your "light" armor had 1" of foam?

The subject of weight is complex for normal consumers, especially regarding alumina construction.  You will often see a manufacturer combine some of these elements so that a lighter product can be brought to market.  For example, a company might make a 10" x 12" multi-curved plate out of a 9.75" x 11.75" 90% tile.  As you remember from the above discussion, this does not mean that a heavier, full 10" x 12" 99.7% multi-curve is inferior because it is heavier. In fact, the heavier plate is stronger, more predictable and has more built-in redundancy (plate backing material held constant).

Are retracted strike faces acceptable if disclosed?  I think so... as long as it is clearly explained and the plate backing material has been tested at the HG2 level.  In this way, well-tested retracted armor can be thought of as a sort of hybrid armor plate.  There is rifle protection in the center of the armor and handgun protection along 1" of the armor perimeter.  Once again, this layout's effectiveness is something that you must decide for yourself. I usually recommend edge-to-edge strike face protection unless there is a specific need to do something different.

Just remember that your alumina 6.2 pound plate is light because of less ceramic.  Your friend's edge-to-edge alumina plate will weight anywhere from about 7-8 pounds, but will have complete ceramic coverage.

Alumina armor plate design

This can be an advanced topic, because discussion of all elements can take a long time (and many pages of writing).  Let's try to focus on the most important parts. 

In general, you may have three types of armor plate designs (assume 10" x 12" nominal composite armor sizing):

1. An armor plate that relies on a heavier, stronger ceramic strike face and thinner backing material.

2. A balanced approach.

3. Armor that relies on a thinner ceramic strike face and more substantial backing material.

As a consumer it is very important to understand which one of the three categories your potential plate is a member of. This will heavily influence performance.

#1: This armor is designed to stop two heavy caliber (for the protection level) crown shots and continued effectiveness depends on retention of the ceramic strike face in a usable arrangement.  Pros: Can take a heavy caliber punch, possibly even above its rating.  Cons: Once the ceramic is damaged, the backing plate will be too thin to resist most rifle-rated threats (inferior multiple-hit capability). These are usually heavier plates (8 pounds or so in alumina).

#2: Uses "standard" armor industry layups. We generally expect about 10mm of alumina and 12mm worth of PE plies for a "balanced" approach that will provide some multi-hit capabilities, especially at the RF3 level.  Pros: Generally more multi-hit performance than #1. Cons: Still cannot resist most rifle-rated threats with the backer alone.  These armor plates can weigh in the 7.5 pound range (alumina).

#3: Uses a thinner ceramic strike face and more robust plate backing material that enhances multiple hit capabilities, especially with certain types of projectiles (lead ball).  Pros: This is the lightest configuration of the three types. The armor can stop one crown shot and up to two additional projectiles at the most powerful caliber associated with its NIJ 0123.00 category and still retain enough backing to resist repeated fire from M855, M855A1, M193 and various lead ball ammo (depending on design).  Cons: Cannot generally stop projectiles with diameters greater than the thickness of the ceramic strike face.  These plates are usually thicker than the other two types above.

Which of the above is the "best" layup?  It depends on what your situation requires. I normally prefer #3 because it addresses the primary weakness of ceramic armor.  Here's what I mean.

Most people purchase ceramic armor because it can resist armor piercing ammunition.  Ceramic is lighter than steel and can stop more threats than 100% polyethylene. But, once the ceramic strike face is compromised, ceramic armor quickly becomes vulnerable.  Ceramic is not known as the most effective multiple hit material (both steel and 100% PE are more effective for some types of projectiles).

When a projectile enters a ceramic armor plate (with a PE backer), the ceramic is damaged. When built in accordance with #1 and #2 above, follow-on projectiles in the same vicinity are likely to pass through the armor. 

Design enhancements can limit ceramic armor's susceptibility to grouped shots in the same area of the plate by inclusion of a substantial PE backing plate. This is because the most common modern ballistic threats are from .223 and 5.56 lead ball along with M855 steel penetrators. 

16-20mm of quality PE can begin to resist some M855 on its own (not always by any means).  16-20mm of PE is enough to yaw and resist many AR-15 lead ball rounds.  As a result, you are already in an advantageous position running an RF2 or RF3 armor plate with an 16-20mm PE backer from a multiple hit standpoint.  No matter what happens on the first shot, if you encounter common rounds the backer will aid in multiple hit effectiveness. 

If you add a quality ceramic strike face on top of the above backer and then include a substantial crack arrestor, you can stop more powerful RF2 projectiles and the RF3 threat. Even with damaged ceramic, the solo backer is there to resist common threats found on the street. 

Another advantage to this layup is that the embedded ceramic core of layup #3 provides embedding of the ceramic shards into the backer at the shot location.  This embedded ceramic creates more ballistic resistance than the PE alone.  This further heightens the likelihood that follow-on shots will be stopped.

Disclaimer: This is not a catch-all fix for ceramic armor vulnerabilities and will not always work as described for some calibers and specialty ammunition.

I was a pilot for over three decades and remain a current CFII and Airline Transport Pilot. In aviation safety, we always try to design in as many system safety advantages as possible.  If everything goes wrong, the system is designed to give you the "best chance" at survival.  In this case, layup #3 is the "best chance" opportunity as related to body armor design.

