Make Your Own Magnetic Ink

Here [Catarina Mota] is showing off a ring of magnetic ink printed on a piece of paper. It’s strong enough to hold a disc magnet in place when the paper is raised vertically. This strength comes from mixing your own batch of ink.

Magnetic ink has been around a long time and is most often used in banking. The account number and routing number on the bottom left of paper checks are printed in magnetic ink to allow for automated recognition. Iron oxide is charged by the reader as it passes through. In this case, magnetite is used as the doping agent as it has very strong ferromagnetic properties. By mixing it with acrylic medium in a vortex mixer you end up with a homogeneous ink.

There’s a quick demo after the break that shows how well this printed ring holds the magnet. What are some things for which you would use this ink? Leave a comment to let us know.

[via Make]

12 thoughts on “Make Your Own Magnetic Ink

  1. Would be really interested in discovering whether or not this ink could be encoded, exactly as a magstrip. If so, it becomes really interesting to employ in machine-based operations — like a barcode that only the machine can read. And – here’s the fun part – you can then conceal its presence by the creative application of black paint, leaving competitors scratching their heads trying to figure out how your machine “does it”.

  2. It’d be funny to have home made floppy disks if you could make it work. Probably take a lot of testing, though. You’d need film to paint the ink onto probably though, and have to determine how tracks were made. Could be fun if only to do something that might work.

  3. I once found a toy in the Goodwill that played cards with a small mag stripe on the bottom to answer trivia questions printed on the card, I made replacement cards with some cassette tape glued to 3X5 cards but the tape kept falling off (crappy glue), this would be ideal to make new cards. Also you could make “talking” post cards by putting a stripe on your post card, writing it with a modified Iphone card reader and your friend can read it with the same thing, retro!

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