Overview
EN ISO 788:2022 (ISO 788:2021) - Ultramarine pigments is a CEN adoption of the ISO standard that specifies requirements and corresponding test methods for artificial ultramarine pigments used in paints, plastics, rubbers and other applications. The standard defines classification, physical and chemical limits, sampling, analytical procedures (including an iodometric method for free sulfur), marking and test report content. It replaces the 1974 edition and tightens key limits while adding element-content restrictions and durability tests.
Key topics and technical requirements
- Scope: Applies to artificial ultramarine pigments for industrial use (paints, plastics, rubbers, etc.).
- Classification:
- Type A - free sulfur ≤ 0.05% (mass fraction)
- Type B - free sulfur ≤ 0.20%
- Basic technical requirements (selected):
- Matter soluble in water (hot extraction): Type A ≤ 1.0%, Type B ≤ 1.5% (ISO 787-3)
- Residue on 63 µm sieve (water method): Type A ≤ 0.1%, Type B ≤ 0.5% (ISO 787-7)
- Matter volatile at 105 °C: ≤ 1.0% (ISO 787-2)
- Density at 23 °C: 2.23 to 2.40 g/cm³ (ISO 787-10)
- Organic colouring matter: negative test (see Clause 11)
- Elemental limits (Table 3, selected values from the standard extract):
- Hg ≤ 1 mg/kg, Cd ≤ 5 mg/kg, Se ≤ 10 mg/kg, As ≤ 10 mg/kg, Cr ≤ 50 mg/kg, Pb ≤ 50 mg/kg
- (Sb limit and full table are specified in the standard.)
- Added and revised test methods:
- Free sulfur determined by an iodometric method
- Tests for resistance to light and resistance to bleeding
- Other sections: Sampling (ISO 15528), marking and labelling, and test report format.
Applications and who uses this standard
- Paint, coatings and inks manufacturers - ensure pigment quality, stability and regulatory compliance.
- Plastics and rubber compounders - verify pigment suitability for processing and durability.
- Quality control and R&D laboratories - perform standardized tests for free sulfur, water-soluble matter, sieve residue, elemental impurities and light/bleed resistance.
- Procurement and compliance teams - specify EN ISO 788:2022 in supplier contracts to meet safety, performance and environmental limits.
Related standards
- ISO 787 series (general pigment test methods: colour, volatile matter, pH, oil absorption, sieve residue, tinting strength, etc.)
- ISO 1248:2006 (iron oxide pigments)
- ISO 3696 (water for analytical use)
- ISO 15528 (sampling)
- EN 14469-4 (bleeding in PVC-P)
Using EN ISO 788:2022 helps manufacturers and labs apply harmonized test methods and element limits for ultramarine pigments, improving product consistency and regulatory adherence.
