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Author Topic: Twiggy archiving---how to deal with disk media oxidation?  (Read 174 times)

stepleton

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Twiggy archiving---how to deal with disk media oxidation?
« on: June 21, 2020, 08:12:08 am »

Hi all,

I've received some Twiggy disks to back up: the Office System 1.1 tools in French, which I don't think we have archived anywhere.

Unfortunately the disk media exhibits a considerable degree of oxidisation. This doesn't rule out recovery altogether, but at best it makes it more difficult. Here's a photo that shows what's typical for this set of floppies.

The BLU manual has a whole section on "Twiggy Problems", including strategies for degraded media. In particular:

"Original/vintage Twiggy media ca. 1983 tend to have a coating of oxide dust, which quickly builds-up on the drive heads and impedes correct operation. It is important to frequently inspect (and clean when appropriate) both heads of a Twiggy drive when using old media. Cleaning the oxide dust off a disk before inserting it can help reduce head cleaning."

I've wondered about the ways to clean oxide dust off of a disk. Are we talking about compressed air, or wiping with a delicate paper or fabric (e.g. lens paper)? What do people usually do?

Thanks for any advice!
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snuci

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Re: Twiggy archiving---how to deal with disk media oxidation?
« Reply #1 on: June 21, 2020, 08:20:27 am »

Good question.  I have an original FileWare floppy that has severe oxidation only at the access holes. 

I was thinking of creating a 3d floppy disk cleaner similar to this for 5.25" disks but my 3d object creation skills are limited:  https://www.thingiverse.com/thing:2715428  You would be able to wipe the disk with alcohol as the disk spins which is cleaner than trying to clean via the hole, moving the biscuit, then cleaning, etc.

Is there such a thing for 5.25" disks already?

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stepleton

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Re: Twiggy archiving---how to deal with disk media oxidation?
« Reply #2 on: June 21, 2020, 08:56:55 am »

As much as I love the 'propes, and I love isopropanol enough to call it "the 'propes", I'm not confident of using that on a disk! Pages 78-79 of the Twiggy specifications document give a few details of the properties of Twiggy media, but the composition of the magnetic coating isn't described.

If anyone has a copy of the Media Specification document #062-1012, we would probably find the information we need. As it is, if the coating is anything like some acrylic paints, then isopropanol will soften and eventually dissolve it.
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rayarachelian

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Re: Twiggy archiving---how to deal with disk media oxidation?
« Reply #3 on: June 21, 2020, 09:23:13 am »

So I've been wondering about something, are the twiggy heads single sided, with a R/W head on one side, and felt pad on the other like on the Sony 400k? Is that why there's two of them rather than single arm with two heads?

If so does that felt cause wear and tear on the media over time?
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stepleton

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Re: Twiggy archiving---how to deal with disk media oxidation?
« Reply #4 on: June 21, 2020, 09:28:24 am »

Yes, that's exactly how it's set up.

I'm curious about that felt, too. The BLU docs talk about cleaning the heads, but surely the oxide material must collect around the felt as well. Do you have to clean those pads, too?
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Al Kossow

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Re: Twiggy archiving---how to deal with disk media oxidation?
« Reply #5 on: June 21, 2020, 10:13:31 pm »

Never use IPA on floppy media. The only thing I would suggest using is Cyclomethicone

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stepleton

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Re: Twiggy archiving---how to deal with disk media oxidation?
« Reply #6 on: June 22, 2020, 04:23:52 am »

Thanks, Al. I'm starting to research magnetic media cleaning now, although much of what's out there has to do with magnetic tapes. Do you know of any recommendations for how cyclomethicone ought to be used, or any other kinds of advice based on your own experiences?
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Al Kossow

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Re: Twiggy archiving---how to deal with disk media oxidation?
« Reply #7 on: June 22, 2020, 09:08:23 am »

If you aren't going to open the jacket up, I just apply a little to the surfaces, rotate, and apply a little more.
It is slippery and spreads pretty quickly, which is why you don't want to use a lot.
It also will evaporate slowly unlike alcohol.

Experiment on some 5" PC disks you don't care about.
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stepleton

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Re: Twiggy archiving---how to deal with disk media oxidation?
« Reply #8 on: June 22, 2020, 05:29:26 pm »

Thanks for the info. Now, apologies for being a bit obtuse here, but I should have asked earlier---what does this stuff do?

If we're adding and rotating, is it mainly a lubricant? Those old disks can be difficult to turn. Or does it clean by helping the jacket absorb or wipe additional oxide muck off of the surface of the disk? Or both...

Some guides for cleaning VHS tapes suggest wiping with a microfibre cloth. I suppose we would do the same here. Experimenting with a throwaway 5.25" disk seems wise.

Meanwhile, other recommendations for tape conditioning equipment and supplies are interesting or of their time. This NIST document describes machines with blades that scrape against the tape surface (like a zamboni) or fun solvents like freon or xylene. I'll take this other stuff.
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stepleton

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Re: Twiggy archiving---how to deal with disk media oxidation?
« Reply #9 on: June 22, 2020, 06:33:19 pm »

I will dump some further findings here, without intending to challenge any advice offered so far. I suspect that lots of people turn to common household alcohols in part because they are often on hand. I have seen cyclomethicone advised for tapes before, but it's probably not something that a lot of people have around the house. Anyway, on to the search results:

Here is how the University of Michigan Library did it for mould (70/30 ethanol/distilled water solution):

https://www.lib.umich.edu/blogs/bits-and-pieces/mold-weird-part-1
https://www.lib.umich.edu/blogs/bits-and-pieces/mold-weird-part-2

Incidentally, I'm inclined to wonder whether what's wrong with the disks I've got now is mould rather than some other degradation of the material. The disks themselves do smell rather musty. I'm not sure I have access to the same fume hood facilities that they do at Michigan, in any case. I haven't seen other people take such precautions.

Here's someone who will sell you a 3D-printed bracket for holding your disk in place while you scrub it with IPA: https://www.floppycleaner.co.uk/
A lot of people seem to like IPA. Fewer people like soapy water.

They like diluted IPA over at the Rand Corporation, for example: https://osf.io/yvdrh/
The Kryoflux folks seem to recommend a 40% mixture themselves: http://www.kryoflux.com/download/kf_525modded_manual.pdf

And that's all I have time for this evening...
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sigma7

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Re: Twiggy archiving---how to deal with disk media oxidation?
« Reply #10 on: June 22, 2020, 07:12:57 pm »

I found the original jackets have much more liner friction that a more modern 3M jacket, so putting the media in a new jacket is always my first step (make sure you note which side is up  ;D )

I think the biggest problem with the dusty disks is how fast the heads collect it, which renders them unable to operate properly. So cleaning often (eg. after each scan of the disk) may be required. At least inspect often and don't assume the rear head is clean just because the front one is.

I expect clogging of the felt pads will accelerate wear, but I'd guess it doesn't interfere with reading the way that dirty heads does.

I also expect that the dust will accumulate on the jacket liners where the soft foam pads press on the jackets; I've disabled those pads to minimize this and reduce jacket friction. As far as I know, no other floppy drive design has those, so I figure they aren't necessary.

Originally I disabled the foam jacket pads to get the disks to turn as the old belts would slip so easily; I've been working on a 3D printed belt tension idler to address this (which will be published at some point, but if you want to volunteer as an alpha tester and have a 3D printer, lmk). If you know of a current source for replacement belts, that would be a valuable contribution.




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