Body Armor Base Coat vs. Build-Up Coat: Is There a Difference?

A person may want to purchase body armor for many reasons, but it can quickly become overwhelming if you don’t know what you’re looking for. There’s a lot of terminology involved in the self-defense industry that may seem intimidating to newcomers, and two such terms are a “base” coat and a “build-up coat.” But is there a difference between the two?

Base coat and build-up coat both refer to two coatings that are put on body armor plates. Steel plates are typically used as body armor, but uncoated steel may rust or corrode. A base coat is a thin layer with the primary purpose of offering some protection from corrosion, while the build-up coat adds thickness and protection from spalling.

Armored Plates Base Coat vs Build-Up Coat

If you’re in the market for body armor, choosing the right kind of plates can quickly become a confusing venture. If you’re trying to understand something as basic as the difference between a base coat and a build-up coat, you’ve come to the right place. Keep reading to find out whether there is a difference, as well as how to choose the right body armor for you.

Base Coat vs. Build-Up Coat: Is There a Difference Between Them?

Steel plates are a popular choice for many self-defense enthusiasts who want to purchase body armor because they offer decent protection at an affordable price. Plates made from advanced ceramics (like the ones the U.S. Military uses), when combined with Kevlar lined body armor, can stop calibers up to 30.06. Still, such technology is often too expensive for average citizens.

Enter steel plates, which can offer high resistance to penetration. However, steel plates come with several drawbacks, chief among which is their tendency to cause the bullet to spall.  This means that, without any additional protection, a steel plate may end up reflecting metal fragments into the person who’s wearing it for protection! 

Protection Against Corrosion and Spalling

We’ll discuss spalling in more detail below, but suffice it to say you don’t want bullets striking your body armor to spall; the pieces of a bullet can ricochet off your plates and go anywhere, including:

  • Face
  • Neck
  • Arms
  • Legs
  • Bystanders

This is where the base coats and build-up coats come into play.

Bullet Impact on Armored Plate with Light Spalling

A base coat is an ultra-thin covering that keeps the steel from rusting. Steel that’s completely unsealed or unprotected tends to rust, even if it’s stored out of the elements. You don’t want your body armor rusted, which is why most body armor manufacturers apply at least a base coat. 

However, a base coat doesn’t offer much protection against the spalling we talked about earlier. Bullet fragments (shrapnel) tend to travel perpendicular to where they strike steel, but a build-up coat helps to transfer some of that energy to reflect shrapnel away from the point of impact. It also adds some weight and thickness to the plate.

How a Bullet Reacts to Hitting Metal

If you’d like to see a quick video of how bullets react to impacting on solid steel, here’s one. As you can see, the bullet doesn’t change its shape; it shatters into a bunch of little pieces, called shrapnel. As you can also see, those pieces of hot, sharp metal fly everywhere. If you’re wearing a solid steel plate, a bullet is going to react the exact same way.

However, it’s not as simple as shattering. If the bullet isn’t a large enough caliber to actually punch through the steel, the round’s outer parts will liquefy because of how fast they’re traveling. However, the core of the round won’t liquify but will instead shatter, sending shrapnel flying everywhere. This is referred to as spalling.

What is Spalling?

Spalling is the fragmentation of a bullet when it impacts something that’s too hard for it to penetrate, like a steel plate. In this case, the round will break apart and send fragments everywhere. Spalling is also referred to as fragmentation, and they’re the same thing. It’s not good because there’s no way to control where the shrapnel goes without a build-up coat.

Another issue with bullets hitting steel is that sometimes, with higher-velocity firearms, the bullet will transfer its energy through the steel and into the body part being protected. Even though the steel plate isn’t punctured, the energy from the projectile hitting the steel plate can result in internal bleeding or broken bones. Later, we’ll discuss how the build-up coat can help with this.

Other Ways to Protect Against Spalling

Besides a build-up coat, there are a few ways that people protect against spalling. These methods are summarized below:

  • Kevlar body armor
  • The primary way that self-defense enthusiasts protect against spalling is by using body armor that’s lined with Kevlar. Kevlar is a very strong type of plastic weave that, while it isn’t bulletproof, can help protect against shrapnel.
  • There are also Kevlar sleeves that slide over body armor plates that can provide similar protection if your plate carrier doesn’t have it.

