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Step 2: Dissolve the Duplicate Card

There are two approaches to this that I've found. Both involve soaking the card in acetone until you can get to the RFID microchip. The chip is encased in an epoxy blob that seems to be impervious to acetone. The backing for the chip that has the traces on it also seems to not mind acetone. The thing I've found that you have to watch out for is once you dissolve the plastic, is that the chip and backing themselves are not strong at all. Be careful to not bend them, the backing board will break and then you'll be waiting for another replacement card in the mail.

Originally, I scraped off the back and front plastic layers on the credit card until I got to the plastic "core." In my case, my card was a different color than the actual middle plastic core. I threw the whole thing in acetone for about an hour and a half, and was able to pull out and measure the antenna at 30.0 inches.

On subsequent attempts, since I knew the antenna length, I just cut out the small chip area on the credit card. With less mass for the acetone to dissolve, it went faster, probably a little over an hour, and I also didn't have to worry about covering a large container so the acetone wouldn't evaporate. Once a few people make this and weigh in that their cards are the same as far as chip location and antenna length, this step should go a bit faster.

Make sure you don't scrape too close to the metal contacts, and don't scrape too deeply into the back. Once you hit plastic, you're good. The acetone will do the rest of the work.