MATSUBAYASHI 'Shaolin' Kohji wrote:
> At Tue, 8 Jan 2008 11:23:52 -0500,
> David Lennick wrote:
>> For starters, the only 78s that are truly unbreakable are the ones made
>> for mood music libraries (Chappell, Boosey & Hawkes et al) in the 50s
>> and Capitol's "Superflex" kids records in the 40s. Everything else can be
>> cracked by putting your thumbnails together and pushing up..
>> experimenting this way on unwanted discs is a good way to learn which
>> ones will and which ones won't. Even Decca LPs from the mid 50s to
>> the early 60s will fail this test.
>>
>> Other than that, it may be a matter of what country you're in.
>> Canadian plants kept 78s into 1960 and all but Quality used shellac,
>> while Quality's vinyl was easily cracked.
> 
> At Tue, 8 Jan 2008 13:27:09 EST,
> [log in to unmask] wrote:
>> I've seen some postings suggesting styrene rather than vinyl.
>> More  brittle, I believe.
> 
> Hmmm, so there is a strong possibility that
> early "non-breakable under normal use" 78rpms are not made of
> vinyl but other materials like styrene?
> 
> I have also seen somewhere such 78rpms are made either of styrene,
> or of vinyl whose percentages of materials are different from
> that of later flexible vinyl 78rpms/LPs.
> 
> Anyway, is it possible that the "non-breakable" 78rpms (not
> thin and flexible 78rpms) uses the same materials as early thick
> LP records?

Most definitely..a lot of early LPs from RCA, Columbia and Capitol feel 
identical to the vinyl 78s they were producing at the time.
> 
> There are several "non-breakable" 78rpms which comes up in my mind -
> "MERCO PLASTIC" by Mercury, "METROLITE" by MGM, "SAV-O-FLEX" by Savoy
> (and there should be some others - do you know other examples?)

Websterlite (Remington and related labels) comes to mind..
> all of which are not flexible and rather thick, but which seems to
> be different from good old shellac.
> 
>   http://microgroove.jp/archives/2007/07/metrolite_merco_plastic_non_breakable_78rpm.html
> 
> --
>  MATSUBAYASHI, 'Shaolin' Kohji                  [log in to unmask]
>                                                  http://microgroove.jp/
> 

I have even run across a Canadian RCA green label (early 50s) which claims to 
be unbreakable but is pressed on regular shellac..I won't give that one the 
thumbnail test though. Most of the time you can tell by feel, weight, tapping 
the edge etc. There are early Mercury LPs that weigh a ton and early Mercury 
LPs that are lighter than a 45. There are late 40s Mercury 78s that are pressed 
on very quiet material but aren't claimed to be unbreakable, and definitely 
aren't, but they may have a certain amount of vinyl in the mix.

dl