Post : Make your own magnetic ink
URL : http://hackaday.com/2012/07/17/make-your-own-magnetic-ink/
Posted : July 17, 2012 at 11:01 am
Author : Mike Szczys
Tags : acrylic, magnetic ink, magnetite
Categories : chemistry hacks

http://hackadaycom.files.wordpress.com/2012/07/magnetic-ink-e1342537260738.jpg

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 (http://b.vimeocdn.com/ts/308/084/308084424_640.jpg) .

Magnetic ink has been around a long time and is most often used in banking (http://en.wikipedia.org/wiki/Magnetic_ink_character_recognition) . 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 (http://en.wikipedia.org/wiki/Magnetite) is used as the doping agent as it has very strong ferromagnetic properties. By mixing it with acrylic medium in a vortex mixer (http://hackaday.com/2011/03/25/stirring-plate-from-usb-enclosure/) 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.

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