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Is that the main cause for lacquer oxidation? I have found a lot of Audiodisc lacquers,from the 30s and 40s,that are unplayable because of oxidation.

Roger




________________________________
 From: George Brock-Nannestad <[log in to unmask]>
To: [log in to unmask] 
Sent: Tuesday, April 24, 2012 12:36 AM
Subject: Re: [ARSCLIST] Determining substrate of laquer discs
 
From: Patent Tactics, George Brock-Nannestad


Hello,

it was, at least in Europe, and frequently the result is horrible today: the
oxidation of zinc under a lacquer layer might appear worse than that of iron,
because it was more even, and adhesion might be so lacking that the lacquer
curled up in little scrolls ½ inch by 1/16 inch in diameter. Zinc feels
heavier and more limp than aluminum, at least to me.

Best wishes,


George

-------------------------------------



> From: John Dawson <[log in to unmask]>
> > So while we are on the topic, how about Zinc discs?
>
> Good question.  I am not sure if it was every used as a substrate in the
> lacquer era. It might not have had good adhesion and was very heavy.
> But a non-magnetic heavy disc might turn out to be zinc.
>
> Zinc had two places in phonographic history.  Berliner used it in the
> 1890s as material that was acid-etched after a groove in a wax coating
> was cut to reveal the zinc that a bath in acid would create the groove.
> This was necessary to avoid the patents that controlled cutting a
> groove.  The acid created the groove that was actually used for
> mastering or playback.  In the 1920s there was a pre-grooved zinc disc
> that you could put on your acoustical phonograph and when you shouted in
> the horn it would create dimples in the pre-groove which could faintly
> produce sound when played back.  One of these discs had the apt name of
> Echo.
>
> Mike Biel  [log in to unmask]
>