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The idea of recording information on a flat carrier using a spiral track
suggested by Emil Berliner as early as 1888 turned out so fruitful (due to
compactness and simplicity of manufacturing of records) that it is being used
even now in modern digital equipment (CD-Audio, CD-ROM, DVD, etc.) Having
as predecessor the Edison's wax cylinder, for which possibility of home recording
was envisaged, Berliner's shellac plate did not have such a possibility. Since
early 1960's home tape-recorders became to be widely used in this country,
which, eliminating that drawback, nevertheless, never attained the level necessary
for rendering the quality of sounding of the best gramophone disks. A digital
audio disk which appeared in 1982, by the existing standard also could not
surpass the velvety sound of the best mechanical records.
It was the time of gramophones with mechanical (spring) disk drive an huge bell-shaped trumpets, which magnified weak vibrations of a steel needle gliding on a disk. People hearing an old gramophone for the first time are usually surprised by the loud sound it produces. The megaphone had another important function - that of cutting off high-frequency noises and cracking of the disk. The magic of a gramophone playing even nowadays finds its admirers among the listeners. But indeed, the disks themselves greatly "suffer" from such exotic pleasures - the steel pick-up arm weighing some tens of grams causes marked damage to the disk after every playing.
Berliner's gramophone disks were 7 inches in diameter, played at a speed of 30 rpm and had a duration of 2 minutes. As with the phonograph, the years immediately following its inception were filled with experimentation and development. A variety of materials and formats were tried: the initial disks were vulcanite rubber, replaced in 1897 with shellac; a 10-inch format with 4 minute playing time replaced the 7 inch format; double-sided disks were developed; and in 1925, with the advent of electrical recording, the speed was standardised to 78 rpm. Prior to this various recording speeds had been used, and players had adjustable speed. Shortly after the first electrically recorded disks went on sale in 1925, a 16-inch acetate-coated shellac disk format with a speed of 33 1/3 rpm was used to synchronise sound to film.
As with cylinders, successful playback of gramophone records requires some specialist knowledge. The sound quality will improve with cleaning the disks and having the correct kind of playback equipment. This will also help to avoid damaging the disks or degrading them further. It is vital that cleaning or repairing disks should only be attempted with appropriate knowledge and equipment.
As with the phonograph, the gramophone will need to be recorded acoustically.
This would be best achieved in a recording studio with appropriate space and
equipment.
In those days disks were produced in two sizes - "grand" (25 cm diameter) with 3 min sounding each side, and "giant" (30 cm - 4 min respectively). For issuing of larger musical pieces (symphonies, operas) plates were combined in sets of some tens of disks.
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Shellac is an animal product. The basic material comes from the Coccus lacca, a scale insect that feeds on certain trees in India and southern Asia. After feeding, the insect produces through its pores a gummy substance which hardens into a protective covering called lac. This lac is collected and then it is crushed, washed and dried. After further treatment, it is skillfully drawn into thin sheets of finished shellac.
Wax" and "shellac" are terms we still associate in popular
language with phonograph records. But not only has wax vanished as a medium
for the actual cutting of records; shellac, too, is almost gone in favor of
the new synthetic plastic products.
For that matter, no record was ever made of pure shellac. The old-stlye 78rpm
"shellac" record was made of a molding material that we now call
a thermoplastic ("melts with heat"), in which shellac was greatly
extended by assorted neutral filler materials, among them the carbon black
which gives the black look to most records. Formulas for record material were
and still are highly controversial and highly variable-quiet surface, hardness,
resistance to breakage, and other features being more or less at odds with
each other. Whatever a record material is compounded of, it must be both hard
and smooth in the cold state, and capable of melting or softening to the proper
degree with heat.
Pure shellac would never do. It would be as brittle as so much thin glass.
Yes, record shellac is indeed the same material as the shellac we find in
the familiar varnish. Shellac-or "lac," its more correct name -
is a natural resin, not unlike the gummy substance found hereabouts on fir
and pine trees. Its source, however, is the Far East, where the female of
a small bug that infests certain trees of sorts unknown in the West, coats
itself for protection with the gummy stuff. Ground-up insects constitute a
goo part of the first shellac product, but various stages of purification
are represented by our orange and white shellacs, which are no more than simple
alcohol solutions of lac. This same substance serves as a binder for the assorted
ground-up an powdered fillers that have made up various phonograph record
materials these many years, the percentage varying according to the formula.
