Typically the difference is quite apparent. Labels are a clue. Tapping
the disc gently as suggested is another. WARNING: tapping a glass based
disc may damage a disc, especially if a crack under the laminate has
begun. Shining a light thru the disc will tell you if it is glass. Glass
will shine thru a glass based disc, but not aluminum. Glass records are
best supported by placing another record or stiff cardboard underneath
it, especially 16" transcriptions.
Shellac most probably are commercial recordings and have a printed
label, not hand or type written. There are, to my knowledge, no
instantaneous shellac or vinyl records save for some recent attempts to
make an instantaneous vinyl cutter. Nothing vintage.
Weight can be another clue. Shellac is heavy, especially if it is very
thick. Vinyl less so. Especially if it is quite thin. Shellac is
typically dull, vinyl and instantaneous tend to have a shiny surface if
they have been stored properly and are unworn/undamaged. Vinyl will
flex, shellac not. A warped record is not glass. A shattered one may be
and have sharp edges. VERY sharp.
Instantaneous discs may have only 1 drive hole. Or none. Or they may be
hidden under a label, again the flashlight will help reveal this.
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!
> Tracy Popp
> UIUC Graduate Student MLS