Let's turn now to a discussion about ceramic armor shapes.  This discussion will involve mosaic ceramic tile arrays and monolithics involving how their inherent properties contribute to the pros and cons of #1, #2, and #3 above.

Ceramic strike face monolithics, mosaics and hex shapes

There are several types of strike face configurations used in building modern armor:

1. Monolithic:

2. Mosaic (ceramic tile array):

3. Hexagonal: 

Since monolithic shapes are one-piece of ballistic ceramic, they are a single shape with exact dimensions.  Monolithic ceramic forms are inarguably the most common type of ceramic configuration used in modern armor.  

Armor manufacturing is basically a process of assembly, especially when using monolithic tile.  The process of armor building is fraught with potential pitfalls - so anything that makes an error less likely is generally welcomed.  Having one piece of ceramic reduces the potential for assembly error where cracks (gaps) between armor tiles could exist resulting from improper assembly.  

Monolithic ceramic is very effective against single shots.  They are ideal for RF3 armor design where the goal is to certify armor against a single shot of .30 M2AP.  Compared to other types of ceramic, monolithic forms generally have lower BFD on shot one.  This is due to the size of the armor tile. As the ballistic energy moves through the entire piece of tile, less energy is passed rearward and into the backing material.  There is also a more dispersed area of BFD in shot testing.

Monolithic armor is also more comfortable than other ceramic forms.  Since the manufacturing process for single ceramic pieces can accomodate very complex shapes, building multi-curved monolithic shapes is advantageous and is something not routinely done with mosaic ballistic tile.  The only other viable way to build multi-curve armor effectively is by using ceramic hexagonal (hex) tile or utilizing other materials (steel, 100% PE).

Monolithic tile does not lend itself to complex custom work since the shapes are predetermined.  Another disadvantage is that monolithic tile experience larger "spall circles" on the reverse side of the strike face as compared to mosaic tile arrays.  These increased spall circles tend to thin out the ceramic in a larger diameter (at times up to 6"), reducing the effectiveness of the armor for multiple hits.  This is especially true within 3" of the original projectile entry point.  

Video 3: Some differences between mosaic and monolithic armor

Incoming projectiles will create unpredictable cracking across a monolithic form compared to mosaics.  Mosaics have pre-determined boundaries that act as engineered break points that interrupt ancillary ceramic damage. The unpredictable cracks are both visible and non-visible and effectively weaken the entire plate.  It could be said that a monolithic plate is more predictable on shot one than a mosaic but less predictable in performance on all other shots (as it relates to the function of the ceramic strike face).

Alumina ceramic tile arrays (mosaics) are normally deployed as single curve armor. When constructed properly and in a 50mm size, they are simply the most effective multiple hit armor on the market.  If you focus the conversation on the ceramic layout only - the mosaic ceramic pattern is undefeatable for multiple hit performance.

They generally cannot be used to build multi-curve plates because the bed joints will open up the seam line as the tile accomodate the vertical curvature.  Hex tile are more adept at making this curve and it is possible to use 50mm tile in the lower 2/3 of the plate and hex above.

Mosaics are also quite useful for custom ceramic armor building.  As long as specific piece molds are developed, the pieces can be manufactured in almost any shape and thickness.  Ceramic mosaics have been used in body armor for decades and are also used in vehicle armor, and space-based thermal control systems on the exterior of spacecraft.

Mosaics are cost-friendly compared to monolithics. Alumina mosaic tile is manufactured by powder pressing into "greens" and then heated to almost their melting point in long kilns. Through controlled cooling, the tile obtain considerable density. Most alumina tile arrays are manufactured by technical ceramics companies in China. They are also available in the USA or Italy at similar quality but higher price points.

Mosaics must be assembled, piece by piece.  This makes them labor intensive and their cost advantage evaporates when they are built in markets where workers are paid higher wages.  They are also prone to assembly errors.  It is possible for the mosaic pattern to slide open and gaps emerge between pieces as the tile set-up and cure.  A quality control system must be deployed to guard against this issue.

Mosaics must also be overbuilt.  Given that each piece is only 50mm x 50mm, the ballistic energy is focused into an extremely small area.  This direct energy push into the backing requires a more substantial backing material in thickness beyond what a single-shot monolithic will require.  As a result, mosaic armor (edge-to-edge) is predictably thicker and heavier than monolithic armor.

Some present the idea that the seams between the tile also represent vulnerable points. This could be true in a limited way if they are improperly built. In over 20 years of testing, I have never seen a projectile pass through as a result of hitting a mosaic seam line.  The size of the tile has more influence on performance than the seam does.  Taking this argument to another level means consideration of the consequences after a monolithic plate is hit.  Numerous unpredictable cracks open up - some that cannot be seen.  Every hit on a cracked monolithic plate after shot one would therefore be more of a risk/vulnerability than the well engineered, tight seam lines on a well-built mosaic armor plate.

The use of hex tile exacerbates the tile size versus ballistic energy problem.  In research and development projects, I have seen 10mm alumina in both 50mm mosaic and 30mm hex laid against the same backing material.  When shot with .30 M2AP, the projectile penetrated the hex and did not penetrate the mosaic.  Hex gives the builder amazing flexibility, but the backing material must be substantial (even more than the 50mm tile array).  

