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Stored in direct sunlight for many ears?

On 11/09/2018, Tim Gillett <[log in to unmask]> wrote:
> Hi Peter,
>
> Is it possible the tape had been reshelled at some point, or some
> combination of parts assembled together?
>
> Tim Gillett,
> Perth,
> Western Australia
>
>
> ----- Original Message -----
> From: "lists" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Tuesday, September 11, 2018 6:14 AM
> Subject: [ARSCLIST] very strange/unique decay found on u-matic
>
>
> Today I received a พ" u-matic tape with the strangest damage I have ever
> seen and was wondering if anyone else had seen something similar or had an
> idea what might have caused it.
>
> We have processed nearly 500, 000 tapes and we do quite a lot of disaster
> recovery.  I have seen tapes that have been exposed to virtually every
> negative influence imaginable (and some not so imaginable) so I was quite
> surprised to see something totally new.
>
> The tape:
>
> The tape is a 3M UCA-60 from 1984.  The cassette and hubs are white(ish)
> plastic and the interior posts/guides and the door lock mechanism are made
> out of black plastic.  The access door is anodized black metal.
>
> The damage:
>
> The tape is entirely discolored where exposed. The discoloration is only
> near the edges a few wraps into the tape.  I have not spooled  the entire
> tape yet to determine how far the discoloration continues.  The metal
> cassette access door shows many small spots of corrosion on the inside of
> door where it would be closest to the tape.  There is no corrosion on the
> outside or the edges of the door. The tops of the metal screws on the back
> of the cassette are badly corroded.  The entirety of the black plastic tape
> guides and black plastic door lock mechanism are very brittle/damaged, to
> the point where they are falling apart and partially missing/destroyed.
> There is no other indication of damage. The white plastic shell and tape
> hubs are intact and clean and the plastic slip pads inside the cassette are
> undamaged.  There is no staining, no warping, no breakage and no
> brittleness
> anywhere else. Whatever happened, only the exposed tape and the black
> plastic tape guides, the black plastic door lock, the inside of the metal
> access door and the metal screws were affected.  Everything else looks
> fine.
>
> The damage to the tape "could" be consistent with either exposure to liquid
> or heat,  but-  there is no staining anywhere or damage to the paper label
> to indicate liquid contamination and there is no brittleness or
> deformation/melting anywhere else to indicate exposure to high heat.  The
> overall damage is not really consistent with either liquid or high heat
> damage. I even considered the unlikely possibility that the tape was
> contaminated with some corrosive element during playback/rewind and the
> posts were damaged as the tape was wound into the cassette.  This could
> explain why plastic guides are nearly destroyed and the metal access door
> was only corroded inside, near the tape, and nowhere else.  This,
> unfortunately,  doesn't explain the corrosion on the screws and heavy
> damage
> to the plastic door lock mechanism, however, since neither of these parts
> ever touch the tape.  The plastic hub flange and slip pads inside the
> cassette, which do contact the tape, are also undamaged.
>
> Ok, how about some highly corrosive gas that reacts very aggressively with
> one specific type of plastic (the guides and door lock mechanism) and
> uncoated metal (the screws) but doesn't react at all with any of the other
> plastics in the shell/ hubs/slip pads and/or with anodized metal and reacts
> differently with the plastics in the tape (or maybe the metal in the tape?)
> in such a way as to produce a byproduct that corrodes nearby anodized metal
> (the inside of the cassette door) but dissipates quickly (so the rest of
> the
> anodized cassette door is unaffected).  Sound crazy?  Yes it does.  The
> damage is so very specific and selective that I can't figure out what could
> have happened.
>
> Any ideas?  Magic?  Space aliens?
>
> A very perplexed
>
>
> Peter Brothers
> SPECS BROS., LLC
> 973-777-5055
> [log in to unmask]
> Audio and video restoration and re-mastering since 1983
>
>
>
>
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