An interesting economic situation has arisen due to the geographical location
of the lac-producing bug and its special tree largely within what was the
British Empire before Indian independence. Britain controlled the world supply
of lac, and all phonograph records made outside the Empire depended British
exports. It is no coincidence, then, that English shellac records have long
been known as the finest made. Whether more shellac was used than in other
formulae is a question; better grades of lac (which, being a natural product,
cannot be absolutely standardized to one grade) are more likely the answer,
since the optimum percentage is not very high. Much of a shellac records quality
was also due to the degree of uniformity and fineness of grain of the neutral
filler or extender that was bound together by the lac.
Vinylite and the Shellac-less Shellac
Today, though millions of so-called "shellac" records are still
to be found in the stores in this country, a large number of them contain
no natural shellac at all! Instead, the binding material - mind you, this
in what seems to be the old-fashioned "breakable" record - is that
modern wonder, vinylite, a synthetic resin plastic made in the United States
by the company that developed the first important thermosetting plastic, bakelite,
almost half a century ago. Now the British must buy vinylite from the United
States. The present-day American "shellac" record is a part-vinylite
disk, the extender, including the traditional ultra-fine powder, carbon black,
being much as it always was, the binding material vinylite instead of lac.
The new plastic "unbreakable" records are also vinylite-made. Unlike
natural lac, this new plastic is flexible, yet strong and hard enough to be
used pure as a material for record making. Pure vinylite is not cheap, and,
strangely enough, a certain amount of cheap extender or fill mixed with the
pure product produces a record claimed to be even better than one made with
vinylite alone. Just how far the addition of other material should be carried
for best results and what materials should be used (discarded records ground
into powder, for instance) are matters for complex economic calculation. The
majority of top-quality LP records, shiny black in color, long-wearing, flexible,
are made with a large percentage of vinylite, but significantly less than
one hundred per cent. Many fine records are made of the pure product, dyed
red for looks, as are many radio transcriptions - not a little of the appeal
being in its attractive appearance, its window-clear transparency.
But the simple fact is that today we are buying records that vary from the pure vinylite type, always transparent often colored, through dozens of formulae containing less and less plastic, more and more of the various extenders, until we reach the shellac-less "shellac" record of current popular standard-speed hits and a few remaining classical albums. Since that record is easily comparable to the best of the earlier true shellac disks, it is clear that in this new synthetic plastic we have a material of enormous economic flexibility, adaptable to all sorts of technical and economic requirements in the record field. But let me emphasize strongly that the percentage of vinylite in a record is not the final measure of its value to you. The actual materials used to extend the pure plastic are of very great importance, as is the uniform fineness of grain of those materials. As I've already suggested, a small addition of carefully chosen materials, including the ultra-fine carbon black, actually improves the basic vinylite's properties for record making, and that is why most high quality plastic records are opaque black. Beyond this, while sound quality and/or wearing quality may decrease, the variations are enormous. Each brand must be judged for itself on these bases, and of course, in relation to the price charged and the value of the record's sound. I know of at least one expensive brand of small-company records that uses a material with very decidedly sub-standard wear properties, though the associated hiss when the records are new is barely audible.
The Waffle-Iron Press
After the half dozen or so processing steps that occur between the original
recording and the final metal negative stamper disk comes the final operation,
the making of the actual record.
The pressing process is surprisingly simple in operation. The waffle maker
comes to mind, and indeed the pressing machine's working parts are not so
very much larger than a good, solid waffle iron, though the accompanying complications
are something else again.
Let's take the home waffle maker as a beginning and do a mental conversion job on it. The basic 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; provide, instead of the waffle pattern, means 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. Waffles cook by electric heat; here we need a major substitution in the form of an elaborate channel system behind each stamper to allow first 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. With this we approach the complete, if hypothetical, conversion of waffle iron to record maker.
