Overview
ISO 10601:2007 defines specifications and corresponding test methods for natural and manufactured micaceous iron oxide (MIO) pigments supplied in dry form and used primarily in protective coatings for steelwork. The standard focuses on the particle lamellar structure, composition and physical tolerances that influence protective performance in coating films.
Key practical objectives in the standard include:
- Ensuring a high proportion of thin, lamellar particles that form overlapping layers in paint films
- Specifying chemical and physical limits (e.g., Fe2O3 content, volatile matter, water-soluble fraction)
- Providing a reproducible microscope-based method to classify lamellar content
Key Topics
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Scope and classification: MIO pigments are classified by lamellar content into two classes: Class A (>65% lamellar particles) and Class B (50–65% lamellar particles). Pigments with lamellar structure below 50% are not considered micaceous.
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Essential requirements: The standard lists essential characteristics and test methods. Representative requirements given in the document include:
- Minimum iron content expressed as Fe2O3 (determined after drying at 105 °C): minimum 85% (ISO 1248)
- Maximum volatile matter at 105 °C: 0.5% by mass (ISO 787-2)
- Maximum water-soluble matter (hot extraction): 0.5% by mass (ISO 787-3)
- Sieve refusal criteria for particle size distribution (ISO 3549), including defined limits at 63 µm and 105 µm depending on pigment type
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Lamellae evaluation: The method uses transmitted-light optical microscopy at ×200 (oil of linseed may be used) to examine a representative field of at least 50 particles and to count lamellar (red-translucent) versus non-lamellar (dark) particles. The procedure and apparatus are specified for reproducible classification.
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Agreement items: Certain parameters (pH of aqueous suspension, oil absorption relative to an agreed reference, total CaO) are to be agreed between supplier and purchaser when needed.
Applications
ISO 10601:2007 is targeted at manufacturers, test laboratories, specifiers and coating formulators involved in protective coatings for steel. Benefits and functional outcomes when using MIO pigments meeting the standard:
- Improved barrier formation through overlapping lamellae in paint films
- Reduced ingress of corrosion agents and enhanced corrosion resistance
- Decreased binder degradation from UV exposure and improved film durability
Practical uses include primers and protective topcoats for structural steel, offshore, industrial and heavy-duty protective systems.
Related Standards
The standard cross-references and aligns with other ISO methods and standards cited in the document, including:
- ISO 1248 – iron-oxide pigments specifications and test methods
- ISO 3549 – zinc dust pigments (sieve/refusal test reference used)
- ISO 787-2, -3, -5, -9 – general pigment test methods (volatile matter, water-soluble matter, oil absorption, pH)
- ISO 150 – linseed oil requirements (used for the microscopy preparation)
- ISO 15528 – sampling procedures
For testing, reporting and procurement, laboratories and purchasers should reference ISO 10601:2007 directly and agree any supplemental acceptance criteria (reference pigment, pH, oil absorption, CaO content) before supply.
