| how vinyl is produced [making the record] |
Are you sitting comfortably...
 t all starts with the disc recorder or "lathe"
as it is often referred to, an amazing piece of equipment designed
with a slowly rotating feed screw mechanism and carriage to move a
cutting head across the radius of the disc. The accurately shaped
cutting stylus, mounted in the head, cuts a precise spiral groove
across a flat lacquer coated aluminum disc (acetate) spinning at an
exact speed of 33-1/3, 45, or in the old days, 78.26 revolutions per
minute, the standard phonograph operating speeds.
 ext see's the cutting head installed on the lathe,
this is simply a phonograph pickup in reverse, that is, feed audio
in and get mechanical motion out. Other than its greater size, the
specially shaped cutting stylus, and the feed screw mechanism which
moves the head across the record to make the spiral groove, the
internal workings are very similar. The recording stylus is probably
the most important component of the recording process, and was
probably first used by Edison in 1877.
 iamond is not a good material for a cutting stylus,
but is excellent as a reproducing stylus. Home cutting styli were
commonly made of a steel alloy because it was inexpensive to
manufacture but most cutting styli for professional use are made of
corundum, better known as sapphire which will outlast a diamond and
produce superior recordings. Since those early recordings on wax,
recording blanks have been called by various names including
instantaneous discs, lacquers, acetates, soft-cuts and others. The
most accurate is probably "lacquer" because of the fact
that they are lacquer coated with a compound of cellulose nitrate,
and acetate had little to do with it, although it has become a
common name for a lacquer coated disc, and many professionals still
use the term "acetate".
 he phrase "waxing," still persists to day
even though the old solid block of wax were in use until not long
before World War II. Before there was no magnetic tape and the
recordings had to be cut originally on huge thick blocks of warmed,
essentially beeswax. The final product before "processing"
became a single lacquered disk onto which the actual recording
grooves were cut. different grades of "acetates" were
offered by the manufacturers, distinguished by the evenness of
coating and thickness of the metal itself. Simply explained, all the
discs of a given grade started through the manufacturing process the
same way, but subsequent inspection determined the quality level
that the disk met before it was shipped out for use. Before setting
off on its spiral course, everything must be pre-set and
double-checked, from the visual selection and flatness of the disc
blank, to the condition of the sapphire cutting stylus, chip suction
and all the audio connections and settings. An appropriate size
recording disc blank is chosen... usually 14" diameter for a 12"
final disc size. Once it's underway a cutting stylus cannot be
stopped without ruining the disk! A silent groove test cut is made,
outside the diameter of the finished disc. This is examined under
the microscope to check for correct groove size, and sometimes
played back to ensure that the noise level is appropriately low.
Sometimes discs are rejected at this stage, or even a cutting stylus
might be changed, before things are ready to begin the actual
recording.
 t this point the vacuum pump is started, tape players
are cued to the beginning of the recording, the cutting turntable
set rolling and now the stylus is carefully lowered to the record
surface. First, the fast beginning lead-in spiral is cut, the tape
playback is started a turn or two after the spiral has ceased and
the audio feed to the disc recorder is enabled. Depth of cut is
periodically checked through the microscope, and of course the
volume levels must be watched even though automatic variable pitch
will protect against most instances of overcutting to adjacent
grooves. The running time must be checked at the 1/4, 1/2 and 3/4
way through, to ensure that the disc reaches the desired end point
necessary for standardization of the finished product. At the end of
the record, after about two blank revolutions, the final spiral
lead-out groove is made by speeding up the lead screw of the cutting
lathe, either automatically or manually, followed by a lock groove.
n earlier times, an eccentric lock groove was added on
a special machine designed for this purpose. The master is now done
and is visually examined very closely for flaws... once made the
master is never played. for moving, the masters are bolted by their
center holes into a complicated box of separations that keep the
actual surfaces from touching, the lacquer is extremely delicate and
easily scratched.
here are only minor differences between records, other than
the most obvious of size and speed, from 7" 45 rpm through to
the 12" 33 rpm. The greatest differences, however, are found in
the groove sizes. Coarse groove 16" radio transcriptions used a
slightly narrower and more closely packed groove than the average 78
"standard", but it is played at 33 rpm. The groove used
for LP's and 45's is smaller still, and much more closely packed.