I want to mention here that as of the writing of this guide, the Russia versus Ukraine war rages on.  Based on information coming from both sides, being shot is less likely than being hit with shrapnel.  This sheds new light on the wartime probability of being shot more than one time and the importance of hard armor plates to resist more than a single shot.  Although the war is used by some to underpin this argument, the situation on the streets of a violent inner US city is far different than the trenches of Ukraine.  The multi-hit ability of ceramic armor debate will continue to occur... and thankfully, there are product choices for both sides of the discussion.

Comparing Alumina and Silicon Carbide

Crack arrestors for ceramic armor plates

Crack arrestors are one of the most misunderstood and underutilized features of ceramic armor design.  Their proper use is extremely important to overall effectiveness. 

Ceramic armor crack arrestors are strike face treatments. They serve a number of purposes, all integral to maximum ceramic armor performance.

The main components that make a ceramic armor plate "work" are the ceramic strike face, the backing material and the adhesives in between materials layers.  These are the basics.  The materials quality, thickness (ceramic thickness and PE ply count) and choice of adhesives determine the overall quality of the combination.  

As in aviation safety, everything possible should be accomplished in armor manufacturing to address vulnerabilities in design. Although ceramic armor is the world's best material for stopping high energy projectiles (including armor piercing ammo), ballistic ceramic does have a key disadvantage. Once a bullet strikes the ceramic, the damaged ceramic has accomplished its purpose and is no longer very useful. This is especially true when all of the damaged ceramic fragments are permitted to escape via ejection from the strike face during impact.  This ejection process sends ballistic energy in an "equal and opposite reaction" motion back out through the strike face (back through the projectile entry point), creating ancillary damage to tile surrounding the projectile entry point. As a result incoming shot damage, ceramic armor is vulnerable to complete penetrations from additional projectiles in the vicinity of earlier shots.

To address this shortcoming, two strategies can be deployed (among others).  The first one is something mentioned previously and involves creating a more robust polyethylene backing plate.  This takes some performance load off of the ceramic strike face and shares it with the PE, which is a fantastic multi-hit material.  The second technique involves holding the ceramic together so that undamaged areas can continue providing ballistic resistance. The latter is the function of the ceramic armor crack arrestor.

Image 8: Carbon fiber and aramid fiber interweave acting as crack arrestors (green pieces)

Crack arrestors can also help protect ceramic armor against rough handling. The NIJ 0101.07 ballistic standard requires that armor plates be dropped from a height of 48" on a concrete slab while ten pounds of clay is strapped to the wear face.  This mechanical drop testing is performed prior to ballistics testing.  Many manufacturers do not build adequate crack arrestors which can also protect the armor against drop damage.

Various manufacturers simply place a 4-6mm foam pad in front of the raw ceramic strike face for drop protection.  This is not adequate as a crack arresting layer. The strike face protector must be laterally strong and capable of resisting ballistic armor system back pressure.  This back pressure is the release of energy back though the initial projectile entry point.  The crack arrestor must be bonded to the ceramic itself.

The design of the crack arrestor has a significant impact on its performance.  The type of ceramic (monolithic versus mosaic) also steers the crack arrestor (CA) design.  CAs can be light and used to hold ceramic pieces together, or they can be thicker.  Substantial crack arrestors are normally made from PE, carbon fiber or aramid and can help prevent ceramic ejection from the strike face.  It is important to note that low fragmentation ceramic armor utilizing more robust crack arrestors will experience higher BFD when tested due to the trapping of energy within the armor plate.  Normally, this BFD increase is 3-6mm (RF3) and can be influenced by the type of PE in the backer and whether there are composite wear face stiffeners applied to the rear of the armor.

CAs can also protect ceramic surrounding projectile entry points from crack promulgation, especially along the strike face side.  Despite some social media videos claiming that manufacturers "laminate" the reverse side of the strike face (between the ceramic and PE backer) - I have yet to see this on a wide scale or evaluate any benefit from using intermediate materials between the ceramic and PE backing plate. The PE sheet that is present along the reverse side of the strike face in some videos is simply the top layer of the PE backer being sheared off by ballistic energy.

The only way to really know whether CAs are used in your armor is to ask your manufacturer.  You can also view YouTube demo videos or review manufacturer product data, if disclosed.

The idea of "at least one" certified plate

There is a general belief that it's acceptable to purchase non-NIJ certified armor as long as the company has "at least one" NIJ-certified plate. I want to address this because that is not necessarily the case.

It is acceptable to purchase non-certified armor from companies that are transparent, test frequently, and have armor designs that align with industry standards.  As the reader is now aware from reading this guide, there are numerous things that resellers or manufacturers can do to disguise the true quality of their armor.  To recap, some of those problematic behaviors are:

• Reducing redundancies by lowering ceramic purity levels (to save weight).
• Utilizing retracted ceramic strike faces and failing to notify consumers (to reduce weight).
• Making improper Made in USA claims.
• Using ballistic test reports that do not belong to the entity involved.
• Using ballistic test reports that involve alternate models or layups.
• Disguising an armor's true strength by omitting crown shots from ballistics tests.
• Publishing armor weights and sizes with wide tolerances.
• Establishing affiliate links with social media outlets that claim to be objective.
• Pushing SPAM through online discussion boards with select accounts.
• Lack of transparency in armor design, planning, purpose and customer education.

