Overview
ISO 2495:1995 - Iron blue pigments - Specifications and methods of test defines the composition, physical characteristics and laboratory test methods for iron blue pigments (for example Prussian blue / iron cyanoferrate) used in paints, varnishes and related applications. The second edition (1995) cancels and replaces the 1972 edition and specifies both essential and conditional requirements plus validated analytical procedures for quality assessment.
Key topics and technical requirements
- Composition requirements
- Specifies minimum contents for basic iron (sum of Fe(II) and Fe(III)) and iron cyanoferrate complex, and a minimum total iron (Fe) expressed by mass.
- Physical and appearance criteria
- Defines acceptable form (soft dry powder or readily crushable to the reducible state) and freedom from added colouring matter.
- Essential quality tests
- Volatile matter, matter soluble in water (hot extraction), and acidity/alkalinity of aqueous extract - with maximum limits given.
- Conditional performance characteristics
- Colour (including colour on reduction), relative tinting strength, oil absorption, and dispersion behaviour; some values to be agreed between interested parties.
- Analytical methods
- Two method routes (Method A - referee, and Method B) for determination of basic iron and hexacyanoferrate complex contents using established wet-chemical titrations and redox procedures.
- Referenced general test methods and laboratory practices
- Incorporates/refs ISO 787 parts (general pigment test methods), ISO 842 sampling, ISO 3696 (water for analytical use), and other laboratory glassware and method standards.
- Safety & environmental notes
- Recommends analytical-grade reagents, grade 3 water, and includes a note on removal of mercury from waste solutions (see Annex A for guidance).
Practical applications
- Quality control and acceptance testing of iron blue pigments supplied to the coatings, inks and plastics industries.
- Establishing supplier specifications, contract testing, and dispute resolution (Method A designated as referee).
- Ensuring batch-to-batch consistency for colour, tinting strength, oil absorption and dispersion performance in formulations.
Who should use ISO 2495:1995
- Pigment manufacturers and formulators
- Paint, ink and varnish quality laboratories
- Procurement and specifications engineers
- Test laboratories and regulatory bodies involved in pigment compliance and material verification
Related standards (for laboratory and test context)
- ISO 787 series - General methods of test for pigments and extenders
- ISO 842 - Sampling of raw materials for paints and varnishes
- ISO 3696 - Water for analytical laboratory use
Keywords: ISO 2495, iron blue pigments, Prussian blue, pigment specifications, methods of test, hexacyanoferrate, basic iron content, pigment quality, oil absorption, tinting strength.