Abstract: Process for producing a sound recording cutting base, which includes precipitating a cuttable copper layer on a substrate from an electroplating bath, the copper layer having an initial grain size and having recrystallizing characteristics as a result of the bath's composition, convection and current density, characterized in that in order to extend recrystallization time, substances are added to the bath which, by their incorporation in the copper layer, stabilize the latter in such a manner that recrystallization is prevented or delayed, the substances including leveling agents added in effective amounts to prevent formation of layer-grain crystals of copper having a grain size which substantially exceeds the initial grain-size.

Abstract: A disc-shaped information carrier produced by thermoplastic deformation comprising a pressed mass including a co-polymer of vinyl chloride having additives incorporated therein. The carrier has hygroscopic properties and relief-like surface portions which are sufficiently yielding to permit pressure scanning.

Abstract: Process for manufacturing a record carrier having a cuttable copper layer, wherein a copper layer is precipitated onto a substrate in an electrochemical bath and a desired Vickers hardness in the precipitated copper layer is obtained by controlling the concentration of brightener additives. The copper layer is precipitated in a recrystallizable phase, and the recording is cut while the copper layer is in its recrystallizable phase.

Abstract: In an apparatus for forming a groove which is modulated to present an information track in a signal record carrier having a copper surface portion by cutting such groove into the copper surface portion by means of a cutting stylus, the stylus is formed to present, during cutting, a rake angle of between 10.degree. and 20.degree., and the copper constituting the surface portion into which the groove is cut has a Vickers hardness of between 110 and 300, and preferably between 120-220.

Abstract: A rigid polyvinyl chloride foil with modified impact resistance and free from plasticizer especially suitable for the manufacture of audio-visual information carriers with stamped spiral grooves from which the information is played back by pressure scanning. The foil is characterized by a special combination of properties such as flow, reduction in length, toughness, surface resistance, elasticity, peak-to-valley height and surface deposit.

Abstract: A grinding foil which is to be used for grinding a record cutting or playback stylus is manufactured by providing a surface layer of a plastic foil with indentations for accommodating a grinding agent in granular form, filling the indentations with such grinding agent, and thermoplastically deforming the surface layer to smooth the foil surface and to bond the grinding agent into the surface layer.