Why Aluminum Blocks RFID: The Simple Science Behind a Metal Wallet
“How does a wallet block a signal?” It is a great question, and the answer is surprisingly simple. It comes down to radio waves and metal, and why aluminum is such a good fit for an everyday wallet.
Contactless cards talk by radio
Your tap-to-pay card has a tiny chip and an antenna loop hidden inside the plastic. It has no battery. When you hold it near a payment terminal, the terminal sends out a radio signal. That signal powers the chip for a split second, and the card answers back with the information needed for the payment.
That whole conversation happens at a frequency of 13.56 MHz and only works when the card is very close to the reader.
Metal gets in the way
Metal conducts electricity. When a radio wave hits a sheet of conductive metal, it creates tiny electrical currents in the metal’s surface that cancel the wave out instead of letting it pass through. The effect is often called shielding, and it is the same idea behind the metal mesh in a microwave door, which keeps the microwaves inside.
When your cards sit between two aluminum plates, the reader’s signal can’t reach the chip with enough strength to power it up. No power means no answer. The card stays quiet.
Why aluminum
You could shield cards with lots of materials, but aluminum hits a sweet spot for a wallet:
- Light. Aluminum is about one third the weight of steel, so the wallet doesn’t drag your pocket down.
- Strong. It protects your cards from bending and cracking.
- Doesn’t rust. It handles sweat, rain and a day on the river.
- Takes color beautifully. Aluminum can be anodized, which builds a hard, colored layer into the surface.
Anodizing and laser engraving
That anodized layer is also what makes our engraving possible. The laser removes the thin colored layer exactly where the design goes and reveals the bright aluminum underneath. You get a crisp white design that is part of the metal itself. It won’t peel, fade or rub off in your pocket, and the engraving doesn’t affect the wallet’s ability to block RFID.
The one tradeoff
Because the wallet blocks signals, you need to slide a card out to tap and pay. Most people find that takes about a second, and it is a small price for knowing your cards are quiet the rest of the time.
Do you need to wrap your cards in foil?
You may have seen tips about wrapping cards in aluminum foil. Foil does work on the same principle, but it tears, crinkles and falls apart quickly. A wallet made of solid aluminum plates gives you the same shielding in a form that lasts for years and actually holds your cards neatly.
Does it block everything?
A metal wallet is designed to block the short-range signals used by contactless cards, ID badges and key cards. It doesn’t block your phone, GPS or Bluetooth, and it doesn’t stop your AirTag from working in our Apple AirTag Wallet, which holds the AirTag in its own spot.
Frequently asked questions
Does the color or engraving change the protection? No. Every color is the same aluminum underneath, and engraving only removes the thin surface layer.
Will it demagnetize my cards? No. Aluminum isn’t magnetic, so it won’t affect magnetic stripes.
Will it set off airport security? Like keys or coins, it may need to go in the bin. It is small and easy to slide through.
Pick your design, pick your color
Every design can go on any of our ten wallet colors, and each color gives it a different look. Here is one design on four colors. Which one would you pick? Try your own combination in the wallet builder, where the preview updates as you choose.
Put the science in your pocket
Every one of our metal wallets is anodized aluminum with built-in RFID protection, holds 2 to 15 cards and has a cash clip on the back. Pick a color and an engraved design in the Laser Engraved Metal Wallets builder or engrave your own logo or artwork on the Custom Image Metal Wallet.
Curious what RFID protection can and can’t do? Read RFID blocking wallets: what they do and what they don’t.
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Design your laser engraved wallet
Slim RFID-blocking aluminum, 10 colors, dozens of designs or your own logo, and a free name on the cash clip. Ships in 48 hours.
