Overview
EN ISO 3262-4:2023 (CEN adoption of ISO 3262-4:2023) specifies the requirements and corresponding test methods for whiting, a natural calcium carbonate (chalk) used as an extender in paints, coatings, plastics and other formulations. This second edition supersedes EN ISO 3262-4:1998 and aligns essential quality criteria, sampling and analytical procedures to ensure consistent material performance.
Key topics and technical requirements
- Material definition: Whiting is defined as natural calcium carbonate derived from chalk, characterized by microcrystalline calcitic crystals and residual shell fragments.
- Essential requirements (Table 1) - examples:
- CaCO3 content: Grade A ≥ 98% mass fraction; Grade B ≥ 95%.
- Matter volatile at 105 °C, loss on ignition (max 46%) and matter soluble in water (max 0.5%).
- pH of aqueous suspension: 8.0 to 9.5.
- Matter insoluble in hydrochloric acid: max 2% (Grade A) and 5% (Grade B); method and calculation are specified.
- Conditional requirements (Table 2) - to be agreed between parties:
- Residue on 45 µm sieve, particle size distribution (instrumental method - now ISO 8130-13 laser diffraction), colour/lightness and resistivity of aqueous extract (ISO 787-14).
- Sampling and test procedures:
- Sampling according to ISO 15528.
- Detailed laboratory method for determination of matter insoluble in HCl (sample ~10 g, approx. 25% HCl, boil 15 min, filter on 0.8 µm membrane, dry at 105 ± 2 °C and weigh; formula provided).
- Normative references include ISO 787 parts, ISO 3262-1, ISO 3696, ISO 8130-13 and ISO 18451-1.
Applications and users
This standard is intended for stakeholders who manufacture, buy, test or regulate extenders and raw materials:
- Paints & coatings manufacturers - to specify filler performance and ensure batch-to-batch consistency.
- Quality control and testing laboratories - for standardized test methods and reporting.
- Raw material suppliers and procurement teams - to define contractual requirements for whiting grades.
- Plastics, paper and adhesive formulators - where calcium carbonate filler properties affect processing and final properties.
- Standards writers and regulatory bodies - for harmonized product definitions and conformity assessment.
Benefits include improved material consistency, reliable performance in formulations, and clearer trade/compliance terms.
Related standards
- ISO 3262-1 - Introduction and general test methods for extenders
- ISO 787 series - General methods of test for pigments and extenders
- ISO 8130-13 - Particle size analysis by laser diffraction
- ISO 15528 - Sampling of paints, varnishes and raw materials
- ISO 18451-1 - Terminology for pigments, dyestuffs and extenders
Keywords: EN ISO 3262-4:2023, whiting, extenders, calcium carbonate, specifications and methods of test, pigments and extenders, particle size, matter insoluble in hydrochloric acid.