Just because a company has an NIJ-certified plate or two, doesn't restrict them from engaging in suspect behaviors.  The gauge for whether or not a manufacturer, builder or reseller deserves your business should not be based on whether or not other armor models are NIJ certified.  Either buy the NIJ-certified models OR establish a relationship with your manufacturer so that you are confident in the product.  See if they will send you pictures of your armor being made or answer technical questions... or take a phone call.  These are all positive signs.  

Manufacturing techniques and components

The following discussion is very individualized.  From a consumer's perspective, it is important to have some technical knowledge about manufacturing techniques.  Understanding best practices will aid you in understanding your product's strengths and weaknesses.  It may also set one manufacturer or sales outlet apart from the others.

As experience is gained in the armor industry (as a builder, manufacturer or reseller), one sets their own path ahead.  An engineer will have a different view that someone assembling armor components.  Someone evaluating field test results will have different opinions than someone that works in an NIJ certified ballistics lab.  The following are just my opinions and I pass them along for consideration or rejection. I hope they will be of some use to at least consider.

There are many potential failure points when manufacturing body armor.  This discussion will center on ceramic armor plates.

Ceramic

Very few armor manufacturers produce their own ceramic.  There are various sources throughout the world through which quality ballistic ceramic can be obtained.  Many of these sources offer the ability to open molds, providing for some differentiation in ceramic shapes and sizes between manufacturers.

One of the best sources in the world is Bitossi in Italy.  Bitossi is world renown for quality alumina ceramics and is now producing sintered silicon carbide (SSiC) strike faces.  There are many other sources, all with their own styles, and availabilities in thickness and purity levels.  Many well-known US armor brands use Bitossi.  The ceramic tile can clearly be seen in YouTube testing videos with the black informational stripe and qc code along one edge of the ceramic strike face. If you are considering an alumina ceramic armor plate, I highly suggest consideration of the Bitossi ceramic component.

Other sources include CoorsTek, Saint-Gobain, Morgan Technical and Moh-9 Armour Ceramics (Multotec) in South Africa all offer high quality ceramics.  Cerco in Ohio offers alumina tile that is especially popular with one or two US-based manufacturers.  There is also very solid technical ceramics out of China and South Korea for certain types of alumina and silicon carbide (SiC) processing.  

Ceramic is not normally "processed" beyond the point at which it is received by the armor manufacturer. One exception is to bond ceramic mosaics with specialized adhesives that permit some elongation during autonomous tile action.  But the material itself is set and ready for use after uncrating, inspecting and weighing.

Polyethylene (PE)

Most modern ceramic armor is comprised of two, main ballistic resistors: a ceramic strike face and an Ultra-High-Molecular-Weight-Polyethylene (PE) backing material.  Unlike the ceramic, PE must be processed for use behind the ceramic strike face.  PE arrives from suppliers to armor manufacturers on rolls. The material can be various widths but is generally about 64" wide.  It is a finished material ready for processing and much of the PE used in armor applications is "unidirectional" or UD.  For strength, PE fiber is laid together in the same direction and held in place with various types of resins.  Some are layered on top of one another at 90° or 45° angles (for increased strength) or even woven in some cases.  Some well-known PE high-performance brands utilize Chinese fiber into their processed rolls. Those companies usually offer alternative "Berry compliant" PE selections that sources all PE fiber from the USA.  Some military contracts need to be Berry compliant and more can be read here.

Since "off the roll" PE cannot be adhered directly to ceramic and put to use effectively, it must be consolidated.  To "consolidate" PE means to process it from its sheet-like, almost fabric form to a hard backing material. This is accomplished through heat and pressure techniques.

Image 9: Pre-processed roll of Honeywell Spectra 3780.

Video 4: PE after consolidation.

There are two main ways to consolidate PE:

1. Via high tonnage press. Most PE is consolidated by about 1000 ton machines that press between 3500-5000 psi while heating the PE material to approximately 266°F. The actual process used will be a proprietary formula of time, pressure and temperature dependent on PE type, number of plies, resin type and other factors.  Pressing the PE into a mold designed to match the ceramic strike face is the most common method for manufacturing consolidated PE shapes.  

This process has a distinct advantage in that a high force can be applied which generally results in more comprehensive consolidation which holds up well under ballistic stresses (prevents delamination).  

There are disadvantages to the pressing process.  The main one is that once the PE material is consolidated into a hard shape, additional processing is required to bond the ceramic to the hard PE backing plate. This process typically involves reheating the ceramic and PE under vacuum pressure in a commercial oven to activate some sort of adhesive sheet.  Most armor manufacturers use adhesive sheets from Pontacol, a Swiss company. Most Pontacol products require temperatures between 110°C and 130°C to melt.

PE is very sensitive to heat and has a relatively low melting point.  I have worked with PE that has experienced performance degradation at temperatures below the melting point and only slightly above temperature required for consolidation.  An improperly calibrated oven or long periods between 130°C and 147°C can result in PE weakening. This secondary reheating required for bonding introduces an additional element of risk to the manufacturing process. Oven hot spots can result in unpredictable weak spots in the PE backers.

