Overview
ISO 1249:1974 specifies requirements and corresponding test methods for zinc chromate pigments - specifically basic zinc potassium chromate (types la and lb) and zinc tetrahydroxychromate (type 2). The standard covers pigment composition, permitted impurities (including a permitted lead content up to 2% PbO in one lead-containing type), sampling and a series of analytical tests. These pigments are intended for use in paints and corrosion‑inhibiting coatings. ISO 1249 replaces ISO Recommendation R 1249‑1970.
Key topics and technical requirements
- Pigment types defined
- Basic zinc potassium chromate (types la and lb - type lb may contain up to 2% PbO)
- Zinc tetrahydroxychromate (type 2)
- Composition and purity limits (selected requirements from the standard)
- Chromate (Cr2O3) content: minimum specified for basic zinc potassium chromates; type 2 has a lower specified range.
- Alkali metal (K2O): maximum content specified.
- Water‑soluble ions: sulphate, chloride and nitrate - maximum 0.1% (m/m) each.
- Matter soluble in water: maximum 0.3% (m/m).
- Matter insoluble in ammoniacal ammonium chloride: specified limits differ by type (e.g., higher allowable for lead‑containing type).
- Residue on 63 μm sieve, volatile matter at 105 °C, and oil absorption: specified limits/tolerances (e.g., oil absorption within ±15% of agreed sample value).
- Analytical/test methods
- Sampling per ISO 842.
- Chemical and physical tests referenced to ISO 787 (General methods of test for pigments) and included titrimetric and gravimetric procedures (e.g., iodometric/sodium thiosulphate titrations for chromate determination, water‑extract analyses for soluble ions).
- Reporting precision
- Results are reported to specified decimal places depending on the test (e.g., one or two decimal places).
Applications
- Formulation and quality control of anticorrosive primers, industrial coatings and metal‑protective paints using zinc chromate pigments.
- Specification and acceptance criteria for pigment suppliers and paint manufacturers.
- Use in corrosion‑inhibiting coatings where chromate pigments are selected for passivation and rust‑inhibiting properties.
Who uses this standard
- Pigment manufacturers and suppliers (product specification and batch control)
- Paint and coatings formulators (raw‑material acceptance)
- Quality control and analytical laboratories (test procedures and reporting)
- Procurement/specification engineers and standards committees in industrial coatings
Related standards
- ISO 787 - General methods of test for pigments (referenced test procedures)
- ISO 842 - Sampling of raw materials for paints and varnishes
- ISO 1249 (1974) replaces ISO Recommendation R 1249‑1970
Keywords: ISO 1249, zinc chromate pigments, basic zinc potassium chromate, zinc tetrahydroxychromate, corrosion‑inhibiting coatings, paint pigments, test methods, ISO 787, ISO 842.