So, What Materials Can Block an EMP?

EMP’s are far and away the most likely and most plausible of the mega-disasters that preppers ready themselves for.

Be it a manmade nuclear- or non-nuclear EMP strike or a massively powerful solar event, any major EMP event has the potential to instantly transform our high-tech, electronic world into a scene straight from The Walking Dead. Well, without the zombies but you get the picture.

Accordingly, that’s why it’s critical to know what materials can block an EMP so that you can safeguard your precious electronics that can help ensure your survival in the aftermath.

Sadly, there are very few materials that will reliably stop the invisible, nearly instant wave of energy. So, what materials can we depend on to block an EMP?

Several materials can reliably block an EMP, including sheet metal, metal mesh, metal foam, EMF shielding fabric, concrete, and earth. These materials are not equally effective, however.

It seems simple enough, but real EMP protection is anything but. You’ll need to know how best to employ these materials and how thick they’ll need to be if you want to rely on any of them when the fateful day arrives.

Keep reading and we will discuss all of them in detail.

What exactly is an EMP and what are its effects on electronic devices?

An EMP, or electromagnetic pulse, is a sudden burst of energy that can disrupt, disable and destroy electronic devices.

The effects of an EMP can range from temporarily disrupting cell phone service to permanently damaging electronic equipment and igniting power lines. Serious stuff!

While the pulse itself is not directly harmful to people, the effects of an EMP can be devastating to society at large, sending a huge portion of civilization straight back to the pre-industrial era.

A single powerful EMP from a nuclear detonation or specialty EMP generator weapon can knock out entire power grids and communications systems, crippling entire cities across a region.

Common electronics like computers, cell phones, radios, and TVs will not survive an EMP, and nor will anything currently connected to the power grid when it goes off.

For all of these reasons EMP protection is an important consideration for preppers and anyone who relies on electronic devices.

It is possible to protect your gear from an EMP (even if there is no civic electrical service in the aftermath!) and there are a variety of materials that can help you do that through various means.

Most of the time, this means using the materials we are about to talk about as a Faraday cage.

A Faraday cage is an enclosure used to block electromagnetic fields from reaching the sensitive electronics stored within.

A Faraday cage functions by blocking or redirecting the massive energy inherent to the EMP before it can reach the vulnerable electronics stored inside it.

This technology is used in all sorts of high-tech and everyday applications, including microwave ovens, medical equipment, and dedicated EMP-protection hardware.

But that is an entirely different topic for another article. For now, get familiarized with materials that might make the difference when an EMP happens.

Materials That Can Block an EMP

1. Sheet Metal

The most common and perhaps easiest material to use for an EMP Faraday cage is sheet metal.

All you need is some heavy-duty aluminum foil or other solid metal plating and you’re good to go, right? Well, usually.

The trick to using sheet metal for EMP protection is that it needs to be thick enough to actually block the electromagnetic pulse and also form a continual enclosure around the item being protected, with no gaps.

For example, a layer of tinfoil just 0.007 inches thick will only reduce the EMP by about 50%.

To be effective, you would need a much thicker layer of tinfoil or multiple layers sandwiched together.

Considering the ease with which most of these goods can be procured, this is of little concern, and tin foil or thin metal sheeting is so cheap it is possible to make a well-insulated Faraday cage with it for not much money.

Another concern with using sheet metal is that it will conduct electricity, so any electronics inside the cage need to be well insulated from the metal enclosure itself.

This can be accomplished by lining the inside of the cage with a non-conductive material like wood or Styrofoam.

Sheet metal is probably the most popular choice for EMP protection and if you have the means to procure it, this is certainly a good option to consider.

2. Metal Mesh

Another popular choice for EMP protection is superfine metal mesh. The key with using metal mesh is that it needs to have very small openings; very, very small! Otherwise the electromagnetic pulse will just pass right through the gaps.

Whatever mesh you plan on using must be tested before you commit to using it for EMP protection.

