ISO 3642:1983

Overview

ISO 3642:1983 specifies dimensional and practical requirements for cemented or welded splices on 8 mm Type S motion‑picture film intended for projection. Developed by ISO/TC 36 (Cinematography), this International Standard defines how splices must be made and aligned to ensure reliable projector operation, minimize optical disturbance, and protect perforations and magnetic sound stripes.

Key topics and requirements

• Scope: Applies to 8 mm Type S film primarily intended for projector use and covers both adhesive (cemented) and welded splices.
• Splice dimensions: The standard fixes the geometry and maximum film width at the splice (film width at the splice shall not exceed 8.02 mm (0.316 in)). Detailed dimensioning for splice elements is provided in the standard figures and tables.
• Edge preparation: If film ends have been widened during scraping, the extra width must be removed before splicing to meet dimensional limits.
• Perforation protection: Cutting into or including a perforation in the splice is explicitly prevented-splices must avoid damaging or misaligning perforations.
• Alignment tolerances: Spliced halves must be closely aligned; the standard limits offset and specifies alignment allowances (referenced as dimension G). One specific tolerance cited is that when one film portion is placed against a straight edge the other portion must not deviate more than 0.22 mm (0.009 in) over 152 mm (6 in).
• Splice orientation: Bevelled splices are recommended and a preferred orientation is shown to minimize optical disturbance. For magnetically striped films, the overlap orientation must ensure the trailing image drops onto the sound head rather than bumps into it.
• Optional splice forms: The standard temporarily recognizes an optional symmetrical overlap method (with specified dimensional limits) but anticipates phasing this out.

Applications and users

• Film manufacturers and splicing equipment designers use ISO 3642 to design splicing processes and tooling for 8 mm Type S film.
• Projectionists, post‑production shops, film archivists, and cartridge manufacturers follow the standard to produce reliable splices that avoid projector jams, image artifacts, and sound-head interference.
• Quality assurance and inspection teams use the dimensional tolerances to verify splice conformity and to prevent damage to perforations and magnetic tracks.

Related information

• Developed by ISO/TC 36 (Cinematography). ISO 3642:1983 is the second edition (1983) updating earlier guidance on 8 mm splicing practices.
• For implementation, consult the full ISO 3642:1983 document for exact figures, tables and all dimensional values.

Keywords: ISO 3642:1983, 8 mm Type S, cemented splices, welded splices, motion‑picture film, splice dimensions, film splicing, magnetic stripe splicing, bevelled splices.