ISO 3942-1976 PDF
Name in English:
St ISO 3942-1976
Name in Russian:
Ст ISO 3942-1976
Original standard ISO 3942-1976 in PDF full version. Additional info + preview on request
Full title and description
ISO 3942:1976 — Photographic grade sodium carbonate, monohydrate — Specification. International standard defining the quality, purity limits and test methods for sodium carbonate monohydrate intended for photographic processing and related photographic chemical uses.
Abstract
This standard specifies chemical and physical requirements and associated test procedures for photographic‑grade sodium carbonate monohydrate (Na2CO3·H2O). It establishes minimum assay (purity) criteria, limits for selected impurities (iron, heavy metals, halides, free alkali, bicarbonate), appearance and form, and simple limit tests used to verify conformity. ISO 3942:1976 has been withdrawn and its requirements were incorporated into a later consolidated standard for photographic sodium carbonate (ISO 424).
General information
- Status: Withdrawn (replaced by ISO 424:1994).
- Publication date: 1976 (first edition published September 1976); withdrawn effective 19 October 1994.
- Publisher: International Organization for Standardization (ISO), prepared by ISO/TC 42 (Photography).
- ICS / categories: 37.040.30 — Photographic chemicals.
- Edition / version: Edition 1 (1976).
- Number of pages: 5 pages (first edition).
Scope
ISO 3942:1976 covers the specification of photographic grade sodium carbonate monohydrate: the required minimum assay (expressed as Na2CO3·H2O), acceptable impurity limits, physical description (white crystalline granules), and the test methods or limit tests to be used for verification. The scope is limited to material intended for photographic processing and related photographic‑chemical applications; it does not cover technical grades for other industrial uses.
Key topics and requirements
- Minimum assay (purity) requirement for sodium carbonate monohydrate (expressed as Na2CO3·H2O) — established as a high‑purity photographic grade (typical requirement: not less than 98.5% by mass in the monohydrate form).
- Limits on trace impurities — examples include strict limits for iron and other heavy‑metal contaminants and limit tests for halides and bicarbonate.
- Limit tests and specified analytical procedures — simple comparative or colorimetric/volumetric tests (for example, a limit test using ammoniacal silver nitrate for halides and specified procedures for determination of assay and iron).
- Physical description and storage/appearance guidance — white crystalline granules; recommendations to avoid contamination and to store in closed containers to preserve photographic quality.
- Conformity criteria — pass/fail limit tests given for routine quality control of photographic chemicals and procurement specifications.
Typical use and users
Primary users were manufacturers of photographic processing chemicals, film and paper processors, procurement/specification engineers in photographic supply, quality control laboratories in photographic chemical production, and conservation/archival professionals specifying high‑purity reagents for photographic restoration and processing.
Related standards
ISO 3942:1976 was withdrawn and its content consolidated into ISO 424 (subsequent edition ISO 424:1994 — Photography — Processing chemicals — Specifications for anhydrous sodium carbonate and sodium carbonate monohydrate). Related test‑method standards from ISO/TC 42 and other photographic chemical series (for example, parts of ISO 10349 on photographic‑grade chemical test methods and standards covering processing waste analysis) provide complementary analytical procedures and handling guidance.
Keywords
ISO 3942, sodium carbonate monohydrate, photographic grade, Na2CO3·H2O, purity specification, assay, impurity limits, iron content, halide test, photographic chemicals, ISO/TC 42.
FAQ
Q: What is this standard?
A: ISO 3942:1976 is an International Standard that specified requirements and test methods for photographic‑grade sodium carbonate in the monohydrate form (Na2CO3·H2O).
Q: What does it cover?
A: It covers purity (assay) requirements, limits for selected impurities (iron, heavy metals, halides, bicarbonate, free alkali), physical description and the limit tests or analytical methods to demonstrate conformity for photographic use.
Q: Who typically uses it?
A: Chemical manufacturers producing photographic reagents, quality control laboratories, photographic processors, procurement/specification staff for photographic supplies, and conservators working with photographic materials.
Q: Is it current or superseded?
A: ISO 3942:1976 has been withdrawn. Its content was incorporated into ISO 424 (the later consolidated standard for photographic sodium carbonate). The withdrawal became effective on 19 October 1994 when ISO 424 (1994) superseded it.
Q: Is it part of a series?
A: It formed part of the body of ISO standards prepared by ISO/TC 42 (Photography) covering photographic‑grade chemicals and test methods; related documents include ISO 424 and various ISO 10349 parts that provide complementary analytical procedures.
Q: What are the key keywords?
A: Sodium carbonate monohydrate, photographic grade, Na2CO3·H2O, purity, assay, impurity limits, iron, halides, photographic chemicals, ISO 3942, ISO 424.