What Base Coats Are Made From

Each body armor manufacturer uses a different name for their base coat, but they are all made from similar components. At their core, base coats are a protective coating designed to protect the steel core body armor underneath them. Although you can’t look up their ingredient listings online, a common ingredient in body armor coatings is polyurea.

Why Polyurea Is Used in Anti-Spalling Applications

Polyurea is a synthetic polymer (aka a type of rubber/plastic), that provides a waterproof layer as well as good elasticity, and abrasion resistance. It’s resilient and durable as well, which is definitely something you need out of something that might get shot. Polyurea is also used in the following applications, among many others:

  • Engineering and architecture
  • Industrial coatings
  • Theme parks and water decorations
  • Marine applications
  • Truck bed liners

Its main draw is how waterproof it is, which makes it an excellent choice as a base layer material to protect armor plates from corrosion.

What Build-Up Coats Are Made From

Build-up coats are ostensibly similar to base coats but layered on more thickly. One interesting build-up coat is called PAXCON, developed by Line-X, and used in AR500 body armor plates. This material is a military-grade coating that’s been used in a variety of anti-blast and anti-impact applications, including being used as a coating on the walls of the Pentagon.

PAXCON is an incredible coating that provides two main benefits:

  • Blast Mitigation
  • Anti-spalling protection

It’s been used, in addition to a coating on walls at the Pentagon, in some of the following applications:

  • A coating on body armor plates
  • A coating on military vehicles
  • Other government and military buildings around the globe
  • First responder vehicles and applications, like SWAT teams
  • Mortar mounts
  • Flight simulators
  • UAV launch trailers

PAXCON’s anti-spalling works by “encapsulating” shrapnel and bullet fragments in the coating itself. In other words, it catches the shrapnel and keeps it from flying in all directions. It’s a suitable coating for any surface that’s hard enough to create spalling, and it isn’t only for body armor. Most other build-up coats on plates are similar in their capabilities.

Price Difference Between Base and Build-Up Coated Plates

There is a price difference between the base and build-up coats, but it’s not enough to really make a difference. Build-up coated plates on AR500 armor, for instance, will add an extra $50 to each plate. A build-up coat on Axis Tactical Spartan armor is only $35 per plate. For the amount of extra protection they provide, this really isn’t much of additional investment. 

Do Ceramic Plates Get Base or Build-Up Coats?

Ceramic plates don’t spall, so they don’t need a build-up coat. Likewise, they don’t corrode, so they don’t need a base coat either. They often have an outer covering made from Kevlar to provide a little more impact absorption so kinetic energy isn’t transferred to the wearer. Ceramic does tend to transfer energy from a round to the wearer without the Kevlar.

Steel Plates vs. Ceramic Plates

The main competitor to steel body armor plates is ceramic plates, and for good reason. Ceramic plates are much more expensive generally, but they also can offer protection against different caliber bullets or different firearms than steel plates can. They’re also lighter-weight, though they tend to be thicker and bulkier to offer the same level of protection.

Very briefly, the following table summarizes some of the main differences between steel plates and ceramic plates. Ultimately, most manufacturers carry both types of plates, and they have experts who will work with you to reach the best decision. Just because ceramic plates are more expensive, it doesn’t mean they’re better for every situation. 

Steel PlatesCeramic Plates
Very durable, able to withstand 20+ rounds without crackingNot very durable, usually can only take 2-3 round impacts before they’re cracked. 
Certain calibers, like 2.23 REM, cause more damage to steel platesCertain rounds, like 9mm rounds, may have a heavier impact on ceramic plates
Significantly heavier, but more shooter-friendlyLightweight but bulkier
Less expensive optionMore expensive
Requires a base coat and build-up coat to protect against spallingCeramic doesn’t cause spalling
Steel Body Armor Plates Vs Ceramic Body Armor Plates

Table Data Source:

In sum, ceramic or steel plates are each a great choice for the self-defense enthusiast, and which one you choose will really depend on your personal preference as well as your budget. Ceramic plates are more expensive, but you get the anti-frag and anti-spalling properties of ceramic without having to pay extra for a build-up coat.

Why You Might Want Only a Base Coat

Most of the time, you’re not going to stop at a base coat unless you’re not worried about getting shot, at least when you’re purchasing steel plates. This is simply because the base coat isn’t going to provide more in the way of protection, and it definitely won’t help with spalling mitigation. 

