-------- Original Message --------
Subject: Re: [ARSCLIST] Quick ID - shellac, instantaneous, vinyl
From: Shai Drori <[log in to unmask]>
Date: Thu, November 19, 2009 1:10 pm
To: [log in to unmask]

I never thought of this. It's sort of automatic to me and I guess to 
everyone else. The look and feel totally different, that I never spent 
a second thinking about it.

Having handled records for over sixty years, this is generally my
reaction also, except that I have been a teacher and in addition to what
I told my classes about the common items, I have been teaching my
daughter about all of the various media we come across.  Whenever we go
thru records and I spot something unusual I always point it out to her. 
But it comes as second nature to me, even by feel.  I usually can
immediately tell if a lacquer disc is aluminum, glass, steel, or fibre
instantly.  Glass can fool many people but I somehow just know if it is
glass.  They immediately feel different to me, just as Shai also seemed
to know that the discs she handled were glass.  The visual clues include
the edges, the center hole, the weight, as well as, of course, the ring,
the translucency, etc.  There also is a difference in how the light
reflects in addition to transmission thru the disc.  But you can't teach
it -- you learn it by doing.  

There are two variations of glass beyond the normal, by the way.  The
first Presto glass was twice as thick and had a center hole grommet. 
They seem indistructable but they aren't.  When I moved from Missouri to
NJ in 1974 all the glass survived EXCEPT the thick Presto I had.  But it
was a common FDR speech.  AudioDiscs had a fibre center about 2 inches
in diameter.  So the spindle and driving holes are not in the glass but
in that fibre disc.  It is held in place by the lacquer and the paper
labels.  It can fall out, but all you have to do is replace it!  

Mike Biel  [log in to unmask]  
 

 Vinyl is light flexible has a certain shine 
to it and almost no sound when you handle it. Shellac has this sound to 
it when you handle it that sounds brittle, sort of like a "don't @#$^ 
with me". And instantaneous are very heavy compared to the others of the

same size. Of course there are exceptions to the rule but over time you 
sort of just know.
The last time I was puzzled by a record that felt "wrong" was a few 
years back when I got a shipment of glass records. During the War 
aluminum was gone to the army and different substances were used for the

base, glass among them. Never been more scared than handling those 
records and that includes nitrate stuff. The up side was that they were 
ruler flat and played on the emt like a dream, great sound.
m2c
shai

Tracy Popp wrote:
> Hello All,
>
> I have a question on visual identification of, and differentiation among
> shellac, instantaneous and vinyl grooved disks. Are there quick visual and
> non-destructive methods of determining the type of disk?
>
> I am aware that most instantaneous have three "spindle" holes in the center,
> and one can generally determine that a disk is an instantaneous based on the
> core material (if one can see the core material.) Any other suggested
> methods of quick ID and differentiation - barring cracking the edge of the
> disk to see the material composition? Is gently tapping the disk surface,
> and listening for aural cues about material density an useful practice?
>
> Thanks for your assistance!
>
> Best,
> Tracy Popp
> UIUC Graduate Student MLS
>
>