A select few builders have contracted out to chemists for proprietary adhesive blends that mitigate the heat threat by requiring extended dwell times at lower temperatures as a prerequisite for melt. This allows for adhesive activation at lower temperatures but requires slightly longer processing times.

The secondary heating process required of the armor plate bonding process is also problematic since it introduces heat under much lower pressures (generally one atmosphere) which can result in some loosening of the tight ply press achieved during the original press.

2. Autoclaving. This method is becoming more popular and it has the advantage of bonding the ceramic strike face to the ceramic while PE consolidation occurs.  This one-step processing saves time and costs by reducing dependency on molds that have to specifically match the ceramic tile curvature. This provides the autoclave-oriented manufacturer with lots of capabilities to shift between ceramic tile shapes and sizes.

Most autoclave proponents point to research indicating that autoclave use results in a more evenly distributed adhesive layer without air voids.  Use of autoclaves marries up well with recent technological advancements permitting PE consolidation at lower pressures.  There are an increasing number of PE products on the market within this new category.

The real difficulty with autoclaves is the PE delamination that is possible during ballistic impacts.  Some armor autoclaves are operational at approximately 150 PSI max. This is a long way from the 3500 PSI+ achieved by a high tonnage press. Even at the lower end of the pressure scale, most autoclave users are very happy with the performance.  I would recommend autoclave pressure capability of at least 300 PSI.

Obviously, the press and the autoclave work best when bonding PE to monolithic ceramic.  However, there are very effective methods for bonding mosaic strike faces via a commercial oven or autoclave method.  Most of these techniques involve forms and are proprietary.

There are other proprietary methods for consolidating PE, especially involving complex shapes. These methods still involve the elements of time, pressure and heat. 

Manufacturers may choose to operate their own presses or autoclaves or spec the consolidation out to an expert third-party with lots of redundant machinery.  This is a business choice and in my experience (with reputable partners) there is no discernable difference in resultant hard PE shapes between company-owned or outsourced consolidation.  In fact, we have seen the opposite.  Instead of having just one autoclave or one or two presses, having access to significant machinery through third-party access permits redundancy and reduction in business interruption probability.  It also reduces equipment maintenance fees and allows the manufacturer to focus on design, implementation and quality control.

Some companies will consolidate their PE in-house up to a point, and then contract out for additional overflow.  Others will contract out for a portion of the PE consolidation and complete the process in-house.  There are a lot of different options and many different, effective ways of getting to the same goal. Remember that the proof is in the manufacturer's performance as indicated in the proper ballistics testing and transparency.

Overall, there are lots of different types of PE. This gives the manufacturer tremendous design capabilities.  Some are "harder" than others and you will see less BFD on a layup. Others are softer or more moderate and will have more BFD.  Elasticity will result in higher BFD, but will also accomodate the stretching required of multi-hits without inducing complete penetrations.  My favorite PE has a water-based polyurethane resin and is a moderately pliable material that performs well in multiple strike scenarios.

Adhesives

Adhesives are one of the most important elements of a ceramic armor plate. Mastery of adhesives is a must if a company is going to provide strong, multi-hit armor.

Adhesives are not just for bonding ceramic to consolidated PE.  They can also act as tools in reducing risks to the environment, workers and systemic dangers within production elements. For example, powerful, proprietary adhesives with non-detectable VOCs are good for customers, workers and everyone else.

One of the most important parts of building armor plates is bonding all of the materials together into an effective system. For an armor plate to work properly (and safely) the materials have to be kept in close proximity to one another. Any separation in the materials layup results in decreased performance.  The materials only work when they work together as an armor system.  If you shot an RF3 ballistic tile on its own, the projectile would likely penetrate the ceramic and continue along, striking the next thing in its path.  If you separated the ceramic strike face and the polyethylene (PE) backer by 1"-2", you would see marked reduced effectiveness and possibly a complete penetration (depending on the design) of both materials.  Keeping the armor plate bonded encourages all sections of the the plate edges to remain together. This reduces projectile, jacket and ceramic fragmentation parallel to the strike face which could emanate from points between the ceramic and PE backing.

The types of adhesives used worldwide is tied to geography.  Armor built in China normally incorporates super glue or neoprene liquid type adhesives.  Professional armor construction in the USA normally utilizes a thermally activated sheet. There are problems with both.  We have discussed some of these already as they are related to heat.

The issues with super glue (cyanoacrylate) and neoprene type adhesives are their ability to bond effectively with low-energy polyethylene.  These adhesives are manually applied to the backing out of large tubs of pre-mixed adhesive (via squeegee). The ceramic tile is then applied and the armor is allowed to sit until cured.  This process is seen below and accounts for the vast majority of low-priced armor imported into the USA.

Video 5: General methodology for assembling retracted strike face armor

Using a liquid adhesive can have some disadvantages.  The main one is related to the uniformity of the adhesive layer between the ceramic and the low-energy PE backing material.  The more variation in the thickness of this layer, the more difficult it is to predict ballistic energy routing (performance). This variation can also create weaknesses in materials bonding.

For maximum strength, a thermally-activated adhesive sheet may be used.  This produces consistency in the adhesive layer.  Under pressure, this layer will not only be more uniform in thickness, it will also be relatively free of air bubbles. The below image shows an adhesive sheet (pre-processing state) resting between the ceramic and the PE layer.

