Protecting Contactless Payment Cards




About: I'm an engineer and former science teacher who just enjoys good design and making things! I like to think I am creative and want to share ideas with people around the instructables community, there are so ...

RFID, Contactless, NFC or whatever you want to call it, was a game changer when it came to Credit and Debit Card purchasing. This year, Transport for London, who run the underground and buses in the UK capital, launched contactless payment in addition to its 'Oyster' card payment system.

This was really useful, particularly for visitors to the city, but a very real problem appeared; something that TfL termed 'card clash'.

'Shielding' contactless payment cards from your Oyster card/desired payment card protects commuters from paying too much or not paying at all (and being fined). For anyone visiting the fine city of London from abroad, this is a must read, as TfL will refund mistakes caused by 'card clash', but not transaction fees or other costs.

This instructable is entered in the 'Protection' and 'On a Budget' competitions.

Step 1: Step 1: Empty the Wallet

As it says on the tin.... take all the bits and pieces out of your wallet... those receipts, store cards and train tickets do nothing to help your shielding endeavours!

Make sure you note which side of the wallet you keep your Oyster/desired payment card. For this instructable, I normally keep my card on the right hand side. The design can be adapted for either side of a two part, or any segment of a 3

Step 2: Step 2: Measure Shielding Material

Shielding material can be any electrically conducting material with holes much smaller than the wavelength of the tag. For RFID/NFC/Contactless, this is around 20m, so don't worry if there are creases and little holes in the metal!

Copper is the optimal material for shielding. It is used in networking and computing applications for this. For these low power applications, however, aluminium foil is fine.

The shielding material should be the size of the wallet's largest pocket, plus the size of one segment. This allows the card to side to be doubly shielded. When you measure it off the roll, this allows you to fold the material 3 or 4 times. This is fine, and helps if anything.

Step 3: Step 3: Folding

Fold the screening material over, so that it is the internal width of the wallet. The excess should be doubled over in the segment where the desired payment card would sit. Fold the material until it is also the same height of the wallet.

Step 4: Step 4: Insert Into Wallet and Re-fill

Insert the shielding material into the outside pocket of the wallet, with the payment card or oyster card on the outside of the foil i.e. Wallet Material | Card | Foil | other cards and money.

Fill your wallet back up.

Test that the wallet closes, and that all your cards and cash is inside the foil sandwich - except the payment card which should have an unshielded view of the outside surface of the wallet.

Use the wallet, travel safely and save some money too!



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    10 Discussions


    3 years ago

    An advice if you use the system. As you may expect, the card can't be read if the foil is between the reader and the card. What you may find more surprising is that it won't work if the card is between the foil and the reader, but the card is very near to the shielding (aluminium reflects the waves).

    The important thing about that is that your transport card should never be too near the aluminium foil. Else the card won't work. Leave about 2-3 milimiters of separation


    4 years ago on Introduction

    The payment card system needs much work! The design is defective or intentionally proprietary. Unless these problems are eliminated, another technology will replace it in time.

    1 reply

    I think it's one of those situations where it 'seemed like a good idea at the time'. Unfortunately there were a few too many assumptions made, e.g. people would only have one card; no-one would try to steal information etc.
    For now, we'll have to invest in shielding wallets or fixes like these!


    4 years ago

    an other option is a big as magnetic strip in your wallet, you never be able to pay, but it wil also screw al your cards

    1 reply

    Reply 4 years ago

    thanks for the comment rint.

    true, a magnet would work, but the main point is that you want to be able to pay, just with a single card...

    if you screw all your cards you wouldn't be able to travel on the underground at all... the ticket barrier just wouldn't open!


    4 years ago on Introduction

    This is brilliant, you get my vote.

    i have a question, I am from Germany, and what does it mean leave 1 payment card outside?

    my daughter told me to wrap all my cards in aluminum foil????

    1 reply

    Reply 4 years ago

    thanks for your comment! I hope you figured it out! if not, the idea is that all the cards are surrounded except for the one you intend to pay with... so you can still go through ticket barriers etc by putting your wallet to the sensor, but it only charges one card. to protect against identity theft etc, you'd wrap all of the cards.