ISO 14680-1:2000

Overview

ISO 14680-1:2000 specifies a centrifuge method to determine the pigment content of paints and varnishes. The method separates solids from the binder by centrifugation, dries and weighs the residue, and expresses pigment content as a percentage by mass. It is primarily intended for production composition checks and acceptance testing. The method may be less suitable for emulsion paints and for formulations containing dyestuffs, carbon black, very finely divided silicon dioxide or titanium dioxide.

Key Topics

• Principle: dilute a test portion in a suitable solvent, separate solids by centrifugation, wash, dry at (125 ± 2) °C and weigh the residue.
• Apparatus highlights: laboratory centrifuge (relative centrifugal acceleration about 250 000, ≈25 000 g) with balanced swivelling buckets; centrifuge tubes (e.g. 50 ml); polished-ball stirrer; drying oven with forced ventilation; analytical balance (0,001 g); desiccator.
• Test portions (examples):
  • 50 ml tube: test portion 10 ± 0,2 g, solvent ≈ 20 ml
  • 100 ml tube: test portion 15 ± 0,3 g, solvent ≈ 40 ml
• Procedure (summary):
  1. Weigh the clean, dry centrifuge tube (m0).
  2. Add the test portion and solvent; dissolve binder with ball stirrer; rinse residue into tube.
  3. Centrifuge until solids sediment (typically about 20 min); decant supernatant.
  4. Resuspend, dilute to mark and repeat centrifugation 2–4 times as needed.
  5. Dry tube with residue to constant mass at (125 ± 2) °C, cool in desiccator and weigh (m2).
• Calculation:
  • Pigment content (%) = [(m2 − m0) / (m1 − m0)] × 100
    • where m0 = mass of empty tube, m1 = mass of tube + test portion, m2 = mass of tube + dried residue.
• Replicates: perform the test in duplicate. If duplicates differ by more than 2% (relative to the mean), repeat.

Applications

• Quality control during paint and varnish production
• Acceptance checks for incoming or supplied coating materials
• Comparative testing for formulation adjustments

Benefits: provides a practical, repeatable measure of solids that include pigments and extenders; useful for process control and product specification verification.

Related Standards

• ISO 14680-2 - Ashing method for pigment content determination
• ISO 14680-3 - Filtration method for pigment content determination
• ISO 1513 - Examination and preparation of samples for testing
• ISO 15528 - Sampling of paints, varnishes and raw materials

Reporting requirements: the test report shall identify the product, reference ISO 14680-1, list the solvent used, give individual and mean results (to 0,1 % mass), note any deviations from the method and state the test date.

Precision (example at ~30 % pigment): repeatability r = 2 %; reproducibility R = 4 %.