Do Faraday bags work? There’s a lot of misinformation about what a Faraday cage (or bag) protects against. The basic belief is that Faraday bags are designed to block radio wave transmissions, act as an insulator to protect against electronic currents, block tracking and hacking. Federal agencies and local law enforcement officers use them to protect information and evidence (cell phones or laptops) from being hacked and tampered with. Preppers use them as a precaution against an electromagnetic pulse (EMP) from a bomb or astrological event. Nonetheless, are all Faraday cages and bags created equal and how protected are we really?
Mylar Bags vs Faraday Bags
Mylar bags and Faraday bags look the same so how are they different?
Mylar bags are made of a transparent polyester resin and coated with aluminum. The thickness of the Mylar bag is 3.5 mils.
A Faraday Defense bag has five layers made up of static dissipative polyethylene (plastic), aluminum, polyester, aluminum, and the final coat dissipative polyethylene polyester. The thickness of it is 7 mils.
The thickness and protection from light is apparent in the picture above.
Testing Faraday Bags
I decided to try some basic tests with the Faraday bags before stashing them away and I am so glad I did. The outcome of the tests were surprising! It definitely changed how I’ll be protecting my electronic devices. Supplies used to conduct the tests: tinfoil, cell phones, walkie talkies, a radio, and two Faraday Defense bags. Watch the following video to see if the Faraday bags work.
What is a Faraday Bag Designed to Block?
Not all Faraday bags offer the same protection. The most basic Faraday bags are designed to block electromagnetic interference (EMI). Electromagnetic currents can damage electronics. Attenuation or dB is what you’re looking for when shopping for Faraday bags. Attenuation is the measurement of how effective the shielding is. Anything above 60dB is considered very good protection.
Since the bags failed two out of the three tests, it raised the question: why didn’t they block the radio frequency better?
RESPONSE FROM SELLER:
I would like to address your concerns if possible to help clear up questions:
1. Our listing does not claim to block cell phones or walkie talkies – these are EMP bags for protecting items from EMP frequencies causing damage to electronics (they are not bags blocking cell signals – we do carry a full line of privacy bags if this is what you’re after)
2. Much like lightning will pass on the outside of a car (faraday cage) but not harm inhabitants, so an EMP bag acts as a path of least resistance for EMP frequencies to reach the ground.
3. A car will still easily allow a cell phone call or radio signal, but the car itself can block an inhabitant from a direct lightning strike.
The bags you see above DO NOT block radio-frequency interference (RFI), RFID, GPS, WiFi, or cell phone signals. They are just designed to block electromagnetic interference. There are Faraday bags that provide more protection. Sometimes, they are called privacy bags or blocking bags. These bags are designed to protect devices from hacking and tracking by adding more protection.
After researching and testing the Faraday bags, I’ll be adding extra protection to each electronic device. Each item will be wrapped in plastic to act as an insulator, then wrapped in two layers of tin foil, and lastly placed in the Faraday bags for anti-static shielding.
There are a couple of things I liked about the Faraday bags. First, I like that the bags seal completely. The zip-locking seal also protects the contents from moisture. Second, it’s easily accessible and compact, unlike most Faraday cages.
Ideas on What to Store in a Faraday Bag
- cell phone
- solar charger
- solar light
- radio (NOAA emergency weather radio, AM/FM, shortwave radio, ham)
- external memory devices
- alarm clock
- small DVD player with monitor
- glucose tester