Image 10: A uniform adhesive sheet resting between ceramic tile and the PE backing material

Most adhesives emit volatile organic compounds (VOCs) until fully cured.  You can locate some manufacturers that use proprietary low VOC, RoHS and/or CA Prop 65 compliant materials.  These types of adhesives are safer to use and they will not have any offensive odors when delivered to consumers.

Fiberglass backing plates

Some manufacturers still produce ceramic armor plates with fiberglass (e-glass or s-glass) backing materials.  These backing plates are heavy and do not resist steel penetrators as well as PE backers.  A couple of reasonably well known brands still use glass backers on some of their products and I would suggest sticking with PE backing materials.

An example armor plate comparison

A consumer wants to purchase an RF3 (Level IV), multi-curve armor plate because he is interested in stopping high velocity, heavy hitting projectiles.  He narrows the search down to the following two products.  He selects Model A because there is an NIJ- certified lab report for a crown shot, likes the higher purity tile and transparency regarding the armor's total weight.

Model A	Model B
RF3	RF3
Full 10 " x 12" size	9.75" x 11.75"
7.1 pounds	6.8 pounds with a ".2 pd variance"
multi-curve	multi-curve
99.7% pure ceramic	90% pure ceramic
NIJ lab crown shot	Two shots in corners - no crown shot

 

Statement about foreign armor

I have tested hundreds of armor plates from around the world built by third-parties.  The vast majority of the armor sold within the United States is made in China.  Is Chinese armor effective?  The answer is simple: performance tells the truth.

My temptation is to end the guide with that statement, but I feel like many readers will end up purchasing Chinese armor and I do want to provide some general advice about what's important.  

Chinese-built armor has some shared characteristics:

• built from mosaic style, tile arrays (50mm pieces)
• incorporates a 1" foam ring (retracted strike face)
• resellers do not disclose the retracted strike face
• weighs 5 pounds for Level 3+ (RF2) or 6.2 pounds (RF3)
• uses liquid adhesives (no pressure or heat in build formula)
• performs on par with most US domestic brands if built by reputable companies
• Some say "Made in USA" but are Chinese brands

Most Chinese armor is sold to US resellers, imported into the US as rebranded products and sold in the market across various online venues.  Most consumers making armor purchasing decisions are extremely price sensitive and most opt for a tested, less expensive, Chinese brand.  

The armor business in America is difficult and cyclical for smaller companies - and really only makes financial sense over the long haul... and when offering NIJ certified armor.  Trying to compete with Chinese-made armor is difficult due to the low costs, but also because consumers really don't take the time to educate themselves on armor specifics.  Plate weight, shortcuts, foam edges - all of these things are important but are rarely considered elements of body armor purchases.  Price low, weight low, green light, GO!  That's the way most decisions are made.

The Chinese use a ceramic mosaic strike face.  This arrangement is great for multiple hit, single-curve armor.  The mosaics are prone to assembly errors that can go unnoticed.  The below ceramic armor plate was made in China. The cover was removed and a photo taken of the strike face.  

Image 11: Showing a poorly fitted ceramic mosaic tile array armor plate

As Chinese (or any rebranded armor from anywhere else) armor is imported, the covers obscure the tile pattern fit.  It is problematic to remove the covers without damaging the plate extensively. As a result, the armor is never disassembled for inspection and quality control.  

Although the 50mm ceramic mosaic is superior to monolithics for multiple-hits, the lack of being able to inspect the tile fit is an unmitigated risk for most companies.  In Image 11, noticed the poor between tile fit that opens vulnerabilities to incoming projectiles.

This vulnerability in tile fit is not because it's from China - it's the result of bad workmanship.  It happens in the US also.  There are plenty of examples of excellent performance on NIJ certified lab tests for Chinese armor.  Some outperform the most well known domestic brands. I am not a believer that all Chinese armor is inferior.  There are also examples of bad performance

Image 11 also shows the 1" foam ring around the perimeter of the armor plate.  The 1" foam ring reduces the 10" x 12" armor plate size to an 8" x 10" area of ceramic rifle protection.  This issue has been discussed above and the real problem is that this is almost never disclosed to consumers.  If it is, the disclosure is vague and something like: partial foam rubber edge. Full explanations that benefit consumers in this regard are almost non-existent.

Almost all imported alumina armor is about 5 pounds for a Level 3+ (RF2) or about 6.2 pounds for Level 4 (RF3).  These weights equate to weight reductions associated with the foam ring around the plate perimeter.  Foam weighs much less than ceramic - so, you will see the weight drop substantially.  10" x 12" edge to edge mosaics are normally about 8 pounds (level 4, RF3) or 7 pounds (Level 3+, RF2).  

The Chinese do not use uniform adhesive sheets.  They use liquid adhesives.  These can be strong enough to resist multiple hits, but are sometimes left uncured in some areas due to clumped adhesives being too thick to dry properly.  The advantage to liquid adhesives is related to speed of manufacturing.  But, there is no pressure applied during the cure which can be disadvantageous to adhesion effectiveness.

Many of the imported armor plates test well against US brands.  Many brands will build solid performance retracted strike face armor, but fail with shear problems when attempting to build edge to edge ceramics due to assembly and adhesives techniques.

