From: Patent Tactics, George Brock-Nannestad
Matt Sohn recalled:
> >> I've a pretty good hand at transferring ETs, but the
> >> cracks in the lacquer
> >> make this one a real challenge. Is there any way of
> >> restoring these
> >> grooves? I thought of prying off some of the lacquer in
> >> chunks to glue back
> >> in place, but I'm not sure the grooves would line up even
> >> then.
> I recall talking to someone a long time ago who said he used
> clear nail polish to fill in the cracks. I don't remember
> who it was or how exactly he did it, or what possible damage
> to the disc might result from such a procedure, but I
> thought I'd pass it along..
----- I would not recommend nail polish. While the softening agent is nice
and makes for a tough coat, the solvents are the same as for cellulose
nitrate - because nail polish is mostly cellulose nitrate! This means that
you would eat into the edges of the lacquer layer. This makes for better
bonding but also rounded curves. And you still have to cut a groove to carry
the stylus from where it leaves lacquer to the correct place at the other end
of the gap. And, as I said, nail polish is tough!
I have had good results with waxes (low-melting micro-waxes). BUT, waxes
usually implies heating and applying it in liquid form. On an aluminum base
the heat of solidification will be distributed to other areas, causing
differential heating, and who knows what damage that might cause. On glass it
is safer. Using a solvent for the wax that is not also a solvent for the
cellulose nitrate (paraffin would work for some waxes) would permit
application of the liquid and then wait for the solvent to evaporate. You
need to cut grooves under the microscope to connect correctly, but that is
simple - the worst crack I have come across was 3.5 millimeters (narrowing to
zero over 40 mm, and a ruler to support the scriber was quite sufficient. And
the wax is very easy to cut.
But you have to remember that the shrunken lacquer also has a shrunken time-
base, so it is not just a question of removing the clicks of silence, but of
stretching time, perhaps 5%, perhaps less, of the sound you do obtain.
Again, like Eric said, it takes experience, and whose lacquer record is to