Overview
ISO 3262-14:2023 - Extenders - Specifications and methods of test - Part 14: Cristobalite defines requirements and test methods for cristobalite used as an extender in coatings, ceramics and related materials. It specifies essential composition and purity limits, sampling rules and laboratory procedures (including a gravimetric silica determination) to ensure product consistency and conformity.
Key topics and requirements
- Scope: Requirements and corresponding methods of test for cristobalite.
- Definition: Cristobalite is a low‑temperature form of crystalline silicon dioxide (SiO2) with a theoretical density of 2.35 g·cm‑3.
- Essential requirements (Table 1):
- Cristobalite content, min. 60% - determined by X‑ray diffraction (XRD) or by agreement between parties.
- Silica content, min. 98% - method specified in Clause 6 (gravimetric procedure using sulfuric and hydrofluoric acids).
- Matter volatile at 105 °C, max. 0.2% (ISO 787‑2).
- Loss on ignition, matter soluble in water, pH - specified limits with referenced ISO test methods.
- Conditional requirements (Table 2) (to be agreed between supplier and purchaser):
- Sampling: Representative sampling in accordance with ISO 15528.
- Silica determination: Clause 6 details reagents (including sulfuric and hydrofluoric acid), apparatus (platinum dish, muffle furnace, precise balance) and a stepwise gravimetric procedure with calculation instructions.
Note: ISO 3262‑14:2023 modernizes the previous edition (2000), permits alternative agreed methods for cristobalite determination (beyond XRD) and updates particle size testing to ISO 8130‑13.
Practical applications and users
- Who uses this standard:
- Raw material manufacturers of cristobalite and mineral extenders
- Quality control and analytical laboratories in pigments, coatings, ceramics and plastics industries
- Procurement and regulatory teams specifying extender properties for formulations
- Test laboratories certifying compliance for supply chains
- Why it matters:
- Ensures consistent purity (SiO2) and cristobalite content for predictable performance in paints, powders, ceramics and sealants
- Provides harmonized test methods for comparative quality assessment and contractual specifications
- Supports safety and performance claims by defining standard reporting requirements
Related standards
- ISO 3262‑1 (general test methods for extenders)
- ISO 8130‑13 (particle size analysis by laser diffraction)
- ISO 787 series (general methods for pigments and extenders)
- ISO 15528 (sampling)
Keywords: ISO 3262-14:2023, cristobalite, extenders specifications, methods of test, silica content, X-ray diffraction, ISO 8130-13, ISO 15528, pigment testing, laboratory procedures.
