The Manufacturing process

A big thank you goes to Mr L aka George Bettyes who has kindly given me lots of information. He worked as a Disc Mastering Engineer at DECCA Studios from 1957 to 1972

George Bettyes: During the time I was working at the Decca Studios there was only one pressing plant. It was located  on the outskirts of London at a place called New Malden. The address was:

BURLINGTON ROAD

NEW MALDEN

SURREY.

All the masters were cut at the studios at

Broadhurst Gardens

West Hampsteadi

North West London

Every day they were dispatched to the plant at New Malden for processing and pressing. To my knowledge there was never any other Decca pressing plant in the UK.

Master tape

Everything starts from the master tape. A master tape is the ready mixed and produced set of songs that should be on one side of the final record. To be able to get the sound from the tape down to a disc we need a Laquer Disc and a cutting (recording) machine called a Mastering Lathe.

Laquer disc, also called Master disc

This is a thin aluminium plat that has been coated with a thin layer of laquer. The surface has to be absolutely perfect as any damage what so ever may have an impact on the final sound on the record.

Laquer Matrix, Master Laquer

Laquer disc is put into the Mastering Lathe maching. The master tape is plaid and the sound from the tape creates a vibration in the cutting needle that cuts the grooves into the surface of the Laquer disc. The ready cut disc is then called a Laquer Matrix. If the disc is approved in quality control, then it will be called Master Laquer. The matrix number is then added on the approved Master Laquer on the ”dead vax” area, for example XARL-6271-1A.

George Bettyes: "For a long play record a 14 inch disc was used and for a 7inch 45rpm record a 12inch laquer disc was used. This is so that the pitch and depth of cut can be set as there would be no room if the laquer was the same size as the record. The Mastering Engineer would scribe the matrix number and his identity letter on the outer rim of the laquer, so that the factory could identify the laquer before processing. Decca always engraved the matrix number on the dead wax area before processing started."

Metal Master

The Master Laquer is then sprayed with a thin liquide  chloride and silver solution, the thin chloride is a sensitizer that helps the silver stick to the lacquer.  The Master Laquer with the silver coating is then put in a bath of a nickle solution. An electric current is passed through the solution and the nickle particles in the bath are attracted to the surface of the disc. This process will create a rather hard mirror piece of the Master Laquer.

The Master Laquer is then removed form the new metal cover. This new piece is called Metal Master. This disc is a negative one

George Bettyes: "Only one Metal Master could be taken from a laquer master as being very soft it was usually damaged when being separated from the metal master."

Metal mother

The next step is to create a Metal Mother from the Metal Master. This disc is a positive one, meaning that it could be played. The Metal Mother is numbered. This number will be visible at approximately 9 a clock on a Decca vinyl.

George Bettyes: "Several metal mothers were made from the metal master before it deteriated and could not be used anymore.

Stamper

The stamper is then made form the Metal Mother. This is the disc actually used for pressing one piece of a final record. The stamper number was marked in the off groove area at approximately 3 a clok and a letter from the word BUCKINGHAM was used for the numbering system.

George Bettyes: ”A number of stampers can be made from each mother, so that for a large selling record several presses could be set up for the production run. When a stamper is made it has to be carefully centered before punching out the centre hole to ensure that the finished record turns true on its centre. The outside diameter of the stamper is trimmed of excess material to ensure it fits into the press jaws correctly. A stamper could produce about 2000 discs before it had to be replaced.”

Vinyl record

George Bettyes: ”To make the finished record  two stampers are fited into the press,one in the upper fixture ,side one and one in the lower fixture, side two. Labels are then placed in the press and a piece of vinyl is then placed  between the plates. The press jaws were then closed and were heated to soften the vinyl to allow it to flow. Then the jaws were cooled to harden the disc ,the press was then opened and the finished record was then removed from the press ready for inserting in the sleeve.”