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On Tuesday, January 08, 2008 11:40 AM, Linda Reib wrote;

> We located a box with 4 glass based records. Initial investigation 
> shows that they are speeches from the 1940's. I am not familiar with 
> this type of media.

The media is referred to as Electronic Transcription (ET) discs.

Electronic Transcription discs pre-date magnetic recording (ie. wire
and magnetic tape).  ETs consist of a substrate (fiber, aluminum,
steel or glass) coated with a soft material (nitrocellulose) in which
the grooves are cut.  ETs were used to record performances and talks 
in the same way that magnetic tape was later used.

The glass substrate is particularly fragile.  If the discs are 
shipped, good packaging and double boxing are required.


> 2 - are 78's and have been transferred to cassette in 1988. The 
> glass recordings seem okay at first glance (novice opinion). I 
> did not pull the records out of the sleeves. The cassettes are 
> in questionable condition (dirt w/ possible rust).

In this case, I would recommend transferring from the original 
disc rather than trying to preserve the cassette.  If the discs
are in good condition, this may be more cost effective than 
trying to preserve the cassettes.  Ideally, you might transfer
both and see which media provides the best results, since both
the discs and the cassettes have probably deteriorated since 
1988.  It sounds from your description like the cassettes 
deteriorated more than the discs over the past 20 years.


> 2 - are very large 33 1/3, they have not been transferred. One 
> has extreme flaking of the top coating as I looked into the 
> sleeve.

These discs are only going to continue to deteriorate.


> All 4 are stored in acid free sleeves, but it a box so large 
> that they slide around.

If you have sleeves that are of the appropriate size for the discs,
and it is only the sleeved discs that are sliding in the box, then
some padding between the sleeve and the box to prevent sliding is
all that is needed.

Perhaps an archivist on this list may be able to suggest an
appropriate padding or filler.

Otherwise, splitting up the discs by size and placing them in
appropriately sized boxes may make the most sense.


> Could anyone recommend what to do next? Our goal would be 
> preserve and transfer the sound track if possible. I would 
> like to know how to store or re-box these items to stabilize 
> their condition right now. I would then work on finding a lab to 
> transfer the recordings to a usable media.

Acid-free sleeves are the correct way to store ETs.  ETs degrade
by several modes: (1) thermal expansion and contraction, (2)
hygroscopic expansion due to attraction of moisture, and (3) 
palmitic and stearic acid formation which is an autocatylitic 
reaction (ie. once started, it accelerates).  Environmental 
conditions are therefore very important: (1) stable temperature,
(2) low humidity, and (3) acid-free sleeves.

Question: do you see any white waxy substance on the surface
of the disc?  Sometimes it looks like a whitish haze or dust,
and other times it can appear like a waxy coating.  If you do
see this, then you have palmitic and stearic acid formations
on the disc surface, meaning that your disc(s) are deteriorating
more rapidly.


> Is it even possible to save the two 33 1/3 recordings?

Perhaps some, but unclear how much.  It depends on how much of the 
laminate remains adhered to the glass substrate, and in what condition
that remainder is in.  There's pretty much no way to tell in advance
without an audio expert inspecting the actual discs.

There are new imaging technologies that will be available in the
future that may or may not be able to handle badly deteriorated 
discs.  The question is, do you bet on the discs surviving until
such technology is available to you (unclear whether it will work
or not on discs in bad condition), or do you proceed in saving
what you have now.  I would assume that broad access to new 
technology is at least 3-5 years away while it is being proved 
out and refined by a few organizations in the meantime.



Eric Jacobs

The Audio Archive, Inc.
tel: 408.221.2128
fax: 408.549.9867
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