ISO 3617:1994

Overview

ISO 3617:1994 - Photography - Processing chemicals - Specifications for sodium hydroxide is the second edition (1994) International Standard that replaces ISO 3617:1976. It establishes purity criteria and mandatory test methods for photographic‑grade sodium hydroxide (NaOH) used in photographic processing. The standard defines chemical and physical requirements, test procedures, sampling guidance and safety/handling notes to ensure reagent suitability for photographic applications.

Key topics and technical requirements

• Scope and status
  • Specifies requirements for photographic‑grade sodium hydroxide and the tests used to determine purity.
  • All requirements in clause 4 are mandatory; tests are performed on samples “as received.”
• Main purity limits (summary)
  • Assay (as NaOH): 95.0% (m/m) minimum
  • Heavy metals (as Pb): 0.003% (m/m) maximum
  • Iron (Fe): 0.002% (m/m) maximum
  • Halides (as Cl‑): 0.3% (m/m) maximum
  • Carbonate (as Na2CO3): 2.5% (m/m) maximum
  • Calcium + magnesium (as Mg): 0.06% (m/m) maximum
  • Appearance: solution should be clear and free from insoluble matter except for slight flocculence
• Test methods and apparatus
  • Assay by titration (HCl vs NaOH) with phenolphthalein; barium chloride used in carbonate determination.
  • Carbonate determined by continuation of assay titration using methyl orange indicator.
  • Ca/Mg determined by EDTA titration (standard EDTA procedures and buffers).
  • Heavy metals and iron determined per ISO 10349‑5; halides per ISO 10349‑6.
  • Routine laboratory equipment: volumetric flasks, burettes, pipettes, indicators and standard volumetric solutions.
• Safety and handling
  • NaOH is corrosive - avoid contact with eyes/skin; store in labeled, tightly sealed plastic containers; consult MSDS.

Applications

• Quality control of photographic processing chemicals and bulk reagent acceptance testing.
• Supplier specifications for photographic‑grade NaOH to prevent processing defects (staining, fogging, or uneven development).
• Laboratory and manufacturing QA in photographic chemistry, film/print processing labs, and chemical distributors.

Who should use this standard

• Chemical suppliers and manufacturers of photographic reagents
• Quality control and analytical laboratories in photographic and imaging industries
• Procurement, R&D, and process engineers responsible for photographic processing solutions
• Standards committees and technical auditors verifying reagent conformity

Related standards

• ISO 10349 series (Parts 1, 5, 6, 7) - referenced test methods for general procedures, heavy metals, halides and alkalinity/acidity.
• Prepared by ISO/TC 42 (Photography).