Nina Kalinina and Atsuko Go Back to Basics to Build Magnetic Tapes and Floppies From Scratch

Self-described "mixed media artificer" Nina Kalinina and Atsuko have gone back to first principles to built magnetic storage tape capable of recording recognizable audio — and recently expanded the project to include a home-brew 5.25" floppy disk.

"We've made magnetic tape at home, and it (sort of) works," Kalinina explains of the project. "The very first magnetic tapes used iron, which was replaced with iron rust Fe3O4 for Magnetophon, and shortly after replaced with another iron rust, Fe2O3. The tape medium itself, since the 50s or so, was based on 3M Scotch product, but before that it was just paper and glue. I want to experiment with both, but I'll start with the simpler one: Scotch tape, 1/4 inch."

Magnetic storage was a breakthrough for the computing industry, replacing low-density punch-tape and awkward punch-card stacks with easily-portable and relatively high-capacity magnetic tapes — and even allowing the tape to be erased and rewritten. The technology was also rapidly adopted by the music industry, with Sony's cassette-tape-playing Walkman one of the most iconic products in history.

Whether used for analogue audio or digital computer data, though, the tape itself is the same: a strip of flexible material coated in iron oxide, the magnetic properties of which can be flipped on demand and read back later. To start, Kalinina and Atsuko took a simple strip of Scotch tape — flexible and already coated on one side with adhesive — and applied grains of metallic iron. When this didn't work, experiment two used iron powder — but that didn't work either.

"What is less magnetic then iron but still have somewhat similar properties? Rust," Kalinina writes. "Perhaps that was the reason why Magnetophon used it? Applying Fe2O3 to scotch and paper tape. It is really fine rust, and the surface looks nice. It looks JUST like a store bought tape. But it doesn't work?!"

The seventh prototype used a mixture of Fe2O3 and metallic iron powder, and was the first to successfully record audio. The eighth prototype, though, saw the Fe2O3 heated in order to transform it from alpha-Fe2O3 to gamma-Fe2O3 — altering the crystalline structure and getting it closer to the material used in commercial tapes. "it's very loud, but it has lots of large grains of the magnetic material that result in lots of added noise," Kalinina notes. "Looking at the fractions, Atsuko realized that there's lots of iron-looking grains in there. We probably overheated the material. If we can figure out how to make the particles finer, that could help, too."

What really worked, though, was swapping out Fe2O3 for Fe3O4 — known as black iron oxide, or Mars Black. "[This] actually resulted in a very good tape," Kalinina says, before admitting that "cleaning up the Fe3O4 — black pigment — from all over the desk was not fun." A success with audio then led to a "fun lunch break project": taking the same black iron oxide and applying it to a circle of adhesive paper to create a DIY single-sided 5.25" floppy disk.

Sadly, while the prototype disk could be accessed in a floppy drive and even interacted with on a magnetic basis, it proved too unreliable to store data. "It [was] shedding like crazy," Kalinina explains. "That is the most likely reason why the data was so noisy, and the more we tried to do anything with it, the worse results were. We need to invent a way to cover the surface of the DIY floppy to protect it from shedding. [The] plan? Experiment with varnish covers (maybe even nail varnish will work)."

More details on the project are available on Kalinina's Mastodon thread.