Abstract: In the production of records, a mother is formed from a metal master having a nickel core and a silver coating. To produce the mother, the silver coating is removed from the nickel core and the nickel is passivated by treating the metal master with an aqueous solution containing ammonium persulphate. The same aqueous solution can be used for passivating the mother before the mother is electroplated to form a stamper.

Abstract: A stamper for producing replicas of a video disc master formed of a glass substrate containing surface irregularities in the form of an information pattern of raised protrusions is formed by applying a strike coating of a conductive metal such as silver and then electroplating copper and nickel to form a self-supporting negative replica member, termed as "mother," which can be stripped from the surface of the master. The interior of the mother is cleaned and passivated preparatory to use as a mandrel in the electroforming of a positive replica submaster. The submaster may function as a stamper or be utilized after passivation as a mandrel in the electroforming of a submother from which a stamper or a plurality of stampers are formed.

Abstract: A phonograph record groove eccentricity tester senses the eccentricity of the circular groove at the inner side of the spiral groove, by means of a groove engaging stylus on a pivoted arm operating a sensor that produces an output signal a peak value of which is displayed.

Abstract: Control circuitry for record pressing equipment is provided, and is characterized by ease of shifting between automatic and manual operational modes, and at any stage, as well as by simplicity and ease of operation. The flow control of cooling a heating fluid for the die means is integrated with the control circuitry.

Abstract: A video disc master of glass, having a metal surface with microscopic apertures therein representing information, is coated with a commercial photosensitive resist, the sensitivity of which has been enhanced. The resist is uniformly exposed through the glass disc. The unexposed resist is removed using conventional developers to which a surfectant is added. The resulting disc has surface irregularities of predetermined height which can be alternatively used to product "stampers" for embossing replicas or to produce a mold for casting replicas.

Abstract: An assembly attachable to upper and lower bases of a phonograph record pressing die includes:A. upper and lower die frames, the upper die frame attachable to the upper base, and the lower die frame attachable to the lower die base, andB. upper and lower die faces, the upper die face attached to the upper frame, and the lower die face attached to the lower frame, the upper die face directly overlying the lower die face to press a phonograph record therebetween,C. there being a first set of fluid passing grooves formed in at least one of the upper frame and upper face and exposed to the other thereof, and another set of heat transfer fluid grooves formed in at least one of the lower frame and lower face and exposed to the other thereof.This is a continuation of application Ser. No. 469,387, filed May 13, 1974, now abandoned.