dk nkf - Nordisk Konservatorforbund Danmark

The motor was clockwork, and it was more heavy-duty
than other uses of clockwork that was normally made
for discontinuous motion. For this reason the spring
was very strong, and frequently several springs were
connected in series. The thing that set gramophone
motors apart from other clockwork was the centrifugal
governor (or rather, brake) for the speed, which used
friction of leather on a rotating disc rather than the wellknown
air brakes. As the gramophone was a piece of
fine mechanical construction, it was attempted to save
on materials where it might not matter. For instance,
soundboxes were frequently made of nickel plated
zinc alloys (”pot metal”) with the well-known recrystallisation
problems.
Professional recording machines were frequently of
the same basic design as gramophones, only much
more strongly built. The power source was mostly
a weight (e.g. 20 kg) hung in a steel wire wound
around a drum. The need for power to cut a wax at
an outside radius of e.g. 15 cm was appreciable[8].
Home recording
A spin-off from the commercial gramophone
production was the manufacture of stronger
domestic turntables for home recording use. In
this case the record was a one-off, cut directly
onto a disc master in a special lacquer. The lacquer
record had a carrier, most commonly absolutely
flat aluminium, but in times of war glass, zinc, or
even cardboard was used. The manufacturers of the
disc masters were not record companies but came
from the paint and lacquer industry. Each record
made was unique, but they could be played on
most commercial gramophones. In this respect they
adhered to the technical de-facto standards used for
commercial gramophone records. However, in order
not to damage the soft record material, special bent
“trailing” needles were used - they had an angle of
ca. 40 degrees to the horizontal in use. The lacquer
master records later (1945-85) became the standard
master material for commercial record production,
but cut on professional recording lathes.
124
Restoration considerations
concerning components of a sound
recording and reproduction system.
Apart from the considerations required by the
context of the system, the various components and
subassemblies as found in conservation practice also
need a specific, if brief, mention. All restoration or
preservation activities should be controlled by the
basic consideration: what is the goal? Repair of
function or repair of appearance? Old new stock or
replica original parts (or even replacements in better
materials?)[12].
The components encountered in practice are
primarily 1) records, and 2) machines to reproduce
them. Records are primarily of 3 kinds:
- “78s” or “shellac records” that will not
tolerate alcohol or other organic solvents but
certainly brief contact with water and anionic
surfactants (however, the label must not be
wetted).[15].
Played with steel needles, bamboo or other fibre
needles, tungsten-tipped needles (historically), sapphire
or diamond tips (very modern, but Pathé used a sapphire
sphere as a permanent tip as early as 1907!)
- “vinyl”, LPs, “singles” which are mainly
made in a PVC alloy, although polystyrene
and alloys with cellulose acetate are known.
Tolerates water, alcohols.
Played with sapphire or diamond stylii in lightweight
pickups.
- ”lacquer records” (avoid the populist term
”acetates”!!), which are thin lacquer layers of
a nitrocellulose lacquer (not flammable in this
form) with castor oil or camphor as plasticiser
and used as masters or one-off records. If the
surface is not crazed it will tolerate water,
but no organic solvent. Aluminium and glass
substrates will permit correct adhesion for a
long time, but zinc substrates shed the lacquer
irreversibly due to oxide formation on the metal
surface.
Played with ”trailing” steel needles (historically) or
sapphire or diamond stylii in lightweight pickups.