Overview
EN ISO 9117-4:2012 - Paints and varnishes - Drying tests - Part 4: Test using a mechanical recorder - specifies a standardized laboratory method to determine the times taken to reach stages of drying of organic coatings using a mechanical drying-time recorder. The test records how a stylus interacts with a wet film (straight-line or circular motion) to quantify set-to-touch, tack-free, hard-dry and through-dry behaviour. It is particularly useful for comparing drying behaviour between coatings of the same generic type and for simulating conditions when painted articles are stacked.
Key Topics and Requirements
- Scope: Measurement of drying stages for organic coatings using a straight-line (Method A) or circular (Method B) mechanical recorder.
- Apparatus:
- Straight-line recorder with multiple rounded styluses (typical stylus weights supplied ~5 g; additional weights allowed by agreement) and adjustable speeds for 6 h, 12 h and 24 h tests.
- Circular recorder with PTFE stylus (~10 mm tip), typical load ~12 g, transparent timing template and motor mounted on a rubber-shod tripod.
- Test panels & substrates: Clean glass panels per ISO 1514; glass strips (~300 × 25 mm) for straight-line, glass plate (~150 × 150 mm) for circular.
- Sampling & preparation: Follow ISO 15528 (sampling) and ISO 1513 (sample preparation). Apply coating and record application time.
- Test conditions: Conduct at least duplicate tests at (23 ± 2) °C and ambient relative humidity unless otherwise agreed (see ISO 3270).
- Procedure:
- Immediately start recorder after coating; lower stylus and mark start point on film.
- After drying, evaluate scribed tracks with magnification and template to determine time for each drying stage.
- Calculate drying time as distance covered divided by stylus speed.
- Reporting: Include coating method, dry-film thickness (determine per ISO 2808), number of tests, environmental conditions and any weights/speeds used.
Applications and Users
- Useful for paint manufacturers, R&D chemists, quality control laboratories and coatings formulators who need to:
- Compare drying kinetics between formulations or raw-material changes.
- Assess gel formation rate, scratch resistance during drying and stackability risk.
- Evaluate coatings with drying characteristics that extend beyond an 8-hour workday.
- Practical for production troubleshooting, specification verification and pre‑market product comparisons where drying behaviour affects handling, packaging or stacking.
Related Standards
Keywords: EN ISO 9117-4:2012, drying tests, mechanical recorder, paints and varnishes, drying time, straight-line recorder, circular recorder, test method, film thickness.
