Well, if it stumped you then, it stumped the wizard!
Perhaps the client can shed some light on the situation (Storage
conditions, storage location, etc.) Or, perhaps the content on the tape
(If at all playable) can help.
Please keep us posted,
Corey Bailey Audio Engineering
On 9/10/2018 3:14 PM, lists wrote:
> Today I received a ¾” 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
> [log in to unmask]
> Audio and video restoration and re-mastering since 1983