Another thing to watch out for is an importer that rebrands armor and claims that it is "Made in USA."  Check their website and social media.  Do they offer to send you photos of your armor being built? Can they prove that they are Made in the USA? Manufacturers should earn your trust with transparency and information.  They should be able to answer technical questions.  If they cannot or will not, then move on. 

Appendix A - Terminology

The following is reprinted from the NIJ 0101.07 Standard, Section 3:

3. Terminology

3.1. Terms and definitions from ASTM standards

3.1.1. accessory, n. – a body armor component that is detachable or removable from the
body armor and is intended to provide extended area of coverage protection against
threats that may include ballistic threats, stabbing, fragmentation, blunt impact, or a
combination of threats. (ASTM E3005)
NOTE: Accessories are typically attachments to tactical body armor providing
protection to areas not covered by the vest, such as the shoulders, upper arms, neck,
sides, pelvis, and groin.

3.1.2. ammunition, n. – one or more loaded cartridges consisting of case, primer, propellant, and one or more projectiles. (ASTM E3005)

3.1.3. angle of incidence, n. – the angle between the test threat line of aim and the line
normal to a reference plane based on the front surface of the backing assembly or
witness panel. See also obliquity. (ASTM E3005)
NOTE: Some standards have used the terms angle of incidence and obliquity as
synonyms, but in this standard, they are defined differently. Figure 1 provides
examples to aid in visualizing the difference between angle of incidence and
obliquity.

3.1.4. applique, n. – a three-dimensional item molded from backing material that is shaped
and sized for testing or conditioning a nonplanar test item. 
NOTE: Some appliques are designed for the purpose of filling the entire space behind
a nonplanar test item; other appliques are designed to assess features of a nonplanar
test item.

3.1.5. armor carrier, n. – See carrier.

3.1.6. armor panel, n. – a component of soft body armor consisting of protective materials,
typically enclosed in a panel cover. See ballistic panel, blunt impact panel, stab
panel. See also panel cover. (ASTM E3005)

3.1.7. backface deformation (BFD), n. – the indentation in the backing material caused by a
projectile impact on the test item during testing. Synonymous with backface
signature. (ASTM E3005)

3.1.8. backing assembly, n. – a backing fixture filled with backing material. For example, a
clay block is a type of backing assembly. (ASTM E3005)

3.2.2. ballistic layup, n. – the specific ballistic materials, and their stitching, order, and
orientation, of the ballistic-resistant item under consideration. Ballistic layup does not
include shaping features for nonplanar armor.

3.1.9. ballistic limit, n. – a measure of an item’s ballistic resistance to complete penetration
expressed as a velocity associated with some probability of perforation. (ASTM
E3005)
NOTE: The item may be a test item, material, shoot pack, body armor, or other
ballistic-resistant product.

3.1.10. ballistic panel, n. – a type of armor panel intended to provide ballistic resistance.
(ASTM E3005)

3.1.11. ballistic resistance, n. – a characteristic of protective equipment or materials
describing their ability to provide protection from projectiles. (ASTM E3005)

3.1.12. body armor, n. – an item of personal protective equipment intended to protect the
wearer from threats that may include ballistic threats, stabbing, fragmentation, or
blunt impact. (ASTM E3005)

3.1.13. bullet, n. – a projectile fired from a firearm or testing apparatus. (ASTM E3005)
NOTE: The SAAMI definition considers bullets to be projectiles fired from rifled
barrels, which differentiates bullets from shot, slugs, fragment simulators, and other
projectiles.

3.1.14. carrier, n. – a garment whose primary purpose is to retain the armor panel(s) or
plate(s) and provide a means of supporting and securing the armor panel(s) or plate(s)
to the wearer. (ASTM E3005)

3.1.15. clay block, n. – a type of backing assembly in which the backing material is Roma
Plastilina #1® modeling clay. (ASTM E3005)

3.1.16. conditioning, n. – a process that exposes an item, prior to testing, to a specified
controlled environment or physical stresses, or both. (ASTM E3005)

3.2.3. complete penetration (CP), n. – the result of a test threat impact if one or more of the
following conditions are met:
(1) any portion of a test threat or a fragment of a test threat passes through the wear
face of the test item.
(2) the test threat is visible from the wear face of the test item.
(3) a hole is created through the test item by the test threat.
(4) for soft armor, any portion of a test threat or a fragment of a test threat is
embedded in or passes into the backing material directly behind the test item.
(5) for hard armor, any portion of a test threat, a fragment of a test threat, or a
fragment of the test item is embedded in or passes into the backing material
directly behind the test item.

3.1.17. controlled ambient, n. – conditions with temperature of 20.0 °C ± 5.6 °C (68 °F ± 10
°F) and 50% ± 20% relative humidity (RH). (ASTM E3005)

3.2.4. crown, n. – location of the highest point of a plate, at the intersection of multiple
different curvatures.
NOTE: Novel and innovative designs (such as those for females) may include
multiple high points and complex curvatures.