The problems of groove accuracy with LP's are greater than with the
old larger groove, and for a while after the first LP's in 1948 it
was reported throughout the industry that small groove cutting was
all but impossible. After months of experimenting the cutting of
small grooves became less hassle and no more trouble in this area
than the wider groove process. With minor adjustments to stylus size
and depth of cut any record type could be cut on the same equipment.
Producing a metal press that will actually mold records from shellac
or vinyl is a multiple plating process.
epositing metal upon metal by means of an electric
current that transfers metal through a plating solution directly to
the actual surface being plated. At this point record making is
surrounded by tanks. Rows and rows of containers filled with multi
coloured liquids, some steaming, some sloshing about, as objects are
swished through the depths. To make an actual metal impression the
lacquer must either flow on the metal and let it harden or plate it
on cold. The first process obviously being impossible (lacquer is a
soft, highly inflammable plastic!), some form of plating is the only
answer. But how do you plate metal onto a non-metal? A number of
methods have been used. The oldest, when master records were cut
into wax blocks, was to apply an extremely thin coating of graphite,
a form of carbon that we know as pencil lead, which conducts
electricity. To this coating, thin enough not to disturb the record
groove shape unduly, one could actually plate metal, which would
take on the shape of the record grooves. When enough metal had been
backed up on the plating, it was an easy matter to strip it from the
wax and the graphite, leaving a mold of metal. Three ways are used
to get the first microscopic layer of metal onto the lacquer. Silver
spray is the newest and trickiest and also the silver pan bath is
still used, similar in its chemistry; it takes longer, and is not as
accurate . Lacquers are treated in a different way, to give metal
coatings at first only a molecule or so thick.
he most dazzling to watch involves silver nitrate and
a simple spray gun. The lacquer surface is "sensitized" by
being dipped into a solution of stannous chloride which is washed
off in a water spray, leaving a very thin coating. Silver nitrate
solution is sprayed at the disk and the black becomes a mirror of
silver in seconds. Silver has been deposited in an extremely thin
layer by chemical (replacement) action, the stannous chloride acting
as a catalyst to promote the process. The newly silvered disk is
washed and moves on to its next treatment. The next objective is to
build up a solid metal backing on the thin silver coat. This may be
confusing, since this "backing" is actually being
deposited on the front of the original disk. Remember, that we are
making a negative mold, its surface now of silver, in direct contact
with the lacquer surface and facing away from us as we look at the
record. We are really looking at the silver from the rear, and we
are about to add more metal to that rear in order to stiffen it. The
original record will eventually be stripped away, leaving the other
side of the silver, the facing-down side, as the mold. The beginning
of the build-up of the metal backing support, a layer of very
fine-grained and delicate copper or sometimes nickel, is laid down
slowly on the silver surface just produced. It's fine-grained in
order so not to disturb the tiny groove patterns and to hold them
accurately in place.
fter this, a more coarse grained metal can be piled
on, although in some plants, another layer of fine grained "pre-plating"
is added first. The coarse coating is desirably much faster, since
at the slow fine-grain pre plating speed, it may take weeks to build
up a strong enough layer of metal. One company used special rotating
disk anodes that swish around close to the surface of the metal
record and do the plating job to required thickness in a few hours.
Other much slower systems use the usual immersion tanks with moving
arms to swish the contents about. Enough metal is put on the back of
the silver surface to support it rigidly. and with a quick blow of a
special hammer and with a shaking of the inserting tool, the entire
silver-copper mold breaks free from the lacquer, and we have a
negative in metal, the back side or down-surface of the silver a
mirror-image the original grooves. The lacquer is usually damaged in
this separating process and cannot be used again; so the new metal
negative, or "matrix", is now the only form in which the
grooves exist. Being a negative, the grooves become sharp ridges
with flat valleys between. This metal negative or "matrix"
can now be used to stamp out actual records! Since it is now the
only existing copy of the original lacquer disc, in most cases it is
used to produce a "mother", a positive metal record that
can actually be played for testing purposes. Playing is not this
mother's destined role and instead, the mother is submitted to
another plating operation much like the first, ending in another
metal negative which is the desired "stamper". Since the
mother, unlike the fragile lacquer original, is made of metal, it
can be re-plated many times over, producing negative after negative
in metal, all identical with the first.
