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Q & A: making magnetic tape

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Most recent answer: 11/21/2009
Q:
I have been fascinated with iron, how it oxidizes and how to use it's properties. I read somewhere that rust (the oxidization of iron) is mainly Fe2O3. I also read that this state of oxidization is very weak in retaining magnetism and being electrically conductive. I have tested this for my purposes and found them to be true. I am moving on and have been investigating magnetic tape and magnetic recording. I can not find any "make your own magnetic tape" experiments and before I embark on mine, I am wondering if I can in fact use the rust from iron flakes to coat the tape with? I found that Fe2O3 is primarily what they use to coat the tape with, but how can that be given it's weak properties? thanks!
- lara (age 27)
new york
A:
This is just a preliminary answer. Maybe we can get more details.

One key feature of the magnetic coating on tape and disks is the size of the little particles. Each one is a more or less independent magnet. If they're too small, it's too easy for thermal energy to jostle the magnetism into rotating its direction. Then whatever was recorded is forgotten. If they're too big, it can be hard for the small fields of the recording device to line them up to begin with.

So you may need to check how to grind up the rust to get particles of the right size.

Mike W.



(published on 11/21/2009)

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