ISO 6744-3:1999

Overview

ISO 6744-3:1999 - Binders for paints and varnishes - Alkyd resins - Part 3: Determination of unsaponifiable matter content - specifies a laboratory method to measure the unsaponifiable matter in alkyd resins. The procedure is performed after the saponification step described in ISO 6744-2 and is not applicable to modified alkyd resins (see ISO 6744‑1:1999). This standard is intended for quality control and compositional analysis of binders used in paints and varnishes.

Key topics and technical requirements

• Scope and linkage: Always used in conjunction with ISO 6744‑2 (first step: saponification and filtration). References include ISO 6744‑1, ISO 6744‑4, ISO 3696 and sampling guidance (ISO 15528).
• Principle: Dry the filtrate from ISO 6744‑2, extract non‑saponifiable components with an organic solvent, evaporate solvent, dry and weigh the residue. Calculate percentage of unsaponifiables relative to the initial sample mass.
• Extraction methods: Two validated options:
  • Diethyl ether method (with hydroquinone added to ether to inhibit peroxides).
  • Light petroleum (petroleum ether 30/50) method - recommended where ether emulsions are problematic.
• Reagents: Analytical grade solvents (diethyl ether, light petroleum 30/50), ethanol (95 % v/v), acetone, KOH solution (56 g/L), laboratory water (ISO 3696 quality 3).
• Apparatus: Standard lab glassware including 250 mL separatory (decanting) funnels, rotary evaporator or water bath for solvent removal, and drying oven at ~105 °C.
• Operational details:
  • Perform determinations in duplicate.
  • If emulsions form with ether, additives such as ethanol, saturated NaCl or a few drops of dilute mineral acid may be used to break them.
  • Dry residue to constant mass: consecutive weighings must not differ by more than 0.1% (of the lower value); weigh to 1 mg accuracy.
• Calculation: Unsaponifiable content w (%) = (mass of dried residue / mass of test portion) × 100, where the test portion mass is as defined in ISO 6744‑2.

Applications and users

• Who uses it: Paint and varnish manufacturers, raw material suppliers, quality control laboratories, and R&D teams analyzing alkyd binder composition.
• Practical uses:
  • Quality control of alkyd resin batches.
  • Verification of raw material purity and consistency.
  • Supporting product specifications and regulatory documentation.
  • Troubleshooting formulation and performance issues related to non‑saponifiable fractions.

Related standards

• ISO 6744-1:1999 - General test methods for alkyd resins
• ISO 6744-2:1999 - Determination of phthalic anhydride content (first step in this analysis)
• ISO 6744-4:1999 - Determination of fatty acid content
• ISO 3696 - Laboratory water quality
• ISO 15528 - Sampling for paints, varnishes and raw materials

Keywords: ISO 6744-3:1999, alkyd resins, unsaponifiable matter content, binders for paints and varnishes, extraction method, diethyl ether, petroleum ether, laboratory analysis.