Overview
EN ISO 3262-3:2023 - "Extenders - Specifications and methods of test - Part 3: Blanc fixe" is the CEN/ISO standard that specifies requirements and test methods for blanc fixe (precipitated barium sulfate, BaSO4). Published in 2023 and endorsed by CEN, this edition replaces EN ISO 3262-3:1998 and updates analytical methods used for quality control and specification of blanc fixe supplied for industrial use.
Key topics and technical requirements
- Definition: Blanc fixe is a synthetic, precipitated barium sulfate produced by a precipitation process (ISO 3262-3:2023, clause 3.1).
- Essential requirements (typical values from the standard):
- BaSO4 content (minimum): 95% mass fraction - determined by either gravimetric or X-ray fluorescent (XRF) methods (Clauses 6 & 7).
- Residue on 45 µm sieve (maximum): 0.2% (ISO 787-7).
- Matter volatile at 105 °C (maximum): 0.5% (ISO 787-2).
- Loss on ignition (maximum): 3% (ISO 3262-1).
- Matter soluble in water (maximum): 0.5% (ISO 787-3).
- pH of aqueous suspension: 6 to 10 (ISO 787-9).
- Conditional requirements (to be agreed between parties): particle size distribution, colour/lightness, oil absorption, resistivity of aqueous extract.
- Analytical methods and updates:
- Gravimetric BaSO4 determination (simplified in this edition; uses ammonium carbamate in place of sodium carbonate).
- XRF (added as an alternative method for BaSO4 content).
- Sampling per ISO 15528 and use of ISO 3696 water for analysis.
Applications and practical value
- Ensures consistent quality and performance of blanc fixe used as an extender/filler in:
- Paints and coatings, inks and printing, plastics, rubber, adhesives, ceramics and paper.
- Supports quality control, incoming material inspection, specification compliance and supplier contracts.
- Helps formulators control optical properties (whiteness, light scattering), rheology (oil absorption) and chemical stability in finished products.
- Use of standardized test methods (gravimetric, XRF, ISO reference tests) enables comparable results across laboratories and suppliers.
Who should use this standard
- Manufacturers of blanc fixe and other extenders
- QC and analytical laboratories (paint, coatings, plastics)
- Raw material procurement and specification writers
- R&D and formulation teams in coatings, plastics and paper industries
- Regulatory and conformity assessment bodies
Related standards
EN ISO 3262-3:2023 provides the technical and analytical framework needed to specify, test and verify blanc fixe quality reliably for industrial applications.
