Overview
ISO 6744-4:1999 specifies a laboratory method for the determination of fatty acid content in alkyd resins, part of the ISO 6744 series for binders used in paints and varnishes. This part is intended to be used together with ISO 6744-2 and ISO 6744-3 (which cover preceding analysis steps) and is not applicable to modified alkyd resins or resins containing benzoic acid. The method measures fatty acids remaining after saponification and removal of unsaponifiable matter and expresses the result as a percentage by mass.
Key topics and requirements
- Scope and applicability: Applies to conventional alkyd resins; excludes modified alkyd resins and resins with benzoic acid.
- Analytical principle: Determine fatty acid content after saponification and removal of unsaponifiable matter; extract fatty acids into diethyl ether, evaporate solvent and weigh the residue.
- Sample handling: Sampling should follow ISO 15528 to ensure representative test portions.
- Reagents and apparatus:
- Diethyl ether (peroxide-free, with hydroquinone), acetone, hydrochloric acid (~73 g/L), silver nitrate (~10 g/L).
- Separating funnel (250 ml), distillation/rotary evaporator or water bath, vacuum drying oven (~60 °C).
- Procedure essentials:
- Work in duplicate.
- Acidify aqueous solution, extract three times with diethyl ether.
- Wash combined ether extracts until no chloride detected (silver nitrate test).
- Evaporate solvent (rotary evaporator or water bath with safety precautions), remove residual water with acetone if needed.
- Dry residue in vacuum oven at ~60 °C to constant mass (consecutive weighings within 0.1%).
- Result expression: Fatty acid content (%) = (mass of residue after evaporation / mass of test portion) × 100.
- Quality and reporting: Report reference to ISO 6744-4, product identification, result, deviations, and test date.
Applications and users
ISO 6744-4 is used for quality control, specification verification and R&D where accurate fatty acid quantification in alkyd resins is required. Typical users:
- Paint and varnish manufacturers (formulation and QC labs)
- Raw material suppliers and resin producers
- Independent testing laboratories and accreditation bodies
- R&D chemists evaluating alkyd resin composition and consistency
Practical benefits include reproducible fatty acid measurement for batch control, ingredient traceability, and compliance with contractual or regulatory specifications.
Related standards
- ISO 6744-1:1999 - General methods of test for alkyd resins
- ISO 6744-2:1999 - Determination of phthalic anhydride content (preceding steps)
- ISO 6744-3:1999 - Determination of unsaponifiable matter content (preceding steps)
- ISO 3696 - Water for analytical laboratory use
- ISO 15528 - Sampling of paints, varnishes and raw materials
Keywords: ISO 6744-4, fatty acid content, alkyd resins, binders for paints and varnishes, test method, saponification, unsaponifiable matter, paint industry quality control.
Open preview (PDF)Binders for paints and varnishes — Alkyd resins — Part 4: Determination of fatty acid content
