[78-L] Glass Compound 78s

Tue Jun 16 09:30:30 PDT 2009

albums are notorious for breaking shellac records, glass ones need a 
different home

the diffeerence in color is the different kinds of laminate media used

joe salerno

78records at cdbpdx.com wrote:
> THANKS for all the info about these.  Very helpful.
> 
> The link below shows the label of one of the records I am inquiring about.  You can see an under-label around the edge of the studio label.  Is that label familiar?  
> 
> http://78records.cdbpdx.com/BCO/tn-800_BCO-07_SentForYouYesterday.JPG
> 
> When looking through this record, it is blue, as described.  I have some records that are stamped GLASS on the label and they are red when I look through them.  See link below:
> 
> http://cdbpdx.com/78records/Labels/tn-600_RadioRecorders_5-31-44_SeeThru.JPG
> 
> I am keeping them in a 10 page record album.  Guess I'd better make other arrangements for them.
> 
> Thanks!  CDB
> 
> 
> --- On Mon, 6/15/09, Michael Biel <mbiel at mbiel.com> wrote:
> 
>> From: Michael Biel <mbiel at mbiel.com>
>> Subject: Re: [78-L] Glass Compound 78s
>> To: "78-L Mail List" <78-l at klickitat.78online.com>
>> Date: Monday, June 15, 2009, 10:14 PM
>> 78records at cdbpdx.com
>> wrote:
>>>> Greetings. I am wondering how to easily identify
>> glass compound 78s.
>>
>> I assume you are referring to a glass-base lacquer coated
>> recording
>> disc.  This is a disc that is a sheet of glass with a
>> plastic coating on
>> it that the recording is directly cut into.  
>>
>>>> I was playing a record from 1942 and I noticed
>> the sunlight was sparkling
>>>> off the record in a rainbow of color, as if the
>> light was being reflected
>>>> through a prism.
>> This could happen with an aluminum base lacquer disc as
>> well because
>> that base is reflectively shiny as well, but when you
>> describe it being
>> translucent you can only be describing a glass base disc. 
>>
>>>> I examined the record closely and discovered I
>> could see brightly lit
>>>> images through it. It has an unfortunate crack
>> and the edges of the
>>>> crack seem to be flaking off like glass. 
>> The lacquer coating can flake off like this from any base
>> material,
>> aluminum, steel, or glass.  The dark coating is not
>> itself glass.  If
>> part of the clear glass base is crumbling, then the base is
>> more than
>> just cracked, it is smashed.
>>
>>>> Could this be a glass compound record? Are there
>> any sure-fire
>>>> ways to identify glass compound records besides
>> cracking them
>>>> and looking to see if the edges are flaking
>> off?  Thanks! CDB
>>
>> As dl mentioned, you often -- but not always -- can see
>> light shining
>> thru the translucent discs.  If you do not want to
>> hold the disc up to
>> the light, you can shine a strong light up thru it. 
>> Once you have
>> identified a glass-base disc it should always be stored in
>> a sleeve with
>> a second aluminum-base disc with it, and the disc handled
>> only with that
>> second disc supporting it.  Archives with large
>> collections of glass
>> base discs should have a rule that an aluminum disc be slid
>> into the
>> sleeve and both discs be taken out together.  I was
>> lucky when I worked
>> with the NBC Chicago collection at Northwestern to have a
>> large amount
>> of unimportant aluminum based discs to store with our
>> glass.
>>
>> As dl mentioned, professional grade discs were not marked
>> on the discs
>> themselves, only on the sleeves which often can get
>> switched so that a
>> glass base sleeve could house an aluminum disc, but most
>> home-grade
>> glass base discs are marked on the manufacturer's
>> label.  But glass was
>> rarely sold to the home recording market.  They used
>> steel base and
>> fibre base discs.  Many radio and recording studio
>> labels did mark the
>> discs as glass, but not always because the labels were
>> sometimes
>> prepared by a secretary, not the recording engineer. 
>> The first glass
>> Presto discs were very thick and had a metal grommet in the
>> center hole.
>>  AudioDevices' AudioDisc brand had a fibre-center that was
>> about
>> 2-inches in diameter, and the edge of how this fits into
>> the larger
>> glass hole can sometimes be seen or felt.  Later in
>> the war Presto had a
>> printed label that said glass base, but I am not sure if
>> the discs were
>> shipped with this label on them or if it was to be applied
>> by the user.
>>
>> As to whether glass discs were more flexible when new, I
>> doubt that
>> because one of the reasons glass was used was because it
>> was less
>> flexible than aluminum.  One of the selling points of
>> glass prior to the
>> war was that it was ideal for use for mastering because it
>> remains
>> flatter than metal when being electroplated.  The
>> first glass discs were
>> shipped in early April 1941, prior to our entry into the
>> war, and before
>> aluminum rationing.
>>
>> Mike Biel   mbiel at mbiel.com
>>
>> -------- Original Message --------
>> Subject: Re: [78-L] Glass Compound 78s
>> From: David Lennick <dlennick at sympatico.ca>
>> Date: Tue, June 16, 2009 12:25 am
>> To: 78-L Mail List <78-l at klickitat.78online.com>
>>
>> Very simple..assuming that it's sturdy enough for you to
>> handle without
>> it 
>> breaking (and those things are VERY thin), hold it up to
>> the light. If
>> you see 
>> translucent bluish, yep..it's glass based. As for the
>> flaking, that's
>> not 
>> reversible.
>>
>> If you find this somewhat risky, you can tape the edge
>> lightly with your
>> ring 
>> finger. The sound will be different from tapping an
>> aluminum disc.
>>
>> Not all manufacturers identified glass lacquers, except on
>> the sleeve,
>> which 
>> was pretty dumb. Amazing that 65 years ago, these things
>> were able to be
>>
>> shipped..carefully, yes, but they frequently made it
>> intact. They must
>> have 
>> been a bit more flexible when they were new.
>>
>> dl
>>
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