History & Development of the Vinyl LP Record

R.G.Bruce Mitchell

The Beginning

Vinyl resins were first identified in 1838 and the first gramophone record was made in 1877, but the two did not come together until the 1930s. Long playing vinyl records were first made in this country in 1949 and put on sale in the UK on 1 June 1950. To the buying public they were a revolution in the quality of sound recording and reproduction, but to the recording industry it was the culmination of an evolutionary process.
The availability of vinyl resins was however only a part, albeit a vital part, of this evolutionary process. instead of tinfoil, and then a solid wax cylinder. Commercial recording began in 1890, but because of the limitations of the cylinder instruments, only two minutes playing time, limited tonal response, and inability to reproduce the original recording, the invention of the disc for recording soon eclipsed the cylinder record business.
In 1887 Emile Berliner applied for a patent for an instrument for recording on a disc. He called it the Gramophone. In the original instrument a disc of heavy plate glass was coated with lampblack and revolved on a turntable in contact with a stylus mounted on a feed screw which created a spiral pattern on the disc with a lateral zigzag movement. This delicate tracing was 'fixed' with varnish and the record was photoengraved in metal. In due course Berliner introduced the process of making a reverse or negative metal matrix for stamping out positive records. In 1889 Berliner licenced a German toy maker who made 5in diameter discs from celluloid or vulcanised rubber and these were on sale in the UK in 1896. In the meantime Berliner had formed The United States Gramophone Company in 1893, and in this country the Gramophone Company was formed in 1898. With the introduction of the instrument for recording on a disc, a means of producing duplicates by clectro- deposition for moulding or stamping out records, improvements in recording quality by the introduction of a mica diaphragm and hem, and fast but not least, in 1897 the introduction of the shellac moulding compounds, the 'industry for human happiness’ had begun. As early as 1900 the Gramophone company was offering a choice of 5000 recordings.

The Shellac Era

Shellac is a natural thermoplastics resin derived from the secretions of the lac beetle. Shellac compounds changed little over a 50 year period. They comprised approximately 15% shellac resin, the remainder being ground slate and carbon black. The abrasive slate filler was essential in order to prevent the needles on the made in 1877 by Thomas Edison, inventor of the phonograph. This instrument comprised a metal cylinder with a spiral groove on the surface and two diaphragm and needle units, one for recording and one for reproduction. The cylinder was mounted on a screw so that by turning a handle it would both revolve and move from left to right. The recording surface was a sheet of tinfoil wrapped around the cylinder. The recording needle, following the spiral groove, would indent a vertically undulating pattern of the sound vibrations picked up by the mouthpiece. The original design was not a commercial success but later cylinder models were made and used n this country for office dictation until the 1940s.
Improvements included wax coated cardboard heavy pick-up heads cutting through the disc.
Inevitably other resins were evaluated and it is interesting that in 1912 Thomas Edison and Dr Leo Baekeland, the inventor of Bakelite and founder of the American Bakelite Corporation, became acquainted and jointly developed a phenolic resin-coated record. It had a core comprising woodflour and china clay, with an asphaltic binder and a coating of phenolic resin varnish. The 10in disc weighed 10oz, was cumbersome to produce and not surprisingly was not a commercial success.
In the meantime the shellac record business continued to develop. In 1914 the lightweight portable Decca Gramophone was first made and during the war years was a success with the armed forces. In 1920 Paul Whiteman's orchestra's recording 'Evergreen' was the first to sell a million discs. Until this time sound reproduction and recording was mechanical. Frequency range and tonal quality was limited. Electrical sound recording provided an improvement in the quality of sound reproduced and was first used for an historic recording of the Armistice Day service on 11 November 1920. The introduction of radio broadcasting in 1922 gave a stimulus for electrically recorded sound and in 1925 electrically recorded discs became available. During the late 1920s and 1930s attempts were made to develop a long playing record disc from shellac compositions and during the 1930s evaluation of the new thermoplastics began.

