From: bill@bilver.uucp (Bill Vermillion)
Subject: Re: Old Recording Restoration
Organization: W. J. Vermillion - Winter Park, FL
Date: Sat, 25 Jul 1992 00:46:35 GMT
Keywords: glass based disks, acetate

In article <4904@gold.gvg.tek.com> chrisc@gold.gvg.tek.com (Chris Christensen) writes:

>I am looking for information on the restoration of old disk
>recordings.  The label on the disk reads "special needled for acetate"
>it is also notes on some of the disks that they are glass based disks.

Glass was used for base during WWII when all the aluminum was thrown up
in the air in the shapes of B-17's B-24s, etc.    Actually glass is an
ideal medium for it's smoothness.  It just has other bad properties -
it breaks.

I have about 50 16" glass acetates - recorded from such places as
Carnegie Hall and Town Hall in NYC in 1944 era.  Got them from an old
recording engineer who started shaving 'wax' blanks for Okeh in 1921.
And traveled throughout the South doing 'mobile' recordings in the
'20s.

He had a 10' long accoustic horn cutter, and a turntable that was
powered by sandbags hung from pulleys in the rafters on stage.   As
long as the bag didn't hit the floor he had speed.

I have had NO problems playing these on appropriate turntables and
cartridges.   The transcription format used a 2.5 mil stylus as opposed
to the 3 mil stylus for 78s.  Just make sure the stylus is in good
shape.


>Some of the disks are what appears to be a coating over an aluminum
>blank.

That was the standard method, and that is what is used to today to cut
master lacquers before plating.


>They also have a ceter hole with three holes in a triangle pattern.

Only one hole is needed, but three are convenient and it was probably
mechanical more sound.

The holes are used to engage the spring loaded pin that comes up from
the center of the turntable.   This physically engages the disk as you
can not have slippage.  This is typical of the Rek-o-Kut and Presto
units.   Other units did not have a center drive.  My RCA7B uses a rim
drive to give variable speed, but it does need the center hole to grab
the disk.   And it has TWO synchronous RIM DRIVE motors to keep the
turntable up to speed.  Of course it is about a 40 pound 16" diameter
1" thick piece of steel.  Not much wow and flutter there with that
mass, particularly at 78 speed :-)


The pin also protruded through the disk and then enaged the bottom of
chuck that turned the feed screw to move the cutter stylus from center
to outside - or outside to center depending on what you are coing.

>Anyone with information about the sucessful playing of this type of
>disk or information of a professional restoration service please Email
>me.

All you really need is a turntable that is FULL WIDTH for the glass.
You do NOT want to crack it.    Be careful that you don't have any
separation of the lacquer.

If they are old they may want to be washed or cleaned.  Use a mild soap
or detergent.  DO NOT use any cleaners for LP, it will probably disolve
the coating.

If the discs are noisy you might try 'wet playing' them.  This works
wonders and can turn a scratchy sounding disk into a quiet disk.

I was able to clean up some Eddie Condon 1944 Town Hall Concerts on 16"
glass that way quite successfully.   If you don't have access to a 16"
turntable, you might check some of the radio stations.   

The units that used to be sold had an arm that placed a small amount of
water with a wetting agent onto the groove area from a 'tone arm'
mounted on the opposite side of the real tone arm.   

But you could get by with a small sprayer or something to put a very
fine coating of water with wetting agent.  Need to penetrate to the
bottom of the groove.

Make sure you have a cartridge that can tolerate this.   I used the
Stanton 500's for this - they also have about 6 stylii you can choose
from.  I know they have a 2.7 mil.  They might have a 3 mil.  They have
1mil and .7 mil conicals.  Use 1mil conical for mono lps.  They also
have elipticals.   Shure also has a wide range.

Have fun!

-- 
Bill Vermillion - bill.vermillion@oau.org
                - bill@bilver.uucp 
                - ..!{peora|ge-dab|tous|tarpit}!bilver!bill