----- Original Message ----- 
From: "Tom Fine" <[log in to unmask]>
> Hi Steve:
> Yes, all of what you say is absolutely true! And moreso with LPs because of
smaller grooves
> (although disco singles have the widest/deepest grooves of any LP since the
advent of 0.7 mil
> stylii). Like I said, we were shocked (shocked!) that it worked.
>
> By the way, I'd be reluctant to use real-deal Crazy Glue on shellac. No
chemistry facts to back me
> up, but since shellac seems more fragile and "softer," I'd worry that Crazy
Glue would eat away the
> edge on which it was applied and thus assure the "pie slice" wouldn't fit
correctly. Might be a
> phantom menace ...
>
As near as I could tell, applying "Crazy Glue"(TM?) to shellac compound had
no noticeable solvent, or similar, efffect...in fact, thed problem(s) I
encountered suggested that the surface of a broken 78 is simply too
smooth to allow it, and other adhesives, to "adhee" to the two surfaces
on a longer-term basis. As well, I wasn't thinking of a "pie slice" break,
which only occurs when two cracks happen to cross one another inside the
"circle" defined by an intact phonorecord!

I have no physical explanation for this...but the most common form of
"break" on 78's is called (quite accurately) a "bite"...in which an
arc-bounded piece of the disc breaks off (except for a few records
that literally "break in two" along a straight line...!) Since the
"bite" form of break usually creates a second, non-concentric (what
is the term when two arcs curve in opposite directions...?!) arc
which touches the arc defined by the spiral groove at some point.
This "touch" is, in theory, not of finite length...but, in practice
(and especially when a segment of the break's arc actually follows
the groove path...fairly common...!) does have at least an "effective"
length! This is where they tiny width of the adhesive layer impacts
playability of the repaired phonorecord (I can't even IMAGINE successfully
repairing microgroove discs...which have groove widths of .001" or even
.0007"!)...

I'm wondering if there could be a possibility of using an alcohol-based
glue for shellac 78's. This would work like the old "plastic model glue"
I used to use as a youngster (before folks discovered it could be used
for "sniffing...?!) which actually dissolved the surfaces of the two
plastic parts which you were trying to "adhee," so they could then
harden into what was effectively one single piece of plastic!

I'm about to try glue-repairing a treasured Little Wonder disc (it is
actually Ted Lewis hisownself, playing a 6" version of one of his
Columbia hits...!). The break is to a great extent inside the grooved
portion, so the problem with an outwardly-dislocated tangent-zone
groove shouldn't be involved...!

Steven C. Barr