Compared to simple sheet metal, detailed above, mesh is a viable choice if chosen with care but can be more expensive and less reliable.

3. Metal Foam

A novel application of metal in the EMP protection role when greater structural strength is needed without an undue increase in weight is accomplished by metal foam.

Exactly what is sounds like, metal foam is metal that has a cellular structure throughout its volume composed of large, gas-filled pores.

Much of the time these materials look like a kitchen sponge but will be as hard as the metal they are made of and far lighter than a solid block of the same metal with same dimensions!

Assuming the pores of the foam are small and the thickness is adequate, it can provide EMP protection akin to the same metal in mesh or sheet form.

This is a great way to create larger enclosures that are strong enough to resist damage and remain stackable.

However, foamed metal materials suitable for EMP protection are usually expensive and difficult to come by, and so their use will probably be limited to the most well-off preppers or only for small, special applications.

4. EMF Shielding Fabric

An increasingly popular choice for luggage, purses, wallets, and other small-scale items designed to block card skimmers and other nefarious tech, EMF shielding fabric can also be effective as a Faraday cage for EMP defense.

These fabrics are made with a mesh of finely woven metal fibers sewn into the fabric itself, and it serves as a flexible and reliable material that also happens to stop electromagnetic fields.

It can be used to craft a variety of containers for smaller items, or even into large covers for vehicles or generators.

Like all other materials, it has pros and cons. On the positive side, it is a relatively light and low-profile material that can be easily shaped and placed.

The downside is that you might be taking the manufacturer’s word on the density and quality of the protective elements and that the same elements might be damaged or degraded from use or carry, unknown to you.

Since many of these products are proprietary, the actual thickness required for protection is not a hard-and-fast rule. You’ll have to trust the maker, but it is telling that most of these bags and cases intended for major EMP threats are about as thick as a heavy wool blanket.

Still, for specialty solutions EMF shielding fabric can be a good option.

5. Concrete

No one’s first choice for EMP protection, even with a skeleton of steel rebar, solid concrete (or concrete-filled cinder blocks do present some impediment to EMPs when thick enough.

The rule of thumb is that the thicker the better, and you’ll need many feet of concrete to meaningfully reduce a potent EMP, anywhere from 1 to 4 feet, though much uncertainty remains as to the effectiveness of concrete alone.

Regular concrete in conjunction with several feet of soil on top is better, and best of all is to still shield the vulnerable gear inside using a Faraday cage, too.

If you already have a proper underground bunker or you live in the middle of a massive concrete structure, it could possibly be enough to save your electronics. If you have any choice, though, depend on one of the options above.

If you already have a proper underground bunker or you live in the middle of a massive concrete structure, it could possibly be enough to save your electronics. If you have any choice, though, depend on one of the options above.

However, development is well underway on specialty EMP-resistant concrete and cement. Relying on a mix of tiny carbon fiber elements (to prevent corrosion without seriously altering the specific gravity of the mix) just 6″ of this concrete is enough to completely block even a powerful EMP.

This, and with no reliance on additional protection except as needed for doors and other penetrations of the structure, e.g. conduits, antennas, etc. It’s expensive and currently a limited product, but quickly becoming a go-to choice for integrated structural EMP protection that still provides the physical protection of typical concrete.

6. Earth

Yes, even good, old dirt can stop an EMP- but you’ll need to be surrounded by many, many tons of the stuff! A few inches of topsoil won’t do the trick; you’ll need to be truly buried for this one to work.

Determinations vary significantly from experts, but your gear must be surrounded in anywhere from 6 to 12 feet of soil to get significant protection!

It sounds foolhardy but consider the practical aspects: If you’re on the far side of a large hill and the source of EMP does not have line-of-sight to you it could be enough to stop it.

Similarly, a shelter that is dug deep into a similar hill, mountain, or underground could present enough of a barrier.

No, you won’t be able to bury your electronics in the garden or toss them in a bag of potting soil and call it a Faraday cage, but you can still factor earth protection into your overall EMP readiness plan depending on your circumstances.