Overview
ISO 277:2002 - "Binders for paints and varnishes - Raw tung oil - Requirements and methods of test" specifies requirements and agreed test methods for two types of raw tung oil used as binders in paints and varnishes. It covers Type F (from Aleurites fordii) and Type M (from Aleurites montana) and explicitly excludes tung oils that have wholly or partly solidified by polymerization. The standard defines compositional, physical and performance characteristics, and sets out test procedures (sampling, gelation test, insoluble‑bromide test and analytical determinations).
Key topics and requirements
- Types covered: Type F and Type M raw tung oil ( botanical origins specified ).
- Physical properties:
- Density at 20 °C and 23 °C (specific ranges for Type F and M; change per °C = 0.00068).
- Refractive index at 20 °C and 23 °C (temperature correction given).
- Colour by Gardner scale (max. 8).
- Chemical characteristics:
- Saponification number: 189–195 mg KOH/g.
- Acid number: maximum 5 mg KOH/g (free acid expressed as oleic acid ≤ 2.5%).
- Unsaponifiable matter: max. 1% by mass.
- Iodine number: Type M minimum 205 (calculated from fatty‑acid composition).
- Volatile matter (water): max. 0.5% by mass (Karl Fischer referenced).
- Performance indicators:
- Gelation time (measured by the standard procedure): Type F max 15 min, Type M max 22 min.
- Sediment and turbidity: no insoluble sediment after 24 h; oil must be clear.
- Insoluble‑bromide test: negative (no insoluble bromide).
- Fatty‑acid composition: Typical ranges are provided (e.g., α‑eleostearic acid 64–80%, oleic 4.5–8%, linoleic 6–9%) determined by GC (ISO 5508 / ISO 5509).
- Referenced test methods: Sampling (ISO 15528), density (ISO 2811‑1), refractive index (ISO 5661), Gardner colour (ISO 4630), saponification (ISO 3681), acid values (ISO 2114), GC analysis (ISO 5508/5509), water (ISO 10336).
Applications and who uses it
ISO 277 is intended for:
- Paint and varnish manufacturers specifying tung oil binders for formulation and performance.
- Raw material suppliers and processors for quality control and specification compliance.
- Testing laboratories performing acceptance and batch testing using harmonized methods.
- Procurement, import/export and regulatory bodies that require standardized product criteria.
Practical benefits include ensuring consistent drying/film‑formation behavior, chemical compatibility in formulations, and traceable quality for industrial and restoration coatings.
Related standards
Keywords: ISO 277:2002, raw tung oil, binders for paints and varnishes, test methods, gelation time, fatty‑acid composition, saponification number, density, Gardner colour, quality control.