The simplest record to make and the most common is the solid disk, of one homogeneous 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, precisely like a standard hamburger hot plate in a quick lunch, on which he places a dozen or so "biscuits" - rectangular blocks of material, (shellac or vinylite) about half the area and two or three times the thickness of the final record. The biscuits soften 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 like a waffle iron, he deftly makes a sandwich, first a label, then a biscuit, then another label, and lowers the top, waffle-wise. 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. As in a good waffle maker, no sticking occurs. Butter or equivalent is unnecessary. The record is lifted out, and the next one is ready to go in.
Incidentally, the occasional reversal of labels on records can easily be understood, since the operator of a pressing machine must put the labels and the biscuit into the press by hand. Nothing is easier than to reach for the wrong pile first, or to put the right pile in the wrong spot in the first place. My wonder in watching these operations was aroused by the positively staggering opportunities confusion that were present - what with dozens, hundreds of piles of labels, biscuits of various sorts, unattached stampers, loaded presses, all of a kind looking more or less alike, and easily interchangeable. Yet in almost every case the right pair of stampers connects with the proper piles of labels and the correct biscuits to produce an acceptable record that reproduces the music it says it will. Drastic mistakes are altogether rare.
Inspection
After coming out of the hot press the newly made record has its ragged edge
neatly trimmed by a circular cutting device (something like a revolving can
opener) and is then passed on for inspection with hundreds of its mates.
If you think that perhaps record companies are less careful than they should
be, witness the inspection process for yourself. I took notes on the percentage
of records rejected by visual inspection and by actually playing checks, but
I won't burden you with these figures. It's enough to say that I am sure I
saw almost as many rejected disks as accepted ones - huge bins of rejects
- and I also saw the elaborate machinery that reduces these masses of unsatisfactory
disks to chunks and then to powder for recyling into more records. Visual
inspection is done by workers who look closely at every disk that comes to
them on conveyer belts, sorting out duds by the binful. 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 disks.
Considering the terrifying possibilities for trouble in this whole mass-production
operation, I'd say we consumers were reasonably well protected.
Multi-speed Operation
Somehow I had always assumed that the new LP and 45 records would have some
special plant unto themselves, utterly removed from the old-fashioned processes
that turned out "shellac" records. I did not realize what a versatile
instrument the record pressing machine is. The required adaptation is all
made quite simply (though no doubt the original research and experiment were
anything but simple) with existing machinery, and thus 33s, 45s, and 78s can
be fabricated cheek-by-jowl all in the same room. The same goes for the "shellac"
and plastic records. Just a matter of a different type of biscuit and a different
pressing cycle, different heats, and different timings. It is to be taken
for granted that microgroove pressing must be more carefully managed than
the old 78 groove; it is, in fact, a somewhat slower process per record. In
terms of playing time, however, the microgroove LP is far faster in the processing
than its equivalent shellac forerunner. Six 78 records that's twelve stampers-to
one LP with two stampers. Important savings all along the line, with appropriate
economies.
Milling and Mixing
The record pressing department is actually a rather quiet and unobtrusive
corner of any large record-making plant. The big noise and the big machinery
and the big (and dirty) storage and conveyer space are parts of the pre-pressing
operations that end in the biscuit. Record material is, except for the infrequent
pure vinylite, a mixture of ingredients. The mixing cannot, unfortunately,
be done merely by pouring materials together or dissolving them conveniently
in a solvent. Grinding is a major operation here - grinding of recycled material,
grinding and mixing of new raw material. Heat, huge furnaces, prodigious rollers
squashing out tons of half-melted ooze, great cutter wheels that slice acres
of hot ooze into convenient rolls or into the ultimate small biscuits, immense
heaps of dusty bags, whole bins of smashed and crushed reject disks (flaunting
irrelevant tatters of familiar labels-one cringes involuntarily at the sight!),
huge hoppers full of black powder, enormous and earth-shaking mills that grind
tons of coarse material down to fine-these elements of a mighty manufacturing
process made up the typical large-scale pre-pressing operation. The modest,
hand-operated individual record presses are utterly dwarfed.
Rejected new records and assorted old ones brought in from outside are a major
raw material. Ground up whole, labels and all, they can be used for the insides
of laminated records. But for other use the paper labels must be removed,
and since this is impractical, the centers are simply stamped out in a big
press, the remaining outside doughnut chopped up and then ground down to feed
back into the endless production lines. Little seems to be lost.
More info to be found on http://www.shellac.org
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