 e now have a source of negative offspring stampers,
each of which can press out as many as a thousand or so actual
finished records. Multiple mothers can be made from the original
metal matrix so multiple identical mothers can be sent to other
pressing plants or countries for their production requirements, and
thus huge quantities of records can be produced in a very short time
if need be, all with exactly the same quality level of the release
pressings in the originating country or plant. The first step in
preparing for the creation of the mother is to remove the silver
that now contains the direct groove Impression.. Removing the silver
coating is necessary because it would quickly oxidize and corrode in
the air. Fortunately it is a molecule-thin coating, and the
underlying harder metal has virtually the same sharp image as the
original. A swish or two of chromic acid takes the silver away
faster than it was deposited by spray in the first place. With the
silver off but the groove image still "metalized" in the
negative matrix, the whole plating process is repeated to re-create
a new image. Before plating, a separating solution is applied to the
surface, so that, though metal will plate on metal, it can be
stripped off later on, otherwise the entire thing would become a
useless solid metal block. Next, a hard but ultra-thin chrome
surface must be plated on and next the hole in the middle, plus the
stamper's rear side, which must be shaved to the right thickness to
fit the press and the outside edge which must be trimmed to size.
The rear surface is machined away in a lathe operation where a
precision gouge scrapes a spiral track from the outside of the back,
right to the inside, shaving off all the irregularities, leaving a
mirror-bright flat backside. The edges trimmed, the stamper then
goes to the centering machine. As soon as the master has its hole,
it loses it. Another punch knocks out a larger area, usually a
couple of inches in circumference from the middle to fit the center
of the press. But the disk's position is exactly determined by the
small hole, and so the essential information is preserved, the final
hole in the record to be made in the actual pressing according to
it.
fter the previous steps that occur between the
original recording and the final metal negative stamper disk comes
the final operation of making of the actual record. The basic press
structure is precisely what is needed for record making... two
similar molds, both heated, mounted face to face with a hinge at the
rear so that the machine opens up facing you. Enlarge these two
molds to record size; to hold two record stamper disks, one below
and one above (fastened in by their centers and around the edges),
and you have the beginnings of a record press behind each stamper
comes a sudden heat, using super-heated steam at three hundred
degrees, then quick cooling by cold water, all of which must be
controlled by the opening and shutting of appropriate valves - and
automatically, since no human operator could maintain the exact
desired cycle of hot and cold that produces the perfect record. The
easiest record to make and the most common is the solid disk, of a
single material all the way through, though the more complex
records, such as Columbia's old laminated disk, go through the same
presses. Record and label are bonded together in the pressing. The
operator of a pressing machine has beside him a "hot tray"
on which is placed a dozen or so rectangular blocks of material,
(shellac or vinyl) about half the area and two or three times the
thickness of the final record. The biscuits are softened up on the
hot plate until they are of the consistency of a soggy piece of
fried mush, just about movable in one piece, and no more. With the
press open, first a label, then a biscuit, then another label is
placed in the press, and the top lowered. The automatic system then
takes over unobtrusively; steam heats and flows the plastic material
into every tiny groove; at the predetermined moment it is replaced
by water, and the record is instantly hardened. The record is lifted
out, and the next one is ready to go in.
fter coming out of the hot press the newly made record
has its ragged edge neatly trimmed by a circular cutting device and
then passed on for inspection. Records are rejected by visual
inspection and by actual playing checks. A significant quantity are
rejected - large bins of rejects, returns and cut-outs wait to be
fed to the elaborate machinery that reduces these masses of
unsatisfactory disks to chunks, and then to powder for recycling
into more records. Visual inspection is done by workers who look
closely at every disk that comes to them on conveyer belts, sorting
out the rejects. The supplementary playing-out-loud of a sample
record every so often catches most faults that may have developed in
a stamper before it has pressed too many bad discs.
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