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How records are made

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THE LACQUER DISC

Over the years, since the days of wax, recording blanks have been called by various names including "instantaneous discs", lacquers", "acetates", "soft-cuts" and others. If there is a "proper" name, it 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". Habits are hard to break.

The term "waxing," still persists to this day, even though actual wax is as out of date in disc cutting as the horse and buggy is to the automobile. In the "bad old days" of recording, there was no magnetic tape and the recordings had to be cut originally on huge thick blocks of warmed, essentially beeswax. Modified versions of the old solid block of wax were in use until not long before World War II.

With the acceptance, in the early to mid thirties, of the much more satisfactory lacquer-cutting process, wax went the way of the Dodo bird. Thus, the final product before "processing" became a single lacquered disk onto which the actual recording grooves were cut.

If you are old enough to ever have made an instantaneous recording, those one-of-a-kind records that studios, department stores, vending machines and the like made for you on the spot, you have seen a lacquer disk. It is made of metal (although the very cheap ones had a paper base), usually aluminum, coated with a thin layer of black, smooth, shiny lacquer. For professional master work, the lacquer surface must be perfectly even... just like a black mirror, and as a matter of fact, you can actually see a good reflection of yourself in a lacquer!

Different grades of "blanks" were offered by the manufacturers, distinguished by the evenness of coating and thickness of the metal itself. Simply put, 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 of the plant... a "double face master" being the highest level sold for the highest price. A disc with a blemish on one side, but otherwise master grade would be a "single face master" and sell for less. More blemishes and defects produced lower quality levels that sold for less and less down to the level of the home recording user. Needless to say, for the making of commercial pressed records or radio transcriptions there was only one standard - the best that can be had for the purpose.

THE DISK CUTTER

A high quality professional disc recording lathe system is very impressive, to say the least... accurately controlled to produce grooves that lie precisely even, next to each other, and such that the depth of the groove being cut will remain uniform and exactly as set, throughout the recording.

The mastering engineer controls all aspects of the overhead cutting mechanism, which extends from the outside edge, across the record, to the center pin, like a bridge over water, and from which the recording head with its stylus is lowered to the record surface. The spiraling grooves are cut by moving the head very slowly, across this bridge, usually by a type of screw feed. Think about a home phonograph playing a record, where the arm follows or "tracks" the pre-set grooves in the record. A disc recorder working upon a blank disk, has no such thing to guide it's motion, and so it must be mechanically moved by a special mechanism to cut spiral grooves. Provisions are made to allow speeding up the mechanism to make the faster spirals at the beginning and end of the record, as well as disengaging the feed-screw drive to permit making a "lock" groove at the end of the record. In earlier days, or with less automated professional equipment, the mastering engineer usually did this by turning a small hand operated crank to speed up the spiraling process.

The record grooves are very small, measuring on the order of 2 mils (thousandths of an inch) for microgroove and about 5 mils for coarse groove recordings (transcriptions and 78's). So that the mastering engineer can look at and measure this tiny area, professional disc recording systems come with attached calibrated microscopes, that can be swung over the groove while the record is being cut. Through the microscope a good mastering engineer can quickly determine if the cut is smooth and of the right depth with the grooves far enough apart so as not to interfere with each other. (Sometimes the pattern of one groove, cut too close, may distort the wall of an adjacent groove, giving a strange almost ghostly "echo" that can be heard just before the first sound or after the last sound on some records.)

THE CHIP

The continuous thread of cut material that the stylus throws off as the groove is made is called by a few names... chip, swarf, thread and probably a few others, although "chip" was probably the most common. Most home disc recording enthusiasts ran afoul of this exasperating byproduct. On occasion, it would throw itself nicely to one side and lie flat on the disk in neat rows out of harm's way, but far more often, if not attended to, it would entangle itself on each turn with the chip cut on earlier turns. Catching under the stylus, it quickly builds a rat's nest of tangled material which ruins the cut since, while recording, you cannot lift the stylus away from the record in order to clear it without interrupting the recorded sound and the groove itself. "Chip" accumulates static electricity as it is cut from the groove, and it sticks obstinately to anything and everything in sight, but mostly to the uncut lacquer surface that the cutting head is moving towards! A dry paint brush was usually used to push the chip well out of the way of the advancing cutter head.

Chip is flammable, and can, if a quantity of it is burned, produce a surprising amount of acrid white smoke. Practical jokers working for radio stations were known to take the chip pot from the disc recording room, and set it inside the door of an announce studio just as a long newscast had started, tossing a match in the pot and let it fizzle and sputter producing volumes of smoke to fill the studio to the exasperation of the poor news reader who desperately tried to keep his composure!

The solution to the chip problem for the professional was fairly easy. A small flared pipe mounted near the inside edge of the cutting head was connected to a vacuum system. This drew in the chip, swallowed it whole, and captured it into a large bottle of water for flammability protection. The chip nevertheless can still make agonizing trouble. Many a record master has been spoiled by chip at the last minute when all else was perfect.

 


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