Here are some of the reasons you might only want to buy a base coat on your plates:

  • More concerned about getting stabbed than shot
  • Don’t want to add extra weight
  • You have a body armor vest with built-in spalling protection
  • You just want to keep your plates from slipping in your vest.

Protection From Being Stabbed

If you’re buying your steel plates and you’re not worried about getting shot (which of course begs the question as to why you’re buying the plates in the first place), you can stick with the base coat. Likewise, if you’re more concerned about being knifed, a steel plate is going to stop a knife with or without a build-up coat, so you don’t need to spring for the extra expensive coat.

Don’t Want the Extra Weight

This reason will most likely not factor in for the majority of people since the weight difference is negligible, but it could be a concern. AR500 plates, for example, with a build-up coat weigh about a quarter of a pound more. If you have a front, a back, and two side plates, that’s about an extra pound of weight. Again, not much, but it’s worth it to at least be aware of the concern.

Vest With Built-In Anti-Spalling Protection

Some body armor vests have a base layer with some spalling protection built right into them, potentially negating the need for a build-up coat. There are quite a few vests out there with a layer of Kevlar or similar, heavy-duty fabric inside of them to keep spalling to a minimum by controlling and containing the bullet fragments. 

Besides being integrated into the plate carrier, there are Kevlar sleeves available as well. These sleeves hold the plate, then go inside the carrier, for some added protection. The Kevlar won’t stop a bullet, but it will absorb some of the impacts and, most importantly, catch the smaller, slower pieces of shrapnel bouncing off the steel plate. 

Texture for Grip

One benefit that the base coat provides is providing some texture for your plates. Without texture, they’d just be smooth pieces of metal and they would slip around in your vest a lot more. The base coat gives the vest something to grip

Why You Might Want to Upgrade to a Build-Up Coat

Upgrading to a build-up coat isn’t going to run you much more per plate than just the base coat, but it does provide some extra peace of mind. This is because most build-up coats are specifically designed to reduce or mitigate fragmentation and spalling, whereas the base coat is typically thin and doesn’t do much other than protecting against corrosion and provide texture.

Different Types of Build-Up Coats

Steel body armor manufacturers all have their own proprietary technology with a tech-sounding name for their build-up coat. You’ll find a few body armor manufacturers, and the name of the material they use for their build-up coat, below:

ManufacturerCoating Material
Spartan Armor SystemsEncapsuloc
HighComPolyurea Rhino Extreme
Body Armor Build-Up Coating Material

As already discussed above, build-up coats might cost anywhere from $50-$75 per plate. Many armor manufacturers’ base coats offer minimal spalling reduction, but the base coats aren’t designed for that. In fact, many Youtube videos that decry steel plates use only the base coat as “proof” that steel plates don’t protect against fragmentation. 

This isn’t a fair assessment, as these plates aren’t marketed to protect against spalling. However, a plate with a build-up layer is much better at controlling shrapnel and keeping it contained on the plate. Check out this video if you’re wondering what it looks like to have a round impact on a coated steel plate.

Do Other Types of Plates Get Coatings?

In general, only steel plates get a base coat or a build-up coat. This is because only steel is a hard-enough surface to have issues with spalling and fragmentation. Ceramic plates aren’t hard enough, so they don’t usually get coated. Polyethylene plates, which are plates made from hardened plastic, don’t get coatings either because they’re not hard enough.

However, it’s a good idea to get body armor with at least some protection against shrapnel built into the vest itself. This can provide a little more peace of mind if you’re concerned about a round hitting your plate at an odd angle and ricocheting off into one of your limbs. 

The Bottom Line

If you’re looking for body armor as a way to protect you against potential threats, you should seriously consider spending the extra money to purchase a set of plates with the build-up coat. Even though they sound similar, there’s a big difference between a base coat and a build-up coat, and that difference could mean the difference between life and death in a bad situation.

Base coats are only intended to keep a steel body armor plate from corroding; it’s not going to help mitigate spalling and fragmentation. It is cheaper, but not by much. A build-up coat is much more likely to protect against shrapnel, and if you’re buying steel armor plates, you should really consider getting it added on if it doesn’t come standard. 


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Matthew Osborn

Matt is an entrepreneur who has created and successfully exited multiple companies and brands. Now, he dedicates his time to Legionary, where he produces content on guns, family, and freedom.

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