The Plastics Era

Vinyl polymers were first produced commercially in Germany and in the USA during the 1920s. In June 1933 an American trade journal referred to the use of vinyl resins for the manufacture of phonograph records, but before the vinyl LP was finally developed in the USA in the late 1940s a number of other thermoplastics had been evaluated, with some commercial success. Polyvinyl acetal resins were used in the UK during the Second World War for transcription records for broadcasting. The discs were 16in in diameter and rotated at 33 1/3, rpm. Although not strictly microgroove they enabled a half hour programme to be recorded. The unfilled record compound had good sound reproducing qualities, but poor wear life. Vinyl copolymers were also evaluated for this application. Also in the UK ‘Talking Book’ records were made from a polyvinyl acetal composition. They were 24in in diameter and rotated at 24rpm. In the USA polyvinyl formal resins enjoyed some success in the post war years, for non-breakable 10in 78rpm children’s records. Filled ethyl cellulose 10in and 12in 78rpm were also made. Later on, after the introduction of the LP microgroove, injection moulded 7in, 45rpm, polystyrene discs for children's records had some success in the USA.

The Vinyl LP

Following the introduction of low-cost, lightweight piezoelectric crystal pick-ups, which gave better quality sound reproduction, the opportunity opened for Dr Peter Goldmark of CBS in the USA to begin an objective study to develop a high quality , long play record disc. The study involved the method of recording, the cartridge and the stylus, the amplifier, the turntable drive and last but not least the material of the record and the shape of the groove. The new record material successfully evaluated by the Goldmark team was Union Carbide's Vinylite copolymer of vinyl chloride and vinyl acetate in the ratio of 88:12. This type of polymer has never been bettered and is still being used. The long play, vinyl copolymer record was launched in the USA in June 1948. In the spring of 1949 a rival record company introduced a 7in disc, which rotated at 45rpm and gave the same playing time as a 10in 78rpm shellac disc. As to be expected the battle of the speeds caused an overall drop in demand until records players were available to play 33 1/3, 45, and 78rpm discs.

Developments in the UK

With improved recording techniques, known commercially as 'ffrr' - full frequency range recording-, and experimental work on moulding microgroove records, by 1949 the R&D department of the Decca Record Company had prepared the way for the future LP. They found that although acrylic polymers produced a high quality record the vinyl copolymers were the best material. Unfortunately the Vinylite chloride/acetate copolymers were expensive to import and Decca used vinyl chloride/vinylidene copolymers made in the UK until the Union Carbide patents expired. These vinylidene copolymers, whilst capable of making perfectly good records did not have the flow properties of the vinyl chloride/vinyl acetate copolymers and were difficult to mould. Decca began moulding LPs in 1949 and initially they were all sold in the USA. The British recording industry had always had a leading role through recording rights for classical music, which led to British companies taking a financial interest in American record companies - hence the initial orders from the USA where the demand was well established. Vinyl LPs were launched in the UK on 1 June 1950.
EMI entered the LP record market in October 1952, and the chart shows how growth and then decline has occurred since reliable figures were first available in 1955. A number of other well- known companies also started to produce vinyl LPs in the UK and shellac records were not made in the UK after 1964 The peak demand for vinyl LPs occurred in 1975, when over 91 million were sold. With an average weight of 125g for a 12in disc, estimated UK consumption of record compound peaked at between 12,000 and 14,000 tonnes annually, excluding material used for 45rpm discs.

Method of Manufacture

The formulation of vinyl record material is straightforward; 97% polymer with additives comprising carbon black, heat stabilisers and very small amounts of lubricants and flow promoter. The blending of these ingredients, and the manufacture of a microgroove LP is however a precision moulding process. The first stage was initially a mixing process similar to that used for shellac records. A premix of all the ingredients was charged into a steam heated chamber and the hot dough rolled into a sheet, cut up into biscuits and then cooled. The 'biscuits' could be stored, but were later replaced by granular material. The biscuits, or granules, were softened on a steam heated table and then compacted before being placed in the record press. In later years a more sophisticated process was developed by feeding the premix into an extruder to produce a rod or slug cut to length for direct feeding into the press.
In a microgroove LP the grooves are 0.002 to 0.003in across and a similar depth. There are around 250 grooves to the inch and there can be half a mile of track in a 12in LP. The playback stylus has a tip radius of only 0.001in - usually a sapphire or diamond tip cemented to a metal shank. The walls of the groove have a 900 included angle and a bottom radius of 0.0025in or less. This means that the stylus tool, or stamper, therefore has to be made to a high degree of precision. The stampers fixed in the moulding press are of nickel and made by electrodeposition in a series of processes starting from the original recording on a nitrocellulose coated aluminium disc.
The author is pleased to acknowledge the enthusiastic support of former colleagues, and of past and present employees of raw material manufacturers and record companies in the UK and in the USA. 'I am very grateful to all concerned for their contributions, to this account, and to the 'Industry for Human Happiness'.