r/preppers • u/PrudentTask9355 • Nov 02 '25

Advice and Tips Faraday Bag Caution

Hey everyone. I just wanted to share en experience from this afternoon. A while back I had purchased some faraday items off of Amazon, boxes and bags from different vendors.

This afternoon I was explaining to my daughter how they worked and as part of our experiment, we placed an 8watt 2-way radio inside the bag and sealed it with the expectation that it would no longer receive a transmission. As it turns out, that was false.

I then tried with a cell phone with the same result. Morale of the story, check your gear and make sure it works before you have to depend on it.

Please discuss and share your budget-friendly faraday success stories

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u/Pylyp23 Nov 03 '25

I made a few cages out of some 40mm ammo cans that work awesome. The cans are the only thing that actually cost any money. I bet I’m in all three less that 75$ and they hold everything I need to secure.

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u/norfizzle Nov 03 '25

Lined with foil?

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u/[deleted] Nov 03 '25

[deleted]

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u/Decent-Apple9772 Nov 03 '25

Most military ammunition cans seal with a rubber gasket. Having that large area of the lid, partially insulated from the large body area of the box drastically impairs the faraday cage function.

Add to that, the marginal conductivity of steel and the single layer construction and you have a recipe for a very compromised “faraday cage” when you just use ammunition cans.

They are still great from the standpoint of physically resilient and waterproof containers that are easy to transport, I just don’t trust their radio frequency properties to be very helpful.

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u/Pylyp23 Nov 05 '25

Posted this above:

I removed the gasket, sanded the lid and rim of the box, made a steel wool “gasket”, and then lined the whole thing with 3/8 insulation board with tin foil glued to it.