3.1.18. fair hit, n. – a test threat impact (on a test item) that meets all specified requirements in a particular test method. (ASTM E3005)

3.1.19. hard armor, n. – an item of personal protective equipment that is constructed of rigid materials and is intended to protect the wearer from threats that may include ballistic
threats, stabbing, fragmentation, or blunt impact, or combinations thereof;
synonymous with hard armor plate and plate. (ASTM E3005)

3.1.20. in conjunction with armor, n. – soft or hard armor that is designed to provide a
specific level of ballistic protection only when layered with a specified model(s) of
body armor. (ASTM E3005)

3.1.21. insert, n. – a removable unit of protective material (soft armor or hard armor)
intended to be placed into a special pocket on a carrier to enhance protection in a
localized area. (ASTM E3005)

3.2.5. label, n. – a material applied to a product and containing information about the
product.

3.2.6. label assembly, n. – the label itself and any clear plastic laminate that will be used to
protect the label.

3.2.7. label system, n. – the label assembly and the substrate to which it is applied.

3.2.8. model, n. – the manufacturer’s design, with unique specifications and characteristics,
of a particular item.

3.1.22. nonplanar, adj. – having features that would prevent the test item from making full
contact with a flat surface; typically used to describe curved plates and armor
designed for female wearers. (ASTM E3005)

3.1.23. obliquity, n. – the angle between the test threat line of aim and the line normal to a
reference plane based on features of the test item at the point of aim. (Adapted from
MIL-STD-3027.) See also angle of incidence. (ASTM E3005)
NOTE: Some standards have used the terms angle of incidence and obliquity as
synonyms, but in this standard, they are defined differently. Figure 1 provides
examples to aid in visualizing the difference between angle of incidence and
obliquity.

3.1.24. over velocity, n. – velocity that is greater than the upper limit of a specified range.
(ASTM E3005)

3.1.25. panel cover, n. – a covering, typically nonremovable, that encloses the protective
materials and protects them from environmental factors, such as moisture, ultraviolet
light, debris, and dust. (ASTM E3005)

3.1.26. partial penetration (PP), n. – any result of a test threat impact that is not a complete
penetration; synonymous with stop. (ASTM E3005)

3.2.9. planar, adj. – two-dimensional in quality such that the test item can make full contact
with a flat surface.

3.1.27. receptor, n. – film or paper of a specified abrasiveness onto which coatings (for
example, ink or protective coating) removed from the specimen are deposited during
the abrasion test. (ASTM D5264)

3.1.28. shot-to-edge distance, n. – the distance from the center of the projectile impact to the nearest test item edge. (ASTM E3005) For soft armor, the test item edge shall be the
edge of the ballistic material. For hard armor, the test item edge shall be the
outermost perimeter of the test item.

3.1.29. shot-to-shot distance, n. – the distance from the center of the projectile impact to the center of any other projectile impact on the test item. (ASTM E3005)

3.1.30. soft armor, n. – an item of personal protective equipment constructed of
pliable/flexible materials intended to protect the wearer from threats that may include
ballistic threats, stabbing, fragmentation, or blunt impact. (ASTM E3005)

3.1.31. strike face, n. – the surface of an armor panel or plate intended to face the incoming
threat. (ASTM E3005)

3.2.10. substrate, n. – the material identical to the external surface of the production body
armor to which the label will be affixed. In soft armor, this will typically be the
ballistic panel cover material. In some hard armors, the substrate will be the plate
material itself. In other hard armors, the substrate will be the plate wrap material or
the “sprayed-on liner” covering material.

3.2.11. supplier, n. – the party that is responsible for ensuring that products meet and, if
applicable, continue to meet, the requirements on which the NIJ certification is based.

3.1.32. test item, n. – a single article intended for testing. (ASTM E3005)
NOTE: Examples may include one panel, one plate, or one shoot pack.
3.1.33. test series, n. – the set of all shots necessary to obtain the required number of fair hits on a single test item or the set of all shots necessary over multiple test items to
generate the required data. (ASTM E3005)

3.1.34. test threat, n. – the projectile, edged blade, spike, or other object that is used in
laboratory testing to impact the test item at a specific velocity or energy to assess
performance of body armor. (ASTM E3005)

3.1.35. under velocity, n. – velocity that is less than the lower limit of a specified range.
(ASTM E3005)

3.1.36. unfair hit, n. – a test threat impact that does not meet the specified requirements in a particular test method for impact location and spacing, velocity, obliquity, or yaw.
(ASTM E3005)

3.1.37. Vx, n. – the velocity at which x% of the impacts by a specified test threat are expected to completely penetrate nominally identical test items when tested according to a
specified test method. (ASTM E3005)

3.1.38. V0, n. – the maximum velocity at which 0% of the impacts by a specified test threat
are expected to completely penetrate nominally identical test items when tested
according to a specified test method. (ASTM E3005)

3.1.39. V05, n. – the velocity at which 5% of the impacts by a specified test threat are
expected to completely penetrate nominally identical test items when tested according
to a specified test method. (ASTM E3005)

3.1.40. V50, n. – the velocity at which 50% of the impacts by a specified test threat are
expected to completely penetrate nominally identical test items when tested according
to a specified test method. (ASTM E3005)

3.1.41. wear face, n. – the surface of an armor panel or plate that is intended to be placed
against or proximal to the wearer’s body. (ASTM E3005)

3.1.42. yaw, n. – the angular deviation between the projectile’s axis of symmetry and its line
of